Weld joint Repair

[Saidur Rahman]

Dear Experts,

I am working on 30" High pressure gas transmission pipeline project. Today i found that in one RT film there was 100 mm Internal undercut. After repair RT film shows that again 45 mm internal undercut with Internal Concavity. But my superior says that only one time repair is acceptable & joint should go for cut-out  because if again repair then Susceptible micro structure will form. my question is How many times repair is acceptable? Pipe material API 5L-X 60. thickness= 14.3 mm

and also for Process piping how many times repair is acceptable if PWHT is a service requirement?

Regards,

Md. Saidur Rahman

QA/QC

GTCL

[Faisal Shahzad Meer]

Dear

 

Regarding Pipeline as per Saudi Aramco standard Two time repair is allowed even for grade 70 materials ,third time we have to go for CUT out. I think there is nothing specific in the code regarding attempts of repair only customer specification may dictate this issue.

 

Regards

 

Faisal Shahzad Meer

Project Quality Supervisor-Welding

J-505, Saudi Aramco Wasit Downstream Pipelines Project

 

TEL :+966 3 6795805-7 Ext. 124|www.gccksa.com

E-mail  fm...@gccksa.com 

+966 - 553919249

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[SANTOSH K]

Hi Saidur,

There is no mandatory requirement for no of times welding at same in any code joint/location. Normally we may allow 3 times re welding for any repair as a standard practice as long as the welder controls heat input. High hardness will be impact on  various factors like type service, temperature, damaged mechanism.

You can carried out hardness test & can allow welding if the hardness values are with in the limit. It would be better if you have any repair welding procedure.

Regards,

Santosh.

[guru vasanth]

How many times can a weld be re-welded?

Frequently Asked Questions

However, much will depend on the type of material being welded and the process in use. If the material is known to be metallurgically 'sensitive' to heat input, which could result in degradation of both the HAZ and weld deposit, it then becomes a question of complete removal of the welded joint and replacement with an inserted section.

Materials such as mild, low carbon and carbon-manganese steels, are considered to be very tolerant to heat input and may accept at least two or more re-weld operations. In the case of low alloy steels, re-welds will be governed by the heat-treated condition in which they were supplied. For the Cr-Mo steels, up to two re-welds may be carried out, but consideration needs to be given to the post-weld heat treatment operations and possible resultant degradation of the welded joint.

With the 3xx series stainless steels, two re-welds may be tolerated, but in the case of the duplex and super duplex stainless steels, only one re-weld operation is advisable, and then with extreme care and control over the heat input. Ideally, for these complex metallurgical materials, avoidance of any form of re-weld operation is favoured.

The aluminium alloys (5xxx) series can generally be regarded as a two re-weld operation but the (6xxx) series is far more sensitive to heat input and even a single re-weld operation is undesirable.

Of course when considering re-weld operations for what ever reason, consideration must be given to the following: material thickness, distortion problems, build up of residual stresses, and not forgetting the weldability rating of the material.

Thanks and regards

Guru

[jiji lal]

Dear Saidur,

for mainline welding API 5L-X 60 series pipe with thickness up to 15 mm,weld repair is allowed for max. two times prior to take cut out decision. Any how it be given in welding . spec. or in work procedure for production / repair welding procedures. 

regards

jijilal k m

[indh...@yahoo.co.in]

I think you should verify the requirements in specification too Sent from Yahoo Mail on Android

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From: guru vasanth <guruv...@gmail.com>;
To: <material...@googlegroups.com>;
Subject: Re: [MW:20453] Weld joint Repair
Sent: Tue, Apr 1, 2014 4:19:00 AM

[mahammed javeed]

Dear,

 

Regards to your query, It is not advisable to repair the weld joint more than twice, as it could impact the micro structure of the HAZ and the base metal. The standard has not put any restrictions on the number of times can a joint be repaired, but usually clients doesn't allow more then two times. It is up to the client discretion and project specification, but no reference you find the code. The code says the joint shall be repaired by using the qualified procedure/ same procedure and tested by the same method as used initially for the joint.

 

Thanks

M. Javeed

Quality Supervisor- Welding.