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04:42 Feb-09-2010

Carlos

R & D, - -
UCV & EGROUP,
Venezuela,
Joined Oct 2008
120
DEFECTS IN MANUAL WELD STATISTICS

Hello NDT friends.

Does anyone have some link to find a Girth Weld Defects Statistics (number of repaired welds vs. total number of welds) with manual SMAW and GMAW???.
I have found a paper in Welding Journal but focused in Mechanized Field-Welded Pipelines (Wagner and Patchett).

Thank you!!!

 
22:54 Feb-09-2010

Roger Duwe

NDT Inspector, API-510, 570, 653
MISTRAS,
USA,
Joined Jan 2009
148
Re: DEFECTS IN MANUAL WELD STATISTICS In Reply to Carlos at 04:42 Feb-09-2010 (Opening).

Carlos, I was told about 25-30 years ago that a 6-percent reject/repair rate is the upper limit of the norm for SMAW. Anything substantially greater than that is cause for investigation. My experience agrees with that number. GMAW inspected visually VT and radiographically RT should have a little lower reject rate, and ultrasonic UT inspection should give a little higher reject rate than 6 percent [small areas of Lack-of-Fusion]. Pulsed GMAW should have a very low reject rate on everything but the root. If the root is "looked in" by another welder by viewing from the far side of the open root, I am used to seeing a 1-2 percent reject rate.

In the USA, cross-country underground pipelines are typically welded by better-than-average welders, and that reject rate runs about 1-2 percent.

The main item in reject rates is the quality of the welders. With hand-picked welders, it is common to have an entire [small or medium] project with zero rejects.

 
03:20 Feb-10-2010

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
278
Re: DEFECTS IN MANUAL WELD STATISTICS In Reply to Carlos at 04:42 Feb-09-2010 (Opening).

Good question last year we were researching the same topic and could find little published material. Talking to numerous industry people it seemed 5% was considered the upper limit that people felt was acceptable but that was general. It depends upon application for example we found instances of high quality fatigue sensitive welds with 20% or higher and repairs not permitted.
Some contrcators will quote 2-3% for workmanship criteria increasing to 6-8% for tight ECA based criteria.

 
20:25 Feb-10-2010

Manuel Haces

Director, - Wire rope inspection
Haces Inspección del Noreste and Wire Rope Inspection,
Mexico,
Joined Jun 2002
119
Re: DEFECTS IN MANUAL WELD STATISTICS In Reply to Carlos at 04:42 Feb-09-2010 (Opening).

Very good answers, and what we do for quotation of NDT in any jobs, we expect to have as much as 10% in cost regarding repairs of welds and hence re-inspect.

 


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