UW-2(c) ERW Question

[Afox88]

Hi,

I am working on a shell and tube design for ASME VIII-1, and my unfired steam boiler falls under UW-2(c). Specifically, my question is with the first part of UW-2(c)(2) which I transcribed below:

UW-2(c)(2): All butt welded joints shall be fully radiographed except under the provisions of UW-11(a)(4) and except for ERW pipe weld seams.

My customer requires SS304 and I was planning on using welded SA-312 SS304 pipe. My AI is under the impression that SA-312 is not ERW but just a normal butt weld. Although I disagreed with him, I did not have a reason to argue before today. Basically, I want to know if the long seam is considered ERW and if I am required to x-ray the long seam of the shell and nozzles in order to comply. Please put some reference that I can show my inspector.

 

[aburafdi]

Afox88,

I try to show you some points:
1. SA-312, par 1.1 says "straight-seam welded".
2. SA-312 par 6.1.3 says "welded pipe shall be made using an automatic welding process with no addition of filler metal"
3. UW-2(c)(2) says "the ERW weld shall completed using high frequency welding (HFI)"..... But also limitation for this ERW pipe: the thickness max 0.5" and diameter max 24".

IMO as long as you can show to your Inspector that you comply to all of those requirements, it's should be OK (no need RT).
However, -I assume you buy the pipe- the pipe manufacturer still need to do ET or hydrostatic test as part of the requirement of SA-312.

Regards,
AR

 

[Afox88]

AR,

Thanks for the quick reply. I noticed these sections as well, but I can only comply with your third point if SA-312 is made using a high frequency weld. I am not familiar enough with the weld of SA-312 pipe to be sure that it complies.

Your assumption is correct that all pipe we purchase is manufactured to the requirements of SA-312 and the tests required.

 

[aburafdi]

When the pipe manufacturer states in their MTR saying that the pipe is welded, then it means the welding is by HFI: this process is automatic and no filler metal is used (as required by SA-312).

 

[Afox88]

Perfect, thank you for your help.

 

[GenB]

The MTR specifically shall mention the type of welding as apply to the specification as HFI ERW FW SAW other

 

[weldstan]

GTAW process without filler metal additions are also used. Confirm process with the manufacturer.