Pipe Distortion due to Weldolet Welding 2

[Delikado]

Any recommendation on how to practically repair/correct a banana-warped pipe due to weldolet welding?Heat treatment? and does anybody knows about allowable distortion mentioned in ASME or EN? I searched already but was not successful though. I would appreciate for any advice.

 

[metengr]

How big was the pipe and weld fitting and the material???

 

[MJCronin]

Is the run pipe thin walled (sched 10S) and/or large diameter ?

Welder experience and skills come to play here

The only time that I have heard of this problem is with thin-walled piping.

There is some help here:

http://www.eng-tips.com/viewthread.cfm?qid=369098

and here :

http://www.eng-tips.com/viewthread.cfm?qid=331515

MJCronin
Sr. Process Engineer

 

[Delikado]

Hello metengr and MJCronin,

The Pipe is NPS 20 and WT 9.53(Std) A671 Material.

 

[XL83NL]

This has happened to me in the past, as MJC referenced. No ASME nor EN reference found for that, came up with my own. From a practical point of view, what could help is to internally reinforce the pipe before welding with some bars (kind of like a barred tee)

 

[Delikado]

@XL83NL

Thanks for your input. So in that case what you did to the warped pipe? was it repaired?

Regards,
Delikado

Expecting life to be fair on you because you're a good person, is like expecting an angry bull not to charge on you because you're a vegetarian.

 

[XL83NL]

I think it wasd cut out and replaced.

 

[metengr]

Absolutely agree with XL83NL.

 

[pradipgoswami]

Hi Delikado,

Compared to a Set-in(through) or set-on nozzle, typical weldolet fittings on pipes involves more weld metal, hence resultant distortion. Use of strong-backs and balanced and sequential welding for at least 1/3 of the grove depth is always advisable. Major distortion is usually in the initial passes of the weld, hence at least 1/3 of the depth is recommended as rule of thumb. It may involve, more stops and starts, more grinding, frequent change of welding position, but essential. Pipe diameter, wall thickness,
fitting schedules, welding sequences, all should be considered before welding. Some interaction between the designer and welding engineer is essential.

As pointed out by the previous respondents pipes with major distortion/warping have to be replaced, heat correction would not be advisable. Minor localized distortion may be accepted, on case by case basis.

You may follow the following link for general guidance, rest is to be compensated by experiences.

Thanks.

https://app.aws.org/mwf/attachments/90/268590/ES-49BranchConnections.pdf

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[Delikado]

Hi Pradip, XL83NL

Thanks guys for all of your inputs, appreciate it a lot. We issued NCR to contractor and the pipe will be replaced. All in all it was a case of lack of supervision during welding, inexperience of the welder and pressure to finish the welds in a short time and to produce more. As always ended up spending more resources.

Regards,
Delikado

Expecting life to be fair on you because you're a good person, is like expecting an angry bull not to charge on you because you're a vegetarian.

 

[weldstan]

When welding the o'let to thin run pipe, I have always found that making the weld at the 3:00/9:00 position is best to mitigate distortion. It has spared many a pipe spool fabricator who had similar problems from further repairs.