tag:blogger.com,1999:blog-54622424724244912652024-02-08T01:53:58.193+07:00all about welding inspector worldAll information about welding inspector world, code and standard used, daily inspection, documenting and reporting belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.comBlogger16125tag:blogger.com,1999:blog-5462242472424491265.post-9120928309396227522016-06-19T06:18:00.000+07:002016-06-19T06:18:42.000+07:00Miscellaneous imperfections according to BS EN ISO 6520-1 <h3>
<span style="font-weight: normal;">Types of </span><span style="font-weight: normal;">m</span>iscellaneous imperfections:</h3>
<div>
<ol>
<b>
<li>Stray arc (arc strike)</li>
</b><br />
<img alt="arc strike" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEhN4XTvdPndJSRkuU_Yp5i32gZIxcQyoY70f7umSkhw4S5rTNkSQJakz9MmO1e0RgGugj8DEdqBl7tsZv9cwjR7N0oBFP3jQHsCRVRzGTxnsI7V2hJvSZrLwcZBhoo4-LnKoTRsQDWQc/s320/ArcStrike+image.jpg" title="stray arc image" /><br /><br />Local damage to the surface of the parent metal adjacent to the weld, resulting from arcing or striking the arc outside the weld groove. This results in random areas of fused metal where the electrode, holder or current return clamp have accidentally touched the work.
<br /><br />
<b>Causes</b>:
<ul>
<li>Poor access to the work</li>
Prevention: Improve access (modify assembly sequence)
<li>Missing insulation on electrode holder or torch</li>
Prevention: Institute a regular inspection scheme for electrode holders and torches
<li>Failure to provide an insulated resting place for the electrode holder or torch when not in use</li>
Prevention: Provide an insulated resting place
<li>Loose current return clamp</li>
Prevention: Regularly maintain current return clamps
<li>Adjusting wire feed (MAG welding) without isolating welding current</li>
Prevention: Retrain welder
</ul>
<br />
An arc strike can produce a hard HAZ which may contain cracks, possibly
leading to serious cracking in service. It is better to remove an arc strike by
grinding than weld repair.<br /><br />
<b>
<li>Spatter</li>
<br />
</b><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6_gVDV6S3LKjgQ3n92YTXZQSvjHauuhaIuWV0FCRN0naPb8QzI5jRc8jTCE4NwabOTsekSyy1lpMObzFESYujWoAE_5Kfh43Np5RFOHkbtBVTqVYhye4BsLw8geF7vtVFgfabBAdsQ_0/s320/spatter+image.jpg" /><br /><br />Globules of weld or filler metal expelled during welding adhering to the
surface of parent metal or solidified weld metal.
<br /><br />
<b>Causes</b>:
<ul>
<li>High arc current</li>
Prevention: Reduce arc current
<li>Long arc length</li>
Prevention: Reduce arc length
<li>Magnetic arc blow</li>
Prevention: Reduce arc length or switch to AC power
<li>Incorrect settings for GMAW process</li>
Prevention: Modify electrical settings (but be careful to maintain full fusion!)
<li>Damp electrodes</li>
Prevention: Use dry electrodes
<li>Wrong selection of shielding gas (100% CO2)</li>
Prevention: Increase argon content if possible, however if too high may lead to lack of penetration
</ul>
<br />
Spatter is a cosmetic imperfection and does not affect the integrity of the weld. However as it is usually caused by an excessive welding current, it is a sign that the welding conditions are not ideal so there are usually other associated problems within the structure, ie high heat input. Some spatter is always produced by open arc consumable electrode welding processes. Anti-spatter compounds can be used on the parent metal to reduce sticking and the spatter can then be scraped off.<br /><br />
<b>
<li>Torn surface</li>
</b>
<br /><img alt="temporary welded attachment" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgX828ENCoJzct8gshU9-jH1ns4EDgrSFhvD7uNuBRDPjSOvUx6TJIIRT72zMtIMWJFVlYqaPNRwvFQzXsXajkJEEC46chIZVm7PfU4cH0_3uuz6Qf0sqjn_odsx47OfyYtZaxeq-N1ZT0/s320/torn+surface+image.jpg" title="torn surface" /><br /><br />
Surface damage due to the removal by fracture of temporary welded
attachments. The area should be ground off, subjected to a dye penetrant or
magnetic particle examination then restored to its original shape by welding
using a qualified procedure. Some applications do not allow the presence of
any overlay weld on the surface of the parent material.<br /><br />
<b>
<li>Additional imperfections</li>
</b><br />
<ul>
<li>Grinding mark</li>
Local damage due to grinding.
<li>Chipping mark</li>
Local damage due to the use of a chisel or other tools.
<li>Underflushing</li>
Lack of thickness of the workpiece due to excessive grinding.
<li>Misalignment of opposite runs</li>
Difference between the centrelines of two runs made from opposite sides of the joint.
<li>Temper colour (visible oxide film)</li>
Lightly oxidised surface in the weld zone, usually occurs in stainless steels.
</ul>
</ol>
</div>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com2tag:blogger.com,1999:blog-5462242472424491265.post-11373617873579194172016-06-17T04:11:00.000+07:002016-06-17T04:11:36.795+07:00Imperfect Shape and Dimensions according to BS EN ISO 6520-1 <h3>
Types of<b> Imperfect Shapes and Dimensions</b>:</h3>
<ol><b>
<li>Undercut</li>
<br />
</b><img alt="undercut image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3edyXFD39wYwvGW46EGzbaYmLUypHHftvcTa3cMfIAvT5QvYLDUNq-PDV0UFgPqRCjbT0waXlRCIFgNFlmZotkBRM4meBkAPyAVJW7GwDA6nrh5LhGHwh6hQmN77aF6I6y8FYFGwZvok/s320/undercut+image.jpg" title="undercut image" /><br /><br />
An irregular groove at the toe of a run in the parent metal or previously deposited weld metal due to welding. Characterised by its depth, length and sharpness.<br /><b>Causes</b>:
<ol>
<ul>
<li>Melting of top edge due to high welding current (especially at the free edge) or high travel speed</li>
Prevention: Reduce power input, especially approaching a free edge where overheating can occur
<li>Attempting a fillet weld in horizontal-vertical (PB) position with leg length >9mm</li>
Prevention: Weld in the flat position or use multi-run techniques
<li>Excessive/incorrect weaving</li>
Prevention: Reduce weaving width or switch to multiruns
<li>Incorrect electrode angle</li>
Prevention: Direct arc towards thicker member
<li>Incorrect shielding gas selection (MAG)</li>
Prevention: Ensure correct gas mixture for material type and thickness (MAG)
</ul>
</ol>
Care must be taken during weld repairs of undercut to control the heat input. If the bead of a repair weld is too small, the cooling rate following welding will be excessive and the parent metal may have an increased hardness and the weld susceptible to hydrogen cracking.<br /><br />
<b>
<li>Excess weld metal</li>
</b><br /><img alt="Excess weld metal" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSFExNRZZbHzU1PZepvYyTsbXTRcQBboX3JgqCIt2kK8QgYEFSrBe8AEEj8EOYyHcR-oJioZ6UaQ48ufaThU7QwbtpdxuCGYMOjp2uJeA2LTDbMAkR9Tt4w3npVnuuSUiQfKlcPl7mvkM/s320/convex+weld.jpg" title="Excess weld metal image" /><br /><br />
Excess weld metal is the extra metal that produces excessive convexity in fillet welds and a weld thickness greater than the parent metal plate in butt welds. It is regarded as an imperfection only when the height of the excess weld metal is greater than a specified limit.<br /><b>Causes</b>:
<ol>
<ul>
<li>Excess arc energy (MAG, SAW)</li>
Prevention: Reduction of heat input
<li>Shallow edge preparation</li>
Prevention: Deepen edge preparation
<li>Faulty electrode manipulation or build-up sequence</li>
Prevention: Improve welder skill
<li>Incorrect electrode size</li>
Prevention: Reduce electrode size
<li>Travel speed too slow</li>
Prevention: Ensure correct travel speed is used
<li>Incorrect electrode angle</li>
Prevention: Ensure correct electrode angle is used
<li>Wrong polarity used (electrode polarity DC-ve (MMA, SAW)</li>
Prevention: Ensure correct polarity ie DC+ve Note DC-ve must be used for TIG
</ul>
</ol>
The term reinforcement used to designate this feature of the weld is misleading since the excess metal does not normally produce a stronger weld in a butt joint in ordinary steel. This imperfection can become a problem, as the angle of the weld toe can be sharp leading to an increased stress concentration at the toes of the weld and fatigue cracking.<br /><br />
<b>
<li>Excess penetration</li>
</b><br /><img alt="Excess penetration" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDz0eZ0_kgQod8EsymsVgcCRbCrKsK06i4K5ib3yxE_qNKjrwkr4O2Dtpxs2JHD6m1LJn3znRjmHsN9txRsiOyeAy29U21EznmWO_AJX7fcUVl1C3fK7duXcWGU-JDv_KYiCjb97bOTWU/s320/excessive+penetration+image.png" title="Excess penetration image" /><br /><br />
Projection of the root penetration bead beyond a specified limit, local or continuous.<br /><b>Causes</b>:
<ol>
<ul>
<li>Weld heat input too high</li>
Prevention: Reduce arc voltage and/or welding current;increase welding speed
<li>Incorrect weld preparation ie excessive root gap, thin edge preparation, lack of backing</li>
Prevention: Improve workpiece preparation
<li>Use of electrode unsuited to welding position</li>
Prevention: Use correct electrode for position
<li>Lack of welder skill</li>
Prevention: Retrain welder
</ul>
</ol>
The maintenance of a penetration bead of uniform dimensions requires a great deal of skill, particularly in pipe butt welding. This can be made more difficult if there is restricted access to the weld or a narrow preparation. Permanent or temporary backing bars can assist in the control of penetration.<br /><br />
<b>
<li>Overlap</li>
</b><br /><img alt="overlap" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtNKRdwuncKHn1-LV3j7IbNshTiM41xuJZ-EQkXYu7m6OzbsA6NtgyxS4WHfMKxBrgEBdn_ujFMX0zp8WjoNTkKHyWfiliFEvM7xCAiIidGnNtvV_Z13I-_dnA0WBkhAYR2WbfSKlkWN8/s320/overlap+image.jpg" title="overlap weld image" /><br /><br />Imperfection at the toe of a weld caused by metal flowing on to the surface of the parent metal without fusing to it.<br /><b>Causes</b>:
<ol>
<ul>
<li>Poor electrode manipulation (MMA)</li>
Prevention: Retrain welder
<li>High heat input/low travel speed causing surface flow of fillet welds</li>
Prevention: Reduce heat input or limit leg size to 9mm maximum for single pass fillets
<li>Incorrect positioning of weld</li>
Prevention: Change to flat position
<li>Wrong electrode coating type resulting in too high a fluidity</li>
Prevention: Change electrode coating type to a more suitable fast freezing type which is less fluid
</ul>
</ol>
For a fillet weld overlap is often associated with undercut, as if the weld pool is too fluid the top of the weld will flow away to produce undercut at the top and overlap at the base. If the volume of the weld pool is too large in a fillet weld in horizontal-vertical (PB) position, weld metal will collapse due to gravity, producing both defects (undercut at the top and overlap at the base), this defect is called sagging.<br /><br />
<b>
<li>Linear misalignment</li>
</b><br /><img alt="linear misalignment image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhebA6ysuuzt6nIiwMt_Ns89WLmmAhWcNuJAYgLA_YM-aKvswh-27fm1i59cIiBBhvtTS7BdswJoWqWOQn29qCX44pCypsSx3dDhjxLDs1PvBDp7Arc9khSoqtrrsoAwptTogsMOWoyltg/s320/misalignment.jpg" title="linear misalignment image" /><br /><br />Misalignment between two welded pieces such that while their surface planes are parallel, they are not in the required same plane.<br /><b>Causes</b>:
<ol>
<ul>
<li>Inaccuracies in assembly procedures or distortion from other welds</li>
Prevention: Adequate checking of alignment prior to welding coupled with the use of clamps and wedges
<li>Excessive out of flatness in hot rolled plates or sections</li>
Prevention: Check accuracy of rolled section prior to welding
</ul>
</ol>
Misalignment is not a weld imperfection but a structural preparation problem. Even a small amount of misalignment can drastically increase the local shear stress at a joint and induce bending stress.<br /><br />
<b>
<li>Angular distortion</li>
</b><br /><img alt="angular distortion image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjo75hqzjhKF2jQdfEU7uWI2PGdUYyAsxjbDMl6N3L522KZtP9REm7H8VAVgE2LEbm5yECfyfTaiQmb5t2soPlJMIap28GVJSAKPLeXdkh4zGvc4kvy-eO-EXUATJyaRgU63_-kyY8c5-I/s320/angular+distortion.jpg" title="angular distortion image" /><br /><br />Misalignment between two welded pieces such that their surface planes are
not parallel or at the intended angle.
