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Up Topic Welding Industry / General Welding Discussion / Rewelding of RT Rejected Joints
- - By mcarucci Date 04-06-2001 13:04
Do any guidelines exist for determining the number of times a pipe or tube joint can be cut out and rewelded? In a specific instance I have a 6" sched. 40 304 ss pipe joint that has been rejected for lop. It has been cut out and rewelded twice and has failed RT again for the same reason. The line will see a woking temp. of 350*F and 600' PSI in service.
Parent - By pipewelder_1999 (****) Date 04-11-2001 20:06
As far as the requirements of ASME sec I go there is no stated limit I am aware of. That does not however preclude the need to look closely at the service conditions and make an engineering decision based on the effects from multiple heating cyles for the material and wether this could affect corrosion or fatigue properties.

The NBIC code requires "Repair Procedures" but the last edition I looked at didn't restrict the number of repairs. Maybe someone working with a current NBIC could comment.


Gerald Austin
http://www.geocities.com/pipewelder_1999/
Parent - By M EL-SABSABI Date 04-16-2001 13:37

i think you can repaire it for three times (its legend)if it fails after that
its up to the inspecter (welding) to decide what to do.
Parent - - By G.S.Crisi (****) Date 04-16-2001 22:47
Back in my days of erector engineer they said that three repairs were the maximum. Where did this number come from? As Mr. El Sabsabi says, it was a legend (or a magic number someone pulled off the air). I'd say that Pipewelder is correct: you should use your good engineering judgement and make a sound decision.
By the way, have you taken a look at the ANSI/ASME B 31.3 Code? B 31.3 is the one that governs Petroleum Refinery and Chemical plant piping.
What's the NBIC Code?
Giovanni S. Crisi
Sao Paulo - Brazil
Parent - - By M EL-SABSABI Date 04-17-2001 13:16
that number did not come frome air we have to look closely at the mater .being a certifeid welding inspecter & welding superviser to both pressure equipment & structural when i face a problem like that i,ve to
make a decesion ,you must look at, joint, repaire lokation ,the defect size ,acssesability ,to deside to repaire 1,or,2,to,3 times max to comply with the relavent standard if you using ASME OR INTERNATIONAL ONE OR ,,,,? NOW IF THER IS A PROBLEM FROM THE WELDER I HAVE TO RE-QUALIFY HIM OR RE-PLACE HIM
i hope i made it clear to you mr GIOVANNI,,,,,,,,,,.

M EL-SABSABI
SYDNEY AUSTRALIA.
Parent - By RonG (****) Date 04-17-2001 16:15
I differ with you on failure beyound 3 times sir. I can tell you of a great many items in service that get cut away and rewelded every three years for the past 30 that I have been doing it. I belive that is why we have procedures to show it can be done. The items I refer to see some very heay stress of all types.
Parent - By G.S.Crisi (****) Date 04-18-2001 00:37
Dear Mr. El-Sabsabi,
I think we're saying the same thing with different words. When I said that the quantity of times that a joint can be repaired is 3, and that that is a "magic number", I intended to say that, before deciding how many repairs you can make, you should carry out a careful study on the matter based on a series of considerations (most of which you list in your answer), and then, using your good engineering judgement, take a decision. You might decide that only one repair is possible, or you can decide, as Ron says in his answer, that many are possible.
What did you intend to mean by saying "legend"? Is not the same as "magic number" in a different expression?
Best regards
Giovanni S. Crisi
Parent - By mcarucci Date 04-17-2001 13:28
B31.3, Sect. 127 addresses weld repairs but doesn't mention any limits for repairs. The NBIC is the National Board Inspection Code.
Parent - - By mcoffee Date 04-17-2001 20:07
Repairs are based off the magnitude of the defect compared to cost impact. Since the material is stainless, weld distortion becomes an issue as well as the joint becoming brittle, corrision effectiveness can be impacted. I"m familure with about every Code and was a ASME Authorized Inspector currently I work to ASME, Ashraie, D.1.1, 3A, API and numerious forign Codes and know of no set guidelines. Use good quality judgment.
Parent - By bspeirs (*) Date 04-18-2001 02:31
Just working off my limited memory, but I recall a pipeline code mentioning maximum number of repairs - possibly the API standard for pipeline welding (1104?)
Parent - By Dirk (*) Date 04-18-2001 02:56
The limit for the number of attempts at a repair is generally (not all alloys are forgiving) one of ecomomics and the fact that the more attempts made the less desireable the repair joint configuration becomes.

The 3 strikes and out is a rule of thumb used by many in many different fabrication stuations but there is always an exception to every rule.

Regards

Dirk
Up Topic Welding Industry / General Welding Discussion / Rewelding of RT Rejected Joints

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