Weld Fit-Up Inspection Employee Training [PDF]

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Employee Training



Weld Fit-Up Verification steps to success



Just leave the gap at ¼”. The welder will be able to weld across that!



Let’s see… the WPS calls for a 1/8” MAX gap!



This is a Required ASME Code Verification



Is this what we call teamwork?



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Employee Training Weld Fit-Up Verification



Good fit up of the joint is crucial for high quality welding. Poor fit up can make it difficult for the welder to fuse both sides of the weld root. An unfused root can be a stress riser for fatigue cracking and/or a site for deposit formation and corrosion. Large diameter vessel shells, pipe and fittings are often out of round and require adjustment during fit-up. Joint alignment can be done with mechanical devices and should be free of depressions, hammer marks, and arc strikes. Heat is not used in the alignment of joints where it has been determined that the corrosion resistance of the alloy is reduced. Misalignment tolerances are specified as a percentage of the wall thicknesses involved, and determined by the service requirements.



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Employee Training Weld Fit-Up Verification



Definitions



Backing



A material or device placed against the back-side of the joint to support and retain molten weld metal.



Base metal



The metal to be welded.



Bevel angle



The angle on one side or surface of the member.



Groove angle



The total included angle of the groove that makes up the weld joint.



Crack



A fracture in the weld or base metal.



Complete penetration



When the weld metal or tack weld metal extends through to the bottom of the weld joint.



Filler metal



The metal or alloy to be added in making a welded joint.



Lack of fusion



A non-standard term indicating a weld defect in which fusion did not occur between weld metal and fusion faces or adjoining weld beads.



Overlap:



The protrusion of unfused weld metal beyond the weld toe or weld root.



Root face



The portion of the groove face within the weld joint on the underside of the weld.



Root gap



A separation or gap at the joint root between the work pieces.



Subweldement



An incomplete vessel, or part, that is joined by welding



t



The thickness of the thinner material or part being joined.



Tack weld



A weld made to hold the parts of a weldment in proper alignment until the final welds are made. 3



Employee Training Weld Fit-Up Verification



Tasks of Fit-Up Verification ● Material ID Traceability Verification ● Welder Qualification Verification ● Weld Joint Preparation Check ● Weld Joint Fit-Up Verification ★ Alignment Check ★ Dimensional Check ★ Orientation Check ● Tack Weld Condition Analysis ● Documentation Completion 4



Employee Training Weld Fit-Up Verification



Material ID Traceability Verification ● Material Specification and Grade ● Heat No. / Plate No. ● Part No. Identification



● Documentation Completion 5



Employee Training Weld Fit-Up Verification



Welder Qualification Verification ● Welder is currently qualified ★ Welding Process Qualification ★ Base Metal Qualification ★ Filler Metal Qualification ★ Welding Position Qualification



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Employee Training Weld Fit-Up Verification



Weld Joint Preparation Check ● Bevel Correct, when required



● Joint Surface Cleanliness ★ No oil, grease, other contaminates ★ No rips or breakouts of base metal



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Employee Training Weld Fit-Up Verification



Weld Joint Fit-Up Verification ● Alignment Check ★ Tolerance is ¼t or 1/8”, whichever is less ● Backing Check for weld joints with backing ★ Tolerance is 1/16” maximum gap at backing band ● Dimensional Check using drawing ★ within drawing tolerance ● Orientation Check using drawing ★ within drawing tolerance 8



Employee Training Weld Fit-Up Verification



Tack Weld Condition Verification ● Full Weld Joint Penetration



● Tack Welds must: ★ be feathered into the weld joint at ends to allow good weld penetration into tack ★ have no cracks ★ have complete fusion ★ have no overlap or tunnels 9



Employee Training Weld Fit-Up Verification



Documentation Completion ● Head Fit-Up Documentation ★ Liquid Container Head Log ★ Documentation on Head subweldment



● Girth Fit-Up Documentation ★ Container Assembly Verification ★ Special Container Assembly ★ Documentation on Vessel Shell subweldment



● Drain and Vent Nozzle Fit-Up Documentation ★ Documentation on Vessel Shell subweldment



● Piping Fit-Up Documentation ★ B 31.3 Piping Verification Record For Tanks ★ Piping Verification Sheet 10