Causes and prevention are the same as for linear misalignment.<br /><br />
<b>
<li>Incompletely filled groove</li>
</b><br /><img alt="incompletely filled groove image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjm-PWZeG9bKKQNUSd2Hy9DpHVfiRK_qZQQMCVMwzrEp1h-GI2D3WkpHCkq_FtYMtIno6CZDxxtQJIDMfPLXhEmAxGzST6LXV_hO11ifSPo-0dWvTwXuVzWVXOewi2Azqlr3olLbn3vIDQ/s320/Under+fill.jpg" title="incompletely filled groove image" /><br /><br />Continuous or intermittent channel in the weld surface due to insufficient
deposition of weld filler metal.<br /><b>Causes</b>:
<ol>
<ul>
<li>Insufficient weld metal</li>
Prevention: Increase the number of weld runs
<li>Irregular weld bead surface</li>
Prevention: Retrain welder
</ul>
</ol>
This imperfection differs from undercut, as it reduces the load-bearing
capacity of a weld, whereas undercut produces a sharp stress-raising notch
at the edge of a weld.<br /><br />
<b>
<li>Irregular width</li>
</b><br /><img alt="irregular width image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg16k24ZwlF6c8SY1eyhyphenhyphenD1SRlZZlE7VtU5fUy1CrpaB4qWOx6eqsU4n8LPsAwAB9aHLK4UdwjLF75b2oOw4nfdjjMiWDMtEWnfaeH2hk0l-Fw6QFhSRwk4xMBgjGxpmiHc_Q3T69VOAU8/s320/irregular+width.jpg" title="irregular width image" /><br /><br />Excessive variation in width of the weld.<br /><b>Causes</b>:
<ol>
<ul>
<li>Severe arc blow</li>
Prevention: Switch from DC to AC, keep arc length as short as possible
<li>Irregular weld bead surface</li>
Prevention: Retrain welder
</ul>
</ol>
Although this imperfection may not affect the integrity of the completed weld, it can affect the width of HAZ and reduce the load-carrying capacity of the joint (in fine-grained structural steels) or impair corrosion resistance (in duplex stainless steels).<br /><br />
<b>
<li>Root concavity</li>
</b><br /><img alt="root concavity image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQgXWfbL1FMkhyphenhyphene7lRLMRGI1w1Cpe99WkAu1vXA8tdHiQJvK24ArOOg9ayqOocuE0X8BNw73zrgDOrZnaR8VfcRiN8a3vW41JqI73suGGBuDB3yJoYMkD4VSFe01UzvyPgn9k3_ig7vA4/s320/concave++root+image.jpg" title="root concavity image" /><br /><br />A shallow groove that occurs due to shrinkage at the root of a butt weld.<br /><b>Causes</b>:
<ol>
<ul>
<li>Insufficient arc power to produce positive bead</li>
Prevention: Raise arc energy
<li>Incorrect preparation/fit-up</li>
Prevention: Work to WPS
<li>Excessive backing gas pressure (TIG)</li>
Prevention: Reduce gas pressure
<li>Lack of welder skill</li>
Prevention: Retrain welder
<li>Slag flooding in backing bar groove</li>
Prevention: Tilt work to prevent slag flooding
</ul>
</ol>
A backing strip can be used to control the extent of the root bead.<br /><br />
<b>
<li>Burn-through</li>
</b><br /><img alt="burn through image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHS-m7Ml62SfLaeAeu_LmAv2-qSbkxjTZ2_6BgdtV_BcrxURE_QJOoChQ6JbArmUb4b0I9id2YEWoGVPJKYPOfc7wugLqjEWrkOKo1h2KYBhioSBv1_l5O63iNgpx8R7-dWzl67IrZnRQ/s320/burn+through+image.jpg" title="burn through image" /><br /><br />A collapse of the weld pool resulting in a hole in the weld.<br /><b>Causes</b>:
<ol>
<ul>
<li>Insufficient travel speed</li>
Prevention: Increase the travel speed
<li>Excessive welding current</li>
Prevention: Reduce welding current
<li>Lack of welder skill</li>
Prevention: Retrain welder
<li>Excessive grinding of root face</li>
Prevention: More care taken, retrain welder
<li>Excessive root gap</li>
Prevention: Ensure correct fit-up
</ul>
</ol>
This is a gross imperfection which occurs due to lack of welder skill but can
be repaired by bridging the gap formed into the joint, but requires a great
deal of attention.<br /><br />
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-42375560607620957082016-06-15T14:22:00.004+07:002016-06-15T14:22:56.650+07:00Definition and Types of Lack of Fusion and Penetration according to BS EN ISO 6520-1<b>Lack of fusion</b> is lack of union between the weld metal and the parent metal or between the successive layers of weld metal.<br />
Types of lack of fusion:<br />
<ol><b>
<li>Lack of sidewall fusion</li>
</b>
<br />
<img alt="LOF" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcxJWTrWOM3hUp2ZmpfgeUKRq5zyoK-AoNUrRLjsqkz5bjX3TGOpcjyLyYrMUerSh8VJyP4lb4HKvgvt8-nq1ipDYpBAgli-Q_tVr-DusQr8r5MotTil07w9fSE-o-R6ory8IBv5DqCJg/s320/lack+of+sidewall+fusion.jpg" title="Lack of sidewall fusion image" /><br /><br />
Lack of union between the weld and parent metal at one or both sides of the
weld.<br /><br />
<b>Causes</b>:
<ul>
<li>Low heat input to weld</li>
Prevention: Increase arc voltage and/or welding current; decrease travel speed
<li>Molten metal flooding ahead of arc</li>
Prevention: Improve electrode angleg alend work position; increase travel speed
<li>Oxide or scale on weld preparation</li>
Prevention: Improve edge preparation procedure
<li>Excessive inductance in MAG dip transfer welding</li>
Prevention: Reduce inductance, even if this increases spatter</ul>
<br />
During welding sufficient heat must be available at the edge of the weld pool to produce fusion with the parent metal.<br /><br />
<b>
<li>Lack of inter-run fusion</li>
</b><br />
<img alt="" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxTgz68pIjCzIEnx3pwr6DFw1zMdzCunEqXo0aNxO19PlF0Y2GbU7XnwYlDjO8-1BSpuXSEo5wLdAaA1DXx4euerPydNmzNFIbdVaZwPjnWo7lamW2HcWvS6Y4Sbbi456ASWAOhX_Lc5Y/s320/lack+of+inter+run+fusion.jpg" title="lack of inter run fusion image" /><br /><br />
Lack of union along the fusion line between the weld beads.
<br /><br />
<b>Causes</b>:
<ul>
<li>Low arc current resulting in low fluidity of weld pool</li>
Prevention: Increase current
<li>Too high a travel speed</li>
Prevention: Reduce travel speed
<li>Inaccurate bead placement</li>
Prevention: Retrain welder
</ul>
<br />
Lack of inter-run fusion produces crevices between the weld beads and causes local entrapment of slag.<br /><br />
<b>
<li>Lack of root fusion</li>
</b><br />
<img alt="" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwu_lCaKnBFqvDjAtbcT7ZsKzc1Y0zXCMwuVI5l_iodgdcazmusMvaiX7EpPeB9Mn09Egr0Zr7xn8OFsZNEu6jlvdSsbvTiFUFu1w2pdtJQIXBURX9bt9ztUPuEm75MAirmISFw4a1cPc/s320/lack+of+root+fusion.jpg" title="lack of root fusion" /><br /><br />
Lack of fusion between the weld and parent metal at the root of a weld.
<br /><br />
<b>Causes</b>:
<ul>
<li>Low heat input</li>
Prevention: Increase welding current and/or arc voltage; decrease travel speed
<li>Excessive inductance in MAG dip transfer welding</li>
Prevention: Use correct induction setting for the parent metal thickness
<li>MMA electrode too large (low current density)</li>
Prevention: Reduce electrode size
<li>Use of vertical-down welding</li>
Prevention: Switch to vertical-up procedure
<li>Large root face</li>
Prevention: Reduce root face
<li>Small root gap</li>
Prevention: Ensure correct root opening
<li>Incorrect angle or electrode manipulation</li>
Prevention: Use correct electrode angle; ensure welder is fully qualified and competent
<li>Excessive misalignment at root</li>
Prevention: Ensure correct alignment
</ul>
</ol>
<br />
Types of <b>Lack of Penetration</b>:<br />
<ol>
<b>
<li>Incomplete penetration</li>
</b><br />
<img alt="" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2UIjTjqqg8SzHSj5e6nXhLI2gRQBNRitH2LZ284INx80sdvPDRhcy6qUp6cr5UDomf01eJUw0LXMn8D530DNa8r1HOS_pYQA6ldrcUsb8KtdkykbJkfnr7QrLmFLEMMJQ-hvzq0xI2Sk/s320/incomplete+penetration.jpg" title="incomplete penetration image" /><br /><br />
The difference between actual and nominal penetration.<br /><br />
<b>Causes</b>:
<ul>
<li>Excessively thick root face, insufficient root gap or failure to cut back to sound metal when back gouging</li>
Prevention: Improve back gouging technique and ensure the edge preparation is as per approved WPS
<li>Low heat input</li>
Prevention: Increase welding current and/or arc voltage; decrease travel speed
<li>Excessive inductance in MAG dip transfer welding, pool flooding ahead of arc</li>
Prevention: Improve electrical settings and possibly switch to spray arc transfer
<li>MMA electrode too large (low current density)</li>
Prevention: Reduce electrode size
<li>Use of vertical-down welding</li>
Prevention: Switch to vertical-up procedure</ul>
<br />
If the weld joint is not of a critical nature, ie the required strength is low and the area is not prone to fatigue cracking, it is possible to produce a partial
penetration weld. In this case incomplete root penetration is considered part of this structure and not an imperfection This would normally be determined by the design or code requirement.<br /><br />
<b>
<li>Incomplete root penetration</li>
</b><br />
<img alt="" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhprYam3HL4WYmEewfL4pZZz29lQ8wzbwEsvTohseHdqIm0Vefyy7pW8Fg5uPRlARE2ahl_Sfr8ZSIVAOSFStxht76a2D6xJM8Pj_1d5gvtj7d7kEX_0TUrJ348RL52loI4zOetVrmtgKg/s320/incomplete+root+penetration.jpg" title="incomplete root penetration image" /><br /><br />
Both fusion faces of the root are not melted. When examined from the root
side, you can clearly see both of the root edges unmelted.<br /><br />
Causes and prevention
Same as for lack of root fusion.
