Hello Friends, I have some doubt ab

[John121]

About PWHT and after hydrotest welding
Hello Friends, I have some doubt about ASME Div 2 clause interpretation) for following issue facing one of my task. Due to some issue, We need to weld non-pressure(piping/platform cleats) after PWHT but before Hydrotest. Any one can confirm my understanding is correct?

1. Does ASME Sec VIII, Div.2 permit welding of 20 mm thick cleats (with weld size 12.6mm) directly onto 140 mm thick shell that has already been PWHT but before final Hydrostatic test?
(My interpretation, 1.Yes , Para. 4.2.5.6 (e) and Para. 6.11 Tables, Table 6.8 (a) (3) of ASME Sec.VIII Div.2)

2. Is there any requirement in ASME Sec VIII Div 2, that requires PWHT for sour / H2S service regardless of weld joint thickness?
(MY Interpretation, There is no such requirement in ASME Sec.VIII Div.2.)

3. If a reinforcement (RF) Pad is welded to the vessel shell and all subjected to PWHT, can cleats be welded to the RF Pad at a later date without the need for further PWHT (regardless of RF Pad thickness)?
(My interpretation, Yes Since the welding onto the pad is beyond the ASME code boundary.(Para. 1.2.3 (b) of ASME Sec.VIII Div.2)

4. Can the welding of the cleat onto the RF Pad (regardless of RF thickness) be done even after vessel Hydrotest?

(My interpretation, Yes Same as above no.3.)

 

[Some Curious Guy]

I assume that the material is CS and the non pressure part cleat to shell weld does not require PWHT
1) Agree.
2) Agree.
3) Agree. However even though the cleat is outside the geometric scope of the code it still must meet all requirements of fabrication, welding, heat treatment per good engineering practices.

Your real task here is not to convince your AI or yourself about the legal scope of the code. Most client prohibit any welding after PWHT regardless of what the code says.

The cleat you are planning to weld after PWHT or maybe after hydrotest can be treated as a Site weld.

You can find many literature on the internet