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com1tag:blogger.com,1999:blog-5462242472424491265.post-91094032246254542372016-06-14T10:01:00.003+07:002016-06-14T10:01:52.909+07:00ASME BPVC Certification Symbol<div style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;">
<img alt="asme stamp" border="0" height="121" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJgA84QZF4sheVYEmOufiYbJ4B2yJBkD3mVvvvCGrWKoCfpKJoSMPOV1kH36ld7Pi_n6DN-crwFZLRXL3X0ym7q0uRHSUCHgL44w9WMMIKpO3b_DNBXJEXm4N81KBY5FRzckfNtoGUCg4/s200/asme+logo.png" title="asme logo" width="200" /></div>
Certification of a manufacturer's or assembler's quality control system in accordance with <a href="https://www.asme.org/shop/certification-and-accreditation/boiler-and-pressure-vessel-certification">ASME</a> Boiler and Pressure Vessel Code (BPVC) Sections I, IV, VIII, X, and/or XII.<br />
<br />
<b>Power Boilers </b><br />
<b>Section I</b><br />
S - Power Boilers<br />
<ul>
<li>A - Assembly of Power Boilers </li>
<li>E - Electric Boilers <div class="separator" style="clear: both; text-align: center;">
<img alt="" border="0" height="208" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCokB9BeLCfquZc99EpGPGblcUErwyNOLPuMU-ZowYn8YC4Xo58cCacsKWRpoO_MhJco774ekz1ENcwGJ-mzCnd9MTqMzg8O0xA5iQdAvrLMn4PXIlPqbhF13mEot4_PQU1iRoESzJdig/s320/new+asme+stamp.jpg" title="new asme stamp" width="320" /></div>
</li>
<li>M - Miniature Boiler </li>
<li>PP - Pressure Piping </li>
<li>V - Boiler Pressure Relief Valves </li>
<li>PRT - Parts
Fabrication</li>
</ul>
<b><br /></b>
<b>Heating Boilers </b><br />
<b>Section IV</b><br />
<ul>
<li>H - Heating Boilers/Cast Iron Sectional Heating Boiler </li>
<li>HLW - Lined Potable Water Heaters </li>
<li>HV - Heating Boiler Safety Valves </li>
<li>PRT - Parts
Fabrication</li>
</ul>
<b><br /></b>
<b>Pressure Vessels </b><br />
<b>Section VIII Division 1</b><br />
<ul>
<li>U - Pressure Vessels </li>
<li>UM - Miniature Pressure Vessels </li>
<li>UV - Pressure Vessel Pressure Relief Valves </li>
<li>UD - Pressure Vessel Pressure Relief Devices</li>
</ul>
<br />
<b>Pressure Vessels </b><br />
<b>Section VIII Division 2</b><br />
<ul>
<li>U2 - Pressure Vessels (Alternative Rules for Pressure Vessels)</li>
</ul>
<b><br /></b>
<b>Pressure Vessels </b><br />
<b>Section VIII Division 3</b><br />
<ul>
<li>U3 - High Pressure Vessels </li>
<li>UV3 - High Pressure Vessel Pressure Relief Valves </li>
<li>UD3 - High
Pressure Vessel
Pressure Relief
Devices</li>
</ul>
<br />
<b>Reinforced Plastic Vessels </b><br />
<b>Section X</b><br />
<ul>
<li>RP - Fiber-Reinforced Plastic Vessels</li>
</ul>
<br />
<b>Transports Tank </b><br />
<b>Section XII</b><br />
<br />
<ul>
<li>T - Transport Tanks </li>
<li>TV - Transport Tanks Pressure Relief Valves </li>
<li>TD - Transport Tanks Pressure Relief Devices </li>
<li>PRT - Parts
Fabrication</li>
</ul>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-19641553510776019212016-06-13T08:46:00.000+07:002016-06-13T08:46:02.265+07:00ASME Single Certification Mark (New Stamp)<div style="clear: left; float: left; margin-bottom: 1em; margin-right: 2em;">
<img alt="new asme stamp" border="0" height="121" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEge0fKwlKQIQ5fr6RjSeJ-7yoVefgDBiyyOUgFLKURL2ZbJcfz5jAzwu5hCSg5Gsj0Y340ijUz0kAxhUyjhQneS0Fw4JGEDy3Ap1lnXDPZKF7WNU9p0MQE6kA3l42lCD17YETxxub1v9mI/s200/asme+logo.png" title="asme logo" width="200" /></div>
<b>ASME</b>'s product certification programs have grown dramatically. Starting with just two countries in the years prior to 1972, there are now 74 countries in which companies have been certified. ASME is proud that the value of these certification programs has been so widely acknowledged, and that ASME is playing this increasingly vital role in fostering product safety and international commerce.
The growth of these programs has presented many new opportunities, but also some challenges, especially regarding how to maintain the trademark registrations of ASME's 28 separate Certification Marks across the more than 100 nations in which these marks are currently used on products.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<img alt="" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzZlH6zJP642ktbU01sluRN5MBhC83-2gw8sufv3flrXMT4i3gHAbfVAE-yNtl01CNwIYQMNBX8VNw1-IQMsWqqgBbErUzPGnMwI9rH-GdtrQSLHNWIkfw0fWX9wH2zE_7aptfM2obJfU/s1600/asme+old+stamp.jpg" title="old asme stamp" /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
In order to streamline our multiple marking processes and more effectively manage our numerous global relationships, ASME is pleased to announce the introduction of a new single Certification Mark.
Instead of 28 separate Certification Marks, there will now be this single comprehensive mark. To maintain a link to the current marks, the new mark will be used in conjunction with a "Certification Designator" to indicate the applicability of the certification.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<img alt="" border="0" height="208" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZK3r5U_Jui6GcqzIUeqIm4hfYWAl30XvWDpTrUR3tnAq4uGuGEzi_uJ1kyuEU0O0dvBDrSBTCat3nmJrPvKgPj1dxIoHxUpfFolW-GFvt_FHlQAnww2fqnVO5UAPBD01yj_mrN5K6fVo/s320/new+asme+stamp.jpg" title="new asme stamp" width="320" /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
The image shows an example of how the new mark would be used on a nameplate (in this case for a vessel constructed to Section VIII, Division 2).<br />
<br />
The old Code Symbol Stamps for ASME BPVC Sections I, IV, VIII, X, and XII (U, S, PP, etc.) were discontinued on January 31, 2013. The N-type Code Symbol Stamps (N, NA, NPT, etc.) may be used until December 31, 2015.
source: <a href="https://www.asme.org/shop/certification-accreditation/frequently-asked-questions">asme.org</a>belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com2tag:blogger.com,1999:blog-5462242472424491265.post-56138380960941666252016-06-12T14:30:00.001+07:002016-06-12T14:30:41.067+07:00Definition and Types of Solid Inclusion according to BS EN ISO 6520-1<div style="clear: left; float: left; margin-bottom: 1em; margin-right: 2em;">
<img alt="slag inclusion" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfM23qAPZbODKQscV2CSRDEFdN4HHZbAMkSqGKbdyUgZoCwHpo2D8ZnWj2COhhEnAyZKdLZv6ME2_WdpHKguoZr9lXrsH1eQ6s_X6aDlnBm9y59QWHkQgnIdHDRkU7lUZqGeEnwIKcHaM/s320/slag+inclusion.jpg" title="solid inclusion image" /></div>
<b>Solid inclusions</b> is solid foreign substances trapped in the weld metal.<br />
Types of solid inclusions:<br />
<ol><b>
<li>Slag inclusions</li>
</b><br />
Slag trapped during welding which is an irregular shape so differs in appearance from a gas pore.
<ol><b>Causes:</b>
<li>Incomplete slag removal from underlying surface of multi-pass weld</li>
Prevention: Improve inter-run slag removal
<li>Slag flooding ahead of arc</li>
Prevention: Position work to gain control of slag
Welder needs to correct electrode angle
<li>Entrapment of slag in work surface</li>
Prevention: Dress/make work surface smooth
</ol>
A fine dispersion of inclusions may be present within the weld metal, particularly if the MMA process is used. These only become a problem when large or sharp-edged inclusions are produced.<br /><br />
<b>
<li>Flux inclusions</li>
</b>
Flux trapped during welding which is an irregular shape so differs in
appearance from a gas pore. Appear only in flux associated welding
processes (ie MMA, SAW and FCAW).
<ol><b>Causes:</b>
<li>Unfused flux due to damaged coating</li>
Prevention: Use electrodes in good condition
<li>Flux fails to melt and becomes trapped in the weld (SAW or FCAW)</li>
Prevention: Change the flux/wire. Adjust welding parameters ie current, voltage etc to produce satisfactory welding conditions
</ol>
<b>
<li>Oxide inclusions</li>
</b>
Oxides trapped during welding which is an irregular shape so differs in appearance from a gas pore.<br />
<b> Causes:</b><br />
Heavy millscale/rust on work surface<br />
Prevention: Grind surface prior to welding
<br />
A special type of oxide inclusion is puckering, which occurs especially in the case of aluminium alloys. Gross oxide film enfoldment can occur due to a combination of unsatisfactory protection from atmospheric contamination and turbulence in the weld pool.
<br /><br />
<b>
<li>Metallic inclusions (Tungsten, Copper, other metal)</li>
</b>
Particles of tungsten can become embedded during TIG welding appears as a light area on radiographs as tungsten is denser than the surrounding metal and absorbs larger amounts of X-/gamma radiation.
<ol><b>Causes:</b>
<li>Contact of electrode tip with weld pool</li>
Prevention: Keep tungsten out of weld pool; use HF start
<li>Contact of filler metal with hot tip of electrode</li>
Prevention: Avoid contact between electrode and filler metal
<li>Contamination of the electrode tip by spatter from the weld pool</li>
Prevention: Reduce welding current; adjust shielding gas flow rate
<li>Exceeding the current limit for a given electrode size or type</li>
Prevention: Reduce welding current; replace electrode with a larger diameter one
<li>Extension of electrode beyond the normal distance from the collet, resulting in overheating of the electrode</li>
Prevention: Reduce electrode extension and/or welding current
<li>Inadequate tightening of the collet</li>
Prevention: Tighten the collet
<li>Inadequate shielding gas flow rate or excessive draughts resulting in oxidation of the electrode tip</li>
Prevention: Adjust the shielding gas flow rate; protect the weld area; ensure that the post gas flow after stopping the arc continues for at least five seconds
<li>Splits or cracks in the electrode</li>
Prevention: Change the electrode, ensure the correct size tungsten is selected for the given welding current used
<li>Inadequate shielding gas (eg use of argon-oxygen or argon-carbon dioxide mixtures that are used for MAG welding)</li>
Prevention: Change to correct gas composition
</ol>
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com1tag:blogger.com,1999:blog-5462242472424491265.post-63228328888726016202016-06-09T20:12:00.000+07:002016-06-09T20:12:44.299+07:00Definition and Types of Cavities according to BS EN ISO 6520-1<b>Cavities</b>, is imperfection formed by entrapped gas, and also caused by shrinkage during solidification. Types of cavities: <br />
<ol>
<b>
<li>Gas Pore </li>
</b><br />
<img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-HP8n6zNM_MO-BjQx9L45pVFwhoh-wsX7iVaSuOLkQwhck7bVwP2z9zcWSEZauClosxZaElrdIyXE727erztdTOLaNj6YZj-AMf7Iz6ld7UDxn0K_iAUpT_HchnF2Mkt7k6AEtviTGPY/s320/Gas+Pore.png" /> <br /> Gas pore: A gas cavity of essentially spherical shape trapped within the weld metal. <br /><br />Gas cavities can be present in various forms:
<ul>
<li>Isolated porosity </li>
<li>Uniformly distributed porosity </li>
<li>Clustered (localised) porosity </li>
<li>Linear porosity </li>
<li>Elongated cavity</li>
<li>Worm hole </li>
<li>Surface pore </li>
</ul>
<br /><b>Causes</b>: <br />
<ol>
<li>Damp fluxes/corroded electrode MMA</li>
Prevention: Use dry electrodes in good condition
<li>Grease/hydrocarbon/water contamination of prepared surface</li>
Prevention: Clean prepared surface <br />
<li>Air entrapment in gas shield (MIG/MAG, TIG)</li>
Prevention: Check hose connections <br />
<li>Incorrect/insufficient deoxidant in electrode, filler or parent metal </li>
Prevention: Use electrode with sufficient deoxidation activity
<li>Too great an arc voltage or length </li>
Prevention: Reduce voltage and arc length <br />
<li>Gas evolution from priming paints/surface treatment </li>
Prevention: Identify risk of reaction before surface treatment is applied <br />
<li>Too high a shielding gas flow rate results in turbulence (MIG/MAG, TIG) </li>
Prevention: Optimise gas flow rate </ol>
<ol><br /></ol>
<b>
<li>Worm Holes</li>
</b> <br />
<img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLDT72n65rODskwm0Rw1UUqulYixIvXxCVwjZ2-lzT_hbsKfv6po-lGIITSWH6fTeIeXXcYcHIximgFkwKR20QNqcBY-VopCnTy5i3XD3tGzuEY7kefI8Z9k8x6H90ubasFwm0Jiju2zE/s320/Worm+holes+image.png" /> <br /><br />Worm holes: Elongated or tubular cavities formed by trapped gas during the solidification of the weld metal which can occur singly or in groups. <br /><br /><b>Causes</b>:
<ol>
<li>Gross contamination of preparation surface</li>
Prevention: Introduce preweld cleaning procedures
<li>Laminated work surface</li>
Prevention: Replace parent material with an unlaminated piece
<li>Crevices in work surface due to joint geometry</li>
Prevention: Eliminate joint shapes which produce crevices </ol>
<br />
Worm holes are caused by the progressive entrapment of gas between the solidifying metal crystals (dendrites) producing characteristic elongated pores of circular cross-section. These can appear as a herringbone array on a radiograph and some may break the surface of the weld. <br /><br />
<b>
<li>Surface Porosity</li>
</b> <br /><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicEpA8jSsBZwUIyN62u-MFgpGe9m8ehW9Kg_Mu1rop-iA136TrUKX1hnXp8Ky-LhtMt0xUjs_A6VVZOu96GmPgZkEO32pblyXnIfbjeEiimSjKHDM-SuzLNWcygSDYR4syEETrjIqpW7c/s320/Surface+Porosities+image.png" /><br />
Surface Porosity: A gas pore that breaks the surface of the weld.
<br /><br /><b>Causes</b>: <br /><ol>
<li>Damp or contaminated surface or electrode</li>
Prevention: Clean surface and dry electrodes
<li>Low fluxing activity (MIG/MAG)</li>
Prevention: Use a high activity flux
<li>Excess sulphur (particularly free-cutting steels) producing sulphur dioxide</li>
Prevention: Use high manganese electrodes to produce MnS. Note free-cutting steels (high sulphur) should not normally be welded
<li>Loss of shielding gas due to long arc or high breezes (MIG/MAG)</li>
Prevention: Improve screening against draughts and reduce arc length
<li>A shielding gas flow rate that is too high results in turbulence (MIG/MAG, TIG)</li>
Prevention: Optimise gas flow rate </ol>
<br />
<b>
<li>Crater Pipe</li>
</b><br /><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPx7hf1ysEULMtQWDsI5ns6Ql6A-sPe-D2BGkobxiLI0e9XbW4CfwYtEsX3cc6f2V-tDByj95dm13gs2JDbHFPY9NlpSPHDp_RBgidC1W8rgQ7Qr6fpAOs4hcEuuOMpar79Cn78yfHdH8/s320/Crater+pipe+image.png" /> <br /><br />Crater pipe: A shrinkage cavity at the end of a weld run usually caused by shrinkage during solidification. <br /><br /><b>Causes</b>: <br /><br />
<ol>
<li>Lack of welder skill due to using processes with too high a current </li>
Prevention: Retrain welder
<li>Inoperative crater filler (slope out) (TIG) </li>
Prevention: Use correct crater filling techniques </ol>
<ol><br /></ol>
Crater filling is a particular problem in TIG welding due to its low heat input. To fill the crater for this process it is necessary to reduce the weld current (slope out) in a series of descending steps until the arc is extinguished.
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-70409294601719419522016-06-08T10:46:00.002+07:002016-06-08T10:46:59.826+07:00Definition and Types of Cracks according to BS EN ISO 6520-1<div style="text-align: justify;">
<b><br /></b>
<b>Crack</b> is imperfection produced by a local rupture in the solid state, which may arise from the
effect of cooling or stresses. Cracks are more significant than other
types of imperfection as their geometry produces a very large stress
concentration at the crack tip making them more likely to cause fracture.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Types of crack:</div>
<ul>
<li style="text-align: justify;">Longitudinal.</li>
<li style="text-align: justify;">Transverse.</li>
<li style="text-align: justify;">Radiating (cracks radiating from a common point).</li>
<li style="text-align: justify;">Crater.</li>
<li style="text-align: justify;">Branching (group of connected cracks originating from a common crack).</li>
</ul>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
These cracks can be situated in the:
</div>
<ul>
<li style="text-align: justify;">Weld metal.</li>
<li style="text-align: justify;">HAZ.</li>
<li style="text-align: justify;">Parent metal.</li>
</ul>
<div style="text-align: justify;">
<i>Exception: Crater cracks are found only in the weld metal.</i></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Depending on their nature, these cracks can be:</div>
<ul>
<li style="text-align: justify;">Hot cracks(ie solidification or liquation cracks).</li>
<li style="text-align: justify;">Precipitation induced cracks(ie reheat cracks present in creep resisting steels).</li>
<li style="text-align: justify;">Cold cracks(ie hydrogen induced cracks).</li>
<li style="text-align: justify;">Lamellar tearing.</li>
</ul>
<div style="text-align: justify;">
<b>Hot cracks</b></div>
<div style="text-align: justify;">
Depending on their location and mode of occurrence, hot cracks can be:</div>
<ul>
<li style="text-align: justify;">Solidification cracks: Occur in the weld metal (usually along the
centreline of the weld) as a result of the solidification process.</li>
<li style="text-align: justify;">Liquation cracks: Occur in the coarse grain HAZ, in the near vicinity of
the fusion line as a result of heating the material to an elevated
temperature, high enough to produce liquation of the low melting point
constituents placed on grain boundaries.</li>
</ul>
<div style="text-align: justify;">
<b>Solidification cracks</b></div>
<div style="text-align: justify;">
<img alt="crack" border="0" height="172" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj54cV3z9vWmmNGskL5ZAbv-6grd-Z_VURb6fvk50n-4xB4QSq4wwOQIVcGs5cm7W32YwgiLFPZ4hM6GLdsDXJsgfEdbRtJ7C1ghYl3W3o7ouBN0zJWCLc_aRiOqq6nwfS3qX1GnMzYvEs/s200/solidification+crack+image.png" title="solidification crack image" width="200" /></div>
<div style="text-align: justify;">
<br />
Generally, solidification cracking can occur when:</div>
<ul>
<li style="text-align: justify;">Weld metal has a high carbon or impurity (sulphur, etc) content.</li>
<li style="text-align: justify;">The depth-to-width ratio of the solidifying weld bead is large (deep and
narrow).</li>
<li style="text-align: justify;">Disruption of the heat flow condition occurs, eg stop/start condition.</li>
</ul>
<div style="text-align: justify;">
The cracks can be wide and open to the surface like shrinkage voids or
sub-surface and possibly narrow. Solidification cracking is most likely to occur in compositions and result in a
wide freezing temperature range. In steels this is commonly created by a
higher than normal content of carbon and impurity elements such as sulphur
and phosphorus. These elements segregate during solidification, so that
intergranular liquid films remain after the bulk of the weld has solidified. The thermal shrinkage of the cooling weld bead can cause these to rupture and
form a crack.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<img alt="" border="0" height="151" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXlL20Z9lx2Q4cdqDf7v2G-NgYPzdQgNU_HWUsLTrqpY87i-kVKMxq7zxNMxu3lxPiTA7VQVgo6LASqEemlr_KVCCxjGTAiY5M-2-Ia6mgUSaWGxf1lyQ15Ek7QsM-9WKxBrKi2TewVEY/s200/thermal+shrinkage.png" title="thermal shrinkage image" width="200" /></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
It is important that the welding fabricator does not weld on or near metal
surfaces covered with scale or contaminated with oil or grease. Scale can
have a high sulphur content and oil and grease can supply both carbon and
sulphur. Contamination with low melting point metals such as copper, tin,
lead and zinc should also be avoided.
</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b>Hydrogen induced cracks</b></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE-rhq-5AJHIRCM3ILFGv7Tk2mW2Q-_OlcuEoakI8Hv6eIG2KPYyM98bC-kNJLfd6r7zu2-qqjMeSEzP5txXzaA_D-FRkrnrq7k6ONWUrV3-mX5vJ_eQ6LLxb67amXygzYaGTthNttcAw/s200/root+or+underbead+crack.png" style="margin-left: auto; margin-right: auto;" width="190" /></td><td style="text-align: center;"><img border="0" height="193" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgt54G9OXLenvoj_qCP-vlye5F5qYcXoZKY5WaZdpzoFe5x9iyMTjGHy7IrR_-FRLamGwIA4ZxcOoi27N08-nhKIk9orN6QVdSemtvmYlbYKKW1urey3OF3H1r8CAu8Mnzd2y53pwhbrQQ/s200/toe+crack.png" style="margin-left: auto; margin-right: auto;" width="200" /></td></tr>
<tr><td style="text-align: center;">Root (underbead) crack</td><td style="text-align: center;">Toe crack</td></tr>
</tbody></table>
<div style="text-align: justify;">
Hydrogen induced cracking occurs primarily in the grain coarsened region of
the HAZ and is also known as cold, delayed or underbead/toe cracking. It
lies parallel to the fusion boundary and its path is usually a combination of
inter and transgranular cracking. The direction of the principal residual
tensile stress can in toe cracks cause the crack path to grow progressively
away from the fusion boundary towards a region of lower sensitivity to
hydrogen cracking. When this happens, the crack growth rate decreases
and eventually arrests.<br />
<br />
Four factors are necessary to cause HAZ hydrogen cracking:<br />
<ul>
<li>Hydrogen level > 15ml/100g of weld metal deposited</li>
<li>Stress > 0.5 of the yield stress</li>
<li>Temperature < 300°C</li>
<li>Susceptible microstructure > 400HV hardness</li>
</ul>
<div style="text-align: center;">
<img alt="hydrogen cracking" border="0" height="304" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjw8MyS7rAkQV5KkAOP3AKyuu2J_kVLUnl0VNL_9HC534HtDbuBPuPVBu8p-qJt2TkkRy29hhPcu2BpECNy0wcBUoOhCvgon6EoFkkkm1DjG9I0rsyTdAXI-sxHgbkAMI1ihgdpLR4g-hM/s320/four+factor+cause+of+hydrogen+cracking.png" title="factors of hydrogen cracking image" width="320" />
</div>
<br />
If any one factor is not satisfied, cracking is prevented, so can be avoided
through control of one or more factors:
<br />
<br />
<ul>
<li>Apply preheat slow down the cooling rate and thus avoid the formation of susceptible microstructures.</li>
<li>Maintain a specific interpass temperature (same effect as preheat).</li>
<li>Postheat on completion of welding to reduce the hydrogen content by allowing hydrogen to diffuse from the weld area.</li>
<li>Apply PWHT to reduce residual stress and eliminate susceptible microstructures.</li>
<li>Reduce weld metal hydrogen by proper selection of welding
process/consumable (eg use TIG welding instead of MMA basic
covered electrodes instead of cellulose).</li>
<li>Use a multi-run instead of a single run technique and eliminate
susceptible microstructures by the self-tempering effect, reduce
hydrogen content by allowing hydrogen to diffuse from the weld area.</li>
<li>Use a temper bead or hot pass technique (same effect as above).</li>
<li>Use austenitic or nickel filler to avoid susceptible microstructure
formation and allow hydrogen to diffuse out of critical areas).</li>
<li>Use dry shielding gases to reduce hydrogen content.</li>
<li>Clean rust from joint to avoid hydrogen contamination from moisture
present in the rust.</li>
<li>Reduce residual stress.</li>
<li>Blend the weld profile to reduce stress concentration at the toes of the
weld.</li>
</ul>
<b>Lamellar tearing</b><br />
<img alt="crack lamellar" border="0" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0FtV4252LWmUQ0Lk-9V10yF2OKKbirx_AznWO3e0J2QDPnT05NoC68Wn7VvoBm6NFlUinVBSLkvpy_5-WwSC9xlGGjAr-Hm_Zlhz7SMQpMaxsyQA54U27e_wsuRcLlHKO-I0KB515ySw/s200/Lamellar+tearing.png" title="Lamellar tearing image" width="200" /><br />
<br />
Lamellar tearing occurs only in rolled steel products (primarily plates) and its
main distinguishing feature is that the cracking has a terraced appearance.<br />
<br />
Cracking occurs in joints where:
<br />
<ul>
<li>A thermal contraction strain occurs in the through-thickness direction of
steel plate.</li>
<li>Non-metallic inclusions are present as very thin platelets, with their
principal planes parallel to the plate surface.</li>
</ul>
Two main options are available to control the problem in welded joints liable
to lamellar tearing:
<br />
<br />
<ul>
<li>Use a clean steel with guaranteed through-thickness properties
(Z grade).</li>
<li>A combination of joint design, restraint control and welding sequence to
minimise the risk of cracking.</li>
</ul>
</div>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com1tag:blogger.com,1999:blog-5462242472424491265.post-73792953039693996632016-06-05T04:41:00.000+07:002016-06-09T10:13:27.196+07:00Welding Imperfections according to BS EN ISO 6520-1Definitions:<br />
<b>Imperfection</b> Any deviation from the ideal weld.<br />
<b>Defect</b> An unacceptable imperfection.<br />
<br />
<b>BS EN ISO 6520-1</b> standard classifies the geometric imperfections in fusion welding
dividing them into six groups:
<br />
<ol style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;">
<b>
<li>Cracks. </li>
</b>
<img alt="longitudinal crack" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwaQhKomzY9BhyphenhyphennPOJBBnRm-f2Sn9b02gKytDl9W026nMWNvsalf4tMorUaRHatFBe5d6szgqelhSe4fQBWqjaDqZbgRMMylWnt90GOk9pbGob93J0FD5CrEEmjnUS5BpJXGlcX8mulP0/s200/cracks+image.jpg" title="Cracks image" /><br />Imperfection produced by a local rupture in the solid state, which may arise from the
effect of cooling or stresses. Cracks are more significant than other
types of imperfection as their geometry produces a very large stress
concentration at the crack tip making them more likely to cause fracture.<br /><br />
<i>also read</i>: <a href="http://learnweldinginspector.blogspot.co.id/2016/06/definition-and-types-of-cracks.html">Definition and Types of Cracks according to BS EN ISO 6520-1</a>
<b>
<li>Cavities. </li>
</b>
<img alt="cavities imperfection" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhY0UBcabR-9FEGIkteKTqJchSHOHdAgG3DZkpzLXRlmRIbbgvCoj0LT8SH0Zaw46TVvBm9chf2Oh_yhiGKZU4faXzWANLvQXDZTojpuQPGPTkduvghFTy_4PkLw5egtDmEADI5TqIJjGM/s200/cavities+image.jpg" title="cavities image" /><br />Cavity may be either gas cavity due to entrapment of gas or due to shrinkage caused by shrinkage during solidification.<br /><br />
<b>
<li>Solid inclusions. </li>
</b>
<img alt="tungsten inclusion" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpOUWFxA_SHF-q1aaLVgK5V4QuNp4grLtz0kXBv3476EltRnsziWUIbhvcFN_IXznl8cBmmSwME7RsuI9Uz5vb4QTh6FMZMEDD7aqFvP3S1QV8xUVyxUSQDPpljHLOofNQhWp6d4zeX4I/s200/solid+inclusion+image.jpg" title="solid inclusion image" /><br />Solid foreign substances trapped in the weld metal<br /><br />
<b>
<li>Lack of fusion and penetration.</li>
</b>
<img alt="lack of penetraton" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnDf8w8rEhz_QqA69A3OgNhAWkwxEPY6tPwfr_c24cgBMOpCyL9odZ28KksqI3K-_dIPOo6t9wRWzGoLp4rFubOhKqxyIce4wOAK1Iztme9EobhlQ_ub6dVdMf7SD8GtRs24Sv2JfVmQU/s200/Lack+Of+Fusion+image.JPG" title="Lack of fusion image" /><br />Lack of union between the weld metal and the parent metal or between the
successive layers of weld metal.<br /><br />
<b>
<li>Imperfect shape and dimensions. </li>
</b>
<img alt="undercut" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKqpnuLKYaZCzOu5VPbTs4HKdALWQ0aN4s8HonlgbLX2qJj5_yW9B2jluZYR5YO0oiXFl9ArZuIcwvU9RNTpUzMl-t2BoXiahyphenhyphenhvw8aKpHsSBPAzGvJDoBNXzSGD9czNdEkCetXVNDgyI/s200/undercut+image.jpg" title="imperfect shape image" /><br />An irregular groove at the toe of a run in the parent metal or previously
deposited weld metal due to welding. Characterised by its depth, length and
sharpness.<br /><br />
<b>
<li>Miscellaneous imperfections.</li>
</b>
<img alt="spatter" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9sFRYZQuO8oqMZpo1fG99qm1sk4xp_NaanJ5aS5-N8hB5ukunICkdZ9PNLAOA68BxPcQ1zh4VSnp481Muxgt_ESxLXPOt1V7FNxZfd5N48f_sChlcZu5XYmdhdudj051qXgyq9MaOZaw/s200/spatter+image.jpg" title="miscellanous image" /><br />Local damage to the surface of the parent metal adjacent to the weld.
</ol>
<br />belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-26225311906660771712016-06-02T19:29:00.000+07:002016-06-02T19:29:05.943+07:00Types of Welding Preparation Refer to Standard BS EN ISO 9692<ol style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;">
<b>
<li>Open Square Butt Preparation</li>
</b><img alt="Open Square" border="0" height="60" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjK_8xj9lfxSmjdxbh2xJn2Yo1zctmS22IKUCmh9OmD_cTJ7lHVKrueGFTTFhOlZPuvp56ZtdH5tP8hyphenhyphenrjA8_XRJoTU-lEcFZXIzjkgL-3msp122-e4rcvVi3oLxNmuFqpqVWLKIbt71Jw/s400/Open+Square+Butt+Preparation.png" title="Open Square Butt Preparation Image" width="400" /><br />
Used for welding thin components from one or both sides. If the root gap is zero (ie if components are in contact), this preparation becomes a closed square butt preparation (not recommended due to problems caused by lack of penetration)!<br /><br />
<b>
<li>Single V Preparation</li>
</b><img alt="Single V" border="0" height="218" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj447NNTEnIoMA4f3wLxC0iPUTZtaT85r-ASyu16ozjOMXA4-3Tz-BPEOXuiiCY6kap64v3UnO8yBtCtTLNRJ9N6PynrrtYWgzXCe0AjFnsZguBBV2-BwBvp4cS66yBERxscOWc_B01MxY/s400/Single+V+preparation.png" title="Single V Preparation image" width="400" /><br />
One of the most common preparations used in welding and can be produced using flame or plasma cutting (cheap and fast). For thicker plates a double V preparation is preferred since it requires less filler material to complete the joint and the residual stresses can be balanced on both sides of the joint resulting in lower angular distortion.<br /><br />
<b>
<li>Double V Preparation</li>
</b><img alt="Double V" border="0" height="132" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3IT8kDAiZMJBMeN5YbbBK9iADEScJZeVX4vz-fjAZ718S6X0zVlA_NSGWQOMx_NuUaNfM9J9U-hpF1sTZyC3TzfxWNZoyHVVvp9hSJ4rDo2mkdBdQuEmgq5G3EMCYobElPZdZRvltbOU/s400/Double+V+preparation.png" title="Double V Preparation image" width="400" /><br />
The depth of preparation can be the same on both sides (symmetric double V preparation) or deeper on one side (asymmetric double V preparation). Usually, in this situation the depth of preparation is distributed as 2/3 of the thickness of the plate on the first side with the remaining 1/3 on the backside. This asymmetric preparation allows for a balanced welding sequence with root back gouging, giving lower angular distortions. Whilst a single V preparation allows welding from one side, double V preparation requires access to both sides (the same applies for all double sided preparations).<br /><br />
<b>
<li>Single U Preparation</li>
</b><img alt="single U welding" border="0" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUQBA365lm1x3apWnksZCtHEkXt5GXytQjXDvwpW9ZdsoovxRe0eCkcLhzO52NofYILQirmNOGX5LXDh2UuEgg4guHww4aC0uX8L0HDLL_HkrxnE3drURfPO2ce0yQq5pvcIh5KZ-F7dE/s400/Single+U+preparation.png" title="Single U Preparation image" width="400" /><br />
U preparations can be produced only by machining (slow and expensive), however, tighter tolerances give a better fit-up than with V preparations. Usually applied to thicker plates compared with single V preparation as it requires less filler material to complete the joint, lower residual stresses and distortions. Like for V preparations, with very thick sections a double preparation can be used.<br /><br />
<b>
<li>Double U Preparation</li>
</b><img alt="double U welding" border="0" height="146" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjK3y1bOdlJI9dA3qreaLDvhupOPIWNbgzMbl4FOM0wXaURDNj95zi3sN4V0W-BQJx4_TsEknzNlrnX5IflY9duYhhTl_VugcP2APouZmq3AyUX8a1KPzsKQtzYlswJWnAw7KxVau_e0ss/s400/Double+U+preparation.png" title="Double U Preparation image" width="400" /><br />
Usually this type of preparation does not require a land, (except for aluminium alloys).<br /><br />
<b>
<li>Single V Preparation With Backing Strip</li>
</b><img alt="backing strip" border="0" height="116" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOhLN4937rTSdsbTygb6AYw8XEoyt3FlJf3P_jIwZDUi2w7cRs_vTIMfG_jWsZuX3fuNbBcxEOylz8ZE3pYbQa_1Wu7LqJCQi5GJt6wNqLN7Cc4X8iTNHmQ1eFtqmkJK2iI4lMNV5PMBk/s400/Single+V+preparation+with+backing+strip.png" title="Single V preparation with backing strip image" width="400" /><br />
Backing strips allow production of full penetration welds with increased current and hence increased deposition rates/productivity without the danger of burn-through. Backing strips can be permanent or temporary. Permanent types are made of the same material as being joined and are tack welded in place. The main problems with this type of weld are poor fatigue resistance and the probability of crevice corrosion between the parent metal and the backing strip. It is also difficult to examine by NDT due to the built-in crevice at the root of the joint. Temporary types include copper strips, ceramic tiles and fluxes.<br /><br />
<b>
<li>Single Bevel Preparation</li>
</b><img alt="single bevel welding" border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdRk0Ay0aoXsPLOhHBj6dNZ1ABgCbtSYEKTC_EeRSPN7BRKCQJq0YCG6AMAqFDOKXF3sLC0DbOM-LtK_Uz7hrNvLLQUS6gtJXjkCpuLfsuZAmbNhQr-WohUmmfQAf7XeUIa5koFc8Muus/s400/Single+Bevel+preparation.png" title="Single bevel preparation image" width="400" /><br /><br />
<b>
<li>Double Bevel Preparation</li>
</b><img alt="double bevel welding" border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8uZrxp7TIC32ki2M27Y_m4meKCCjvnnS3b3kN47sQ7H4i6edquFhj1gfi5pBlikdyPPs8h5xCzQG2WDURf6u46SnMNnkMmfsT-b1MiYeWvaA3sDS0uHCSiFHyKVD3w0mbi4Z3-hMHIqs/s400/Double+Bevel+preparation.png" title="Doble bevel preparation image" width="400" /><br /><br />
<b>
<li>Single J Preparation</li>
</b><img alt="single J welding" border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip-up5Kej4e721eFdMUhL0wVuJcyTW8NahKGv0UlgB6t-ko39P75QbBMSE9ZR_TLxquGQACuCCyJ-SDFxZ69D6kBS1Vf-Rdl25Sv9EGQw27AUiRuiA1wIUiDZzHj-L0MizG33foQa2CZk/s400/Single+J+preparation.png" title="Single J preparation image" width="400" /><br /><br />
<b>
<li>Double J Preparation</li>
</b><img alt="Double J welding" border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjg2DzLyDyy822ASVp4UvfZxqkA8KXwcSzA-N0frfqa44UX1EM8QnGsYigZwVPMgbfHwlovmiBckFBK9jH_uPxJGBKV4eCrG2h-FklAuZTODNCUoXzW_fEMKNN6wy8RkHJN6wLZkG0yjhM/s400/Double+J+preparation.png" title="Double J preparation image" width="400" />
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-86941793839630336372016-05-28T17:27:00.000+07:002016-05-28T17:27:38.024+07:00Typical Duties of Welding Inspector After welding<b>Duties after welding:</b><br />
Check:<br />
<ol>
<b>
<li>Weld Identification</li>
</b><img alt="marking welding" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgn48bo0bUwmOR_2H7VvomR4JJCE612DumHxDA55HhmAH4WHmX6_iuUOMLJUIirJyiCq31ZArzxNNz87svZMWQFyGAC5EkO7Wg-uStGzzvgb-JFGbJ6mWjpNVTLlYBULOG16OfHq_XXtn4/s200/welding+identification+image.gif" title="welding identification image" /><br />
Each weld is marked with the welder's identification and is identified in accordance with drawing/weld map.
<br /><br />
<b>
<li>Weld appearance</li>
</b><img alt="weld face" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQ_W3XieJNr67bfE-eGakq1LON0OMoez06qkJF38ppxXu0PX2klbJLHQ-6VQ2TZ5uz7BXFPUkPnVf3w7Tv2meY9__DpX8lOKmXEC-l-3DgKuMZtdHEko60VINDLeNPZ5u4_0aIZkehXek/s200/welding+appearance+image.jpg" title="welding appearance image" />
<ul>
<li>Ensure welds are suitable for all NDT (profile, cleanness, etc).</li>
<li>Visually inspect welds and sentence in accordance with Code.</li>
</ul>
<br />
<b>
<li>Dimensional survey</li>
</b><img alt="inspection weld" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2CbFrKwicAoGPAotRB5d_lX4E5IHplWnx7k4xd7808_P9GAZKWH1S8rOQ8ipucN_0is0GlRNo4BFuyWM0mCmQ2oQ5BMCe-0f-p6wv9feOAFQvgivYbC_ZGTfreFRIBniP-vJBGA1COOg/s200/weld+dimension+image.jpg" title="Dimensional Survey image" /><br />
Check dimensions are in accordance with drawing/Code.
<br /><br />
<b>
<li>Drawings</li>
</b><img alt="engineering drawing" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh75LfvQad0kSw_TLaJplz6FH852XX7LGaeRftAdghglAdxnTULGuwnAjIGeZP6AWSiuYQ5VjHkZ3C4y0ddLyCdPHHfJIKeNeo6ZMlB1nWtonXD-CaSXmJKudDSywJsO4-6ekytcZekayo/s200/engineering+drawing.jpg" title="drawings image" /><br />Ensure any modifications are included on as-built drawings.
<br /><br />
<b>
<li>NDT</li>
</b><img alt="non destructive test" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcXgqntDxF8pagh7bjm1qcjJw-z-Jn2KWgZ7sSUxgJNYaejks6qaDzU-xOjygrxoh6nrj_m-0H8oIe6FeROLxNf4lwoNp4A5UrWs6F6U0ENg6D4y9mjxisv05i7VL5ewV0FQ9qmRap2kU/s200/ndt+image.jpg" title="ndt image" /><br />Ensure all NDT is complete and reports are available for records.
<br /><br />
<b>
<li>Repairs</li>
</b><img alt="repairs" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3izieZjZqr2Y9c0GnQVGE1EniPK5_kBtK39HdI8_tnZwMcpeQi3x36DTd-quVLTRPCnVGIKKWNwia8EvVMB500iOwhaQuopqJPHfYM0Dl-f3ZwNRiVfLaV22-jiXkwVoeJ-xk_iVg4DM/s200/repair+weld+image.jpg" title="repair welding image" /><br />
Monitor in accordance with the procedure.
<br /><br />
<b>
<li>PWHT (if required)</li>
</b><img alt="post weld heat treatment" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzhMvRlMqSfZBbDCK9se3rzP1EXUzr1C8v6h1fp5PTAYobcXioEWIx-hmoLcF-KLJrY2I2HNifWYi5ebtj775qaNdUS7gH1YZwV112ss7MU0HqLOthFQaVFPqUC_CouzorzqKdlu7Yafs/s200/PWHT+image.jpg" title="PWHT image" /><br />
Monitor for compliance with procedure (check chart record).
<br /><br />
<b>
<li>Pressure/load test (if required)</li>
</b><img alt="leak test" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguYrd5XPL-UuBcDIlwXrm9sU921fLk1kdg7oNygrT2yewChd8mUfxZWkWeh3VK_zEcEuuBFPP8172x1A_RDjZ4tsXT7eYaCK12LYX3QEITptEpMxXV_h-C08fjCeszNPgMmNTfCuUwJlg/s200/pressure+test+image.jpg" title="pressure test image" />
<ul>
<li>Ensure test equipment is calibrated.</li>
<li>Monitor test to ensure compliance with procedure/Code.</li>
<li>Ensure reports/records are available.</li>
</ul>
<br />
<b>
<li>Documentation records</li>
</b><img alt="inspection report" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip_uiGnC_c_8GlsRX4j_ZDtTkHthtMDeGxFwnGKk-Hqs741jV8B3eiwBoUxTnjHUPMIhX-ccKqhNSgzYrNkkeQVczUdesyWw6VIa84_0rZwDOzJI3wu6o5gers7FDMTj5zKwvleVX1Q0Y/s200/inspection+report+image.png" title="documentation records image" /><br />
Ensure all reports/records are completed and collated as required.
<br /><br />
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-23324703939459464722016-05-28T01:15:00.002+07:002016-05-28T01:15:39.823+07:00Typical Duties of Welding Inspector During welding<b>Duties during welding:</b><br />
Check:<br />
<ol>
<b>
<li>Site/ field welding</li>
</b><div style="text-align: center;">
<div style="text-align: left;">
<img alt="field welding" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjr0Tp3qYToTd8kcKEuUk7MwQih1IBoz9ksmGy8fR8XeL_kh_wnw336A3vKjrcboa6gZ6JErS0P2XSGSKtP8X2CcT5tCJUh68pXpR245_jh-1wntr14ICkBlGDR5J9-PC-sdjDRdRt4FyI/s200/site+field+weld+image.jpg" title="site project image" /></div>
</div>
Ensure weather conditions are suitable/comply with Code (conditions will not affect welding).
<br /><br />
<b>
<li>Welding Process</li>
<div class="separator" style="clear: both; text-align: left;">
<img alt="welding tig image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHuW-ieQGX-U2SpAxlBvGvEbAd6NNO7sQlleaHZW_dgFaEvGd0qsPwm454WOAxEa_PtSdG3H87FDnB_nN3twrkG24m_QtkcTGqXoaZL-iEXv9QwPoFus3gvcc5xnkvyICWUMDxv1KHKY0/s200/welding+process+image.jpg" title="welding process image" /></div>
</b>Ensure welding process in accordance with WPS.
<br /><br />
<b>
<li>Preheat (if required)</li>
</b><div class="separator" style="clear: both; text-align: left;">
<img alt="Preheat" border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpAxWBabDM7v_RAluPmp8MIvjAjNiJtiTZqOhqKvuHMEfaGs8BPhRge8L4msmitYsbl9uuMFaxr40m_oCTmIbBK74a92Xnqj03Rqq8_5t-CKwLGPWD2wHD4jcwlAyMm8hoRsDqFQ6Hb14/s200/preheat+image.jpg" title="Preheat image" width="200" /></div>
Ensure preheat minimum temperature is being maintained in accordance with WPS.
<br /><br />
<b>
<li>Interpass Temperature</li>
</b><div style="text-align: left;">
<img alt="stick temperature" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv_LAPW-yc1JE_M01rhVimPTg7DBObVVOySdied5JeRTUMps2riyhHOUOKje7mNU6R9flmNX9NHSNqumJx_ls5IrxtpCDIJnkMTuyqICjn1Y-ilZtjBYWRxPzJfckbRecf9IMUJl4yNII/s200/intepass+temperature+image.jpg" title="interpass temperature image" /></div>
Interpass maximum temperature is in accordance with WPS.
<br /><br />
<b>
<li>Welding Consumables</li>
</b><div style="text-align: center;">
<div style="text-align: left;">
<img alt="electrode" border="0" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVvkVlM2zMhvNUkt-m9GSMwlQlOD7ZGVsIAMb9KfmocV-Nv-EW4O5DpGwl9trOwufHLcj7-tOdDv5j52NwXj9B-j0i5tgoXGloN94mRIFfUP7NHEC7gwUxKkTZQSK728kHL68D0umf8sQ/s200/welding+consumables+image.jpg" title="welding consumables image" width="200" /></div>
</div>
Welding consumables in accordance with WPS and being controlled as procedure.
<br /><br />
<b>
<li>Welding Parameters</li>
</b><div style="text-align: left;">
<img alt="voltage amperage iwelding image" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimBAacsdfmZ6WzQxRJoexjCUpeuEYUwCnBfJDkPeNzjwxGBP1EO11I-eNn_AdLSPSzRelmDDAqUC2RaX_7TxDkRAYycU3RYOHEcIdHNwS41dbIrOYiERuwYnkSzKDu9DTx-2c7Abl8jJE/s200/welding+parameter+image.png" title="welding parameter image" /></div>
Current, volts, travel speed are in accordance with WPS.
<br /><br />
<b>
<li>Root Run</li>
</b><img alt="root pass" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSA6Yt8_e38eSVqMKsEOE26XXOPh-zTcwCi9DWuzF_UfAqcGOW0veT4f3b6ihBf6241vaCpIsRWVB8xrHCHYUAHfJAFp_Kl8sNqn93Xqg29F2h1ZWOzmqPOUKaIwTO_2p-IikHZEE2xEE/s200/root+run+image.jpg" title="root run image" /><br />
Root run visually acceptable to Code before filling the joint (for single sided welds).
<br /><br />
<b>
<li>Gouging/ Grinding</li>
</b><img alt="gouging grinding" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBixt8Asz3cK0SqSjqe8WWNuHJfTiEhWqevithd2tb_SpipObhRMMDxCtBoWoPqH_V5DZoqGTNpPVTt3Aw_Emkp3fgEXICfU6Wo8rtn-T6CJRFkn7l1xzR76i4or-qfiWUZOZ2sFHBH70/s200/Gouging+image.jpg" title="gouging image" /><br />
Gouging/ grinding by an approved method and to good workmanship standard.
<br /><br />
<b>
<li>Inter-run Cleaning</li>
</b><img alt="cleaning welding" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnmz_JD1wtek7Qo1GB2HmZWFFvMGxwrI4WvA8S8TzPvudi9JIJkDFxFsxaxuLg4e7HAIzsahg7B5h9NrBYXTIniyOOih2lmBKKtgy1bWBoswkfH4Tl71tj-8Upq9IMZtzf3naPHfU3M58/s200/inter+run+cleaning+image.jpg" title="inter run cleaning image" /><br />
Inter-run cleaning to good workmanship standard.
<br /><br />
<b>
<li>Welder</li>
</b><img alt="welder" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2H3wXi457QLyl7VICidACMfSs4oUGIHQlS2pWmtDn6qezP2I9Ta8eKg62C0OXQnG4GdBaMncQHCkraqu_HtfS6QuYwc4wbKnRDP0wJxMHBUXfcu0VdweyPV593dtCLKkpiXc2fSrer88/s200/welder+image.jpg" title="welder image" /><br />
Welder on the approval register/qualified for the WPS being used.
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com1tag:blogger.com,1999:blog-5462242472424491265.post-42719664497353936422016-05-25T17:06:00.000+07:002016-05-28T10:39:28.285+07:00Typical Duties of Welding Inspector Before welding<b>Duties before welding</b>:<br />
Check:<br />
<br />
<ol><b>
<li>Material</li>
</b> <div class="separator" style="margin-left: 1em; margin-right: 1em; text-align: center;">
<img alt="Piping rack" border="0" height="167" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjtgsa9q8hLFUCV6TQNGUQA4OYhF1GntldkZVwnKSsafsFPjllh4z2Ezy77i94ll0F-diImIinlZ31hKhZHiY1bBpDekUmEbdlDmZLFY313vLFXS5m9xyfLtwltNoCdZ0534kHEZK2t38/s200/material+piping+image.jpg" style="margin-left: auto; margin-right: auto;" title="Material Inspection image" width="200" /></div>
Ensure material: <ul>
<li>In accordance with drawing/WPS.</li>
<li>Identified and can be traced to a test certificate.</li>
<li>In suitable condition (free from damage and contamination).</li>
</ul>
<br />
<b>
<li>WPSs</li>
</b> <div class="separator" style="margin-left: 1em; margin-right: 1em; text-align: center;">
<img alt="WPS" border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghDmUIujsf2mWZ_0numx5plBDykO4esdsLqcSRQ-RoGxoH2VDDgSb85UBagbj0_1JDxDz211wP2C1SRPBl6oEVutke2FU8Y_dKY3E_nG_ZUXDd6KetN8EnvWZpAnbFFr-OzMsgbS-M4VM/s200/Welding+procedure+specification+image.png" title="Welding Procedure Specification image" width="143" /> </div>
Ensure WPSs approved and available to welders (and inspectors). <br /><br /><b>
<li>Welding equipment</li>
</b><div class="separator" style="clear: both; text-align: center;">
<img alt="welding equipment" border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDbNu0aD9iMZ3bUyxJYSUDVWBHUO9mikaXj6qPoZRoR4iLpcpXRRdB-jjxgXk9kVKMR2l69ooQNeqL-6WjiP2FZJeZmzkx0HGs9tnO-xBVYVN_Lx91pRS4WlYz4aJu631PYBhXTuCNRA4/s200/welding+machine+image.jpg" title="welding machine image" width="196" /></div>
Ensure Welding equipment in suitable condition and calibrated as appropriate. <br /><br /><b>
<li>Weld preparations</li>
</b><div class="separator" style="clear: both; text-align: center;">
<img alt="engineering drawing" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo7Xh_-i0pukjayFkGU1JxHX1oyEAyS4zCGZkOYJD87kJ1iiohtGbDVfbhibXjfDw748hq9TdpG1vZZqMOtUDlynswifur4l-f99kGJ_vLoyZcblstB2S_Cq14Dc6U_chyrMhNIdMGl4U/s200/engineering+drawing.jpg" title="welding preparation image" /></div>
Ensure Welding preparations in accordance with WPS (and/or drawings). <br /><br /><b>
<li>Welder qualifications</li>
</b> <div class="separator" style="clear: both; text-align: center;">
<img alt="welder test " border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjftTu3rJCJ-2aHxfeNVjKkIKJ5Eq47gpxdOytHwf2MpTaa3rtbfJIuxhzqdH311s1U1qSFa-cOIHXxQFAzt6i9cfQquZHD49EL1Jw2z1DFW1hbFuzdJ10-6_KAT9TH2aPyV3v0Zmu9FIE/s200/welder+qualification+image.jpg" title="welder qualification image" /></div>
Ensure Welding qualifications: <ul>
<li>Identification of welders qualified for each WPS to be used.</li>
<li>All welder qualification certificates are valid (in date).</li>
</ul>
<br />
<b>
<li>Welding consumables</li>
</b> <div class="separator" style="clear: both; text-align: center;">
<img alt="electrode" border="0" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVvkVlM2zMhvNUkt-m9GSMwlQlOD7ZGVsIAMb9KfmocV-Nv-EW4O5DpGwl9trOwufHLcj7-tOdDv5j52NwXj9B-j0i5tgoXGloN94mRIFfUP7NHEC7gwUxKkTZQSK728kHL68D0umf8sQ/s200/welding+consumables+image.jpg" title="welding consumables image" width="200" /></div>
Ensure those to be used are as specified by the WPSs, are stored/controlled as specified by the QC procedure. <br /><br /><b>
<li>Joint fit-ups</li>
</b><div class="separator" style="clear: both; text-align: center;">
<img alt="pipe to elbow" border="0" height="138" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhupv-xZ56D022nEbuX6TOyChXmOCDFYiOVeamLG86uWbuOuqkVvl6KywGxBoQIityFcM8M_EOUXDBuTLI06dOYQO0KiFupypo9u8srmPb67qui8gAkCyJRes03MhYK4e9Hls8jJPvmpxI/s200/joint+fit+up+image.jpg" title="joints fit up image" width="200" /></div>
Ensure Joint fit-ups in accordance with WPS/drawings tack welds are to good workmanship standard and to code/WPS. <br /><br /> <b>
<li>Weld faces</li>
</b> <div class="separator" style="clear: both; text-align: center;">
<img alt="preparation pipe face" border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihFKKYFAs0k6R4h2ELAmLPZMgVvTx_K0PVbdvATcufh7lwiWAKsaOocr2Pv9p2jWjcihFNN4taH7dKfkFh3AWXMbrAzgKPGC2vLigmamRncWlM9ic6wetDSo9xODoz2FzW4QhkDeQiBQo/s200/weld+face.jpg" title="pipe weld face image" width="200" /></div>
Ensure Weld faces free from defects, contamination and damage.<br /><br /><b>
<li>Preheat (if required)</li>
</b> <div class="separator" style="clear: both; text-align: center;">
<img alt="Preheat" border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpAxWBabDM7v_RAluPmp8MIvjAjNiJtiTZqOhqKvuHMEfaGs8BPhRge8L4msmitYsbl9uuMFaxr40m_oCTmIbBK74a92Xnqj03Rqq8_5t-CKwLGPWD2wHD4jcwlAyMm8hoRsDqFQ6Hb14/s200/preheat+image.jpg" title="Preheat image" width="200" /></div>
Ensure Preheat minimum temperature is in accordance with WPS. </ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-19952783185150511722016-05-23T22:04:00.000+07:002016-05-23T22:12:19.306+07:00Features of the Completed Weld<img alt="butt weld features" border="0" height="197" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhX3Wihpyp_5zAW832rCava_jJHU6x7wABm6Kt5OZvnSQeT3GucNUO57jrW-PCF4OvwHglvcaOSxR1rkKhpEw-E1xmJLE4tCY_HgFsLLrpaW6rsIlHXmzjJjlpN5A2h_YycyzJH3R2eZHQ/s320/Butt+Weld.jpg" title="complete weld butt weld image" width="320" /> <img alt="fillet weld features" border="0" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpnvq30VBDuKM6_1AN2v0QqDh8cWj4eTSBlgqUQ1ubGYejeaP3UU2sfkKRTkc2jNgcn1wzB-f7UwEMJgMCb79yO05SwIHEL-XyBEXUgHgoS7SM49-7qt6UdNHqd_6yayZwcqfuuPd-Rlo/s320/Fillet+Weld.jpg" title="complete fillet weld" width="320" /> <br />
<br />
<ol><b>
<li>Parent metal</li>
</b> Metal to be joined or surfaced by welding, braze welding or brazing
<b>
<li>Filler metal</li>
</b>
Metal added during welding, braze welding, brazing or surfacing <b>
<li>Weld metal</li>
</b> All metal melted during the making of a weld and retained in the weld <b>
<li>Heat-affected zone (HAZ)</li>
</b> The part of the parent metal metallurgically affected by the heat of welding or thermal cutting but not melted <b>
<li>Fusion line</li>
</b> Boundary between the weld metal and the HAZ in a fusion weld <b>
<li>Weld zone</li>
</b> Zone containing the weld metal and the HAZ <b>
<li>Weld face</li>
</b> The surface of a fusion weld exposed on the side from which the weld has been made <b>
<li>Root</li>
</b> Zone on the side of the first run furthest from the welder <b>
<li>Toe</li>
</b> Boundary between a weld face and the parent metal or between runs. This is a very important feature of a weld since toes are points of high stress concentration and often are initiation points for different types of cracks (eg fatigue and cold cracks). To reduce the stress concentration, toes must blend smoothly into the parent metal surface <b>
<li>Excess weld metal</li>
</b> Weld metal lying outside the plane joining the toes. Other non-standard terms for this feature are reinforcement and overfill </ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-81892493579069352442016-05-20T22:30:00.000+07:002016-05-20T22:30:25.478+07:00Welding Joint (according to BS EN ISO 15607)<ol>
<b>
<li>Butt Joint</li>
</b><br /><div class="separator" style="clear: both; text-align: center;">
<img border="0" height="78" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio-m1EVrgBxGln8ruoCDVSCvNAOfaZSOsVfTIVVy23f_AtMxhHmg0z1ac-yYZS5srx8jmDCHyJAuve0PvjUFLFoUJDw9bq0SZ_hUcJY-fSG3325NpE90NdLFEjNZNVG9tHWc85sluGqFo/s320/butt+joint.png" width="320" /></div>
<br />
Connection between the ends or edges of two parts making an angle to one another of 135-180° inclusive in the region of the joint.
<br />
<br />
<b>
<li>T Joint</li>
</b><br />
<div class="separator" style="clear: both; text-align: center;">
<img border="0" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFKXBnCUnlizAtCODBQPl8Ex1cym4EVmjjqwLRV7NHmWzg6Px0Y0_A3WJ-Y5q_sWOjjZiobNxoHn3Z4bZwUHD0Mcl-qg503OI6ZPub81QnSJdyWp2T25nadlS2RMXvoYnvItfzmNJejTQ/s320/T+joint.png" width="320" /></div>
<br />
Connection between the end or edge of one part and the face of the other part, the parts making an angle to one another of more than 5 up to and including 90° in the region of the joint.
<br />
<br />
<b>
<li>Corner Joint</li>
</b>
<br />
<div class="separator" style="clear: both; text-align: center;">
<img border="0" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrOVKcImW0FRoUWeRxgLLdGIlbr3eK9NuMTBsfm2vqLgLhzU3Xyetyzx38u_OrvzmzTODW4A_QEITjpWEOxKorKqz9d8nwKWbxoHl5_7niFGxAee9xxkvlRDkpBsHqKwQsKGgcssTUsHk/s320/Corner+Joint.png" width="320" /></div>
<br />
Connection between the ends or edges of two parts making an angle to one another of more than 30 but less than 135° in the region of the joint.
<br />
<br />
<b>
<li>Edge Joint</li>
</b><div class="separator" style="clear: both; text-align: center;">
<img border="0" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtj9pJ2dh9TR17etkspmuD3Oqu_IuTgSq6UkkUlnSRJxI68r3NfwhklP0cFveWi_NcEgODLPfejRCnpovW1SxPBGYKmM89oi1p6Yp_2CkkXthpnuAxGDMQto8spJyMuWHQqviKsfUHRWg/s320/edge+joint.png" width="320" /></div>
<br />
A connection between the edges of two parts making an angle to one another of 0-30° inclusive in the region of the joint.
<br />
<br />
<b>
<li>Cruciform Joint</li>
</b><div class="separator" style="clear: both; text-align: center;">
<br /></div>
<img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsbtMxA0eGUHi6eGA1i9BPRYkyTMmWj0bcCaF0Jk1rEXkxU5zbcoi87Fa9afOsA8yOkmKvh51cqyH5YjngtSjdQ29KVmUEIdZ3J-940TH1uzwg4EarAfD8E55XsB5wKXgTg9VbpMZbNH4/s320/cruciform.png" width="266" /><br />
<br />
A connection in which two flat plates or two bars are welded to another flat plate at right angles and on the same axis.
<br />
<br />
<b>
<li>Lap Joint</li>
</b><div class="separator" style="clear: both; text-align: center;">
<br /></div>
<img border="0" height="98" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLXsnisAXwU7BBcs5mhDnMzwcJvHvkbZMcU9F36ChuRCx0iUxfidLubB7SJbIklYeXoyVSw9ywgQQ1jKVNJjcQPy4ypuZ_94XphPfQZE3E8iHdbivh03iZrpIHrzpEKM1cmY0-GirKsnc/s320/Lap+Joint.png" width="320" /><br />
<br />
Connection between two overlapping parts making an angle to one another of 0-5° inclusive in the region of the weld or welds.
</ol>
belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com0tag:blogger.com,1999:blog-5462242472424491265.post-2766531283620862842016-05-16T01:29:00.000+07:002016-05-16T01:29:59.169+07:00Welding Position ( according to ISO 6947)<ol>
<b>
<li>Flat Position (PA).</li>
</b>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="margin-left: 1em; margin-right: 1em; text-align: center;">
<img border="0" height="100" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjl4AT1364xbTT81dVTEOU49Sg4FzwpEbK408kiQgQEwISVelyD8icSljs9AHT5Z0xmWFFNLPFQLACqhtCkVlOLP6iTr4qNDC64NOOOqXwxsnlN6-IIHmWzOPj6akVg1VAuRfJV120j9I/s320/flat+position.jpg" width="320" /></div>
<div class="separator" style="margin-left: 1em; margin-right: 1em; text-align: center;">
<br /></div>
Welding position in which the welding is horizontal with the centreline of the weld vertical.
<br />
<br />
<br />
<b>
<li>Horizontal-vertical Position (PB).</li>
</b><br />
<div class="separator" style="clear: both; text-align: center;">
<img border="0" height="194" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZW64_Lg29AHA55IqeAFMMhaNDldUg3ouONp47d0oHQ05r450NGxFkiumB5zLTsBHWx86XShnUVFgauqnETHtSTj0O8o06rnF9YocZwH7vKilFlkcULtYsRHpROh8s-hM286zBf4yqibk/s320/horizontal-vertical+position.jpg" width="320" /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div>
<br /></div>
<div>
Welding position in which the welding is horizontal (applicable in case of fillet welds).<br />
<br /></div>
<div>
<br /></div>
<b>
<li>Horizontal Position (PC).</li>
</b><br />
<div class="separator" style="clear: both; text-align: center;">
<img border="0" height="315" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOjWPEZZnwz9CZ9Xt3AAjSSBvQAimq68Mg_aO0A4-0x76LnJZjRdoa0r6pqtti_53RiSu3DWOw5Ri3WESnxlb1Ux7MfRcVDBw9quFRGoMlgHF5oLtJI4BMZUcwLn8vfpAN0hyPMqrS4Jo/s320/Horizontal+position.jpg" width="320" /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div>
Welding position in which the welding is horizontal, with the centreline of the weld horizontal.</div>
<div>
<br /></div>
<div>
<br /></div>
<b>
<li>Vertical-up Position (PF).</li>
</b>
<br />
<div class="separator" style="clear: both; text-align: center;">
<img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj81ubxVVGjJMSLeI4ElHHEy7lTd9eIbESk5q-ZDATYEnnD3mOhyXVPyEBH_jEn3tsZy1zfYZrwmQCqt875iSOM4xFTqXn_SUmwdRmohGqoHU5Bqz0izyh9kAZhyphenhyphenQtVkQr-dtnZOKUG7kU/s320/Vertical-up+position.jpg" width="311" /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div>
Welding position in which the welding is upwards.<br />
<br /></div>
<div>
<br /></div>
<b>
<li>Vertical-down Position (PG).</li>
</b>
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<img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZJPNRtUZFWonwZVRixR7VpTWBevCJAOSAlEjE5a51IQpwnMCtm-vFO5YQWv8Beyg745HnuezFjZ0xBlbdnqxT5fGl5XTzgIFAlGduRmyA-xHQNuTKPy9nwQ5Vv423WDtc9gV_n2GTB3M/s320/Vertical-down+position.jpg" width="314" /></div>
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Welding position in which the welding is downwards.<br />
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<li>Overhead Position (PE).</li>
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<img border="0" height="98" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzBRxSJsLKzE1MhV9QRntGNGaVp9HP7Akj2oNpdLdCYocrlNi8QRzElwZ1i-C0D3U3VF96tYrkMpgnIMokCT-zE3TbuHAtV2owd3AJYC6gIkO6C2yXdaCse3AjTBIV3jl_xTtd8-9odkI/s320/Overhead.jpg" width="320" /></div>
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A welding position in which the welding is horizontal and overhead (applicable in fillet welds).<br />
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<li>Horizontal-overhead Position (PD).</li>
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<img border="0" height="161" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEieksjnHrfoCliy4JHapFBpTpzMxrfT_GyFNnjfoOY6HxJ1sORXmVb_2mBsgm8tMN5_Fx3PddSUnv9MhFPyqfqf_vMwZ8jvumyia21VQWruTVB3_7USj1sZ5_yyKl8vtYMnx9iJqn0DPIE/s320/Horizontal-overhead+position.jpg" width="320" /></div>
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Welding position in which the welding is horizontal and overhead with the centreline of the weld vertical.<br />
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belajar koorhttp://www.blogger.com/profile/08948686711420678227noreply@blogger.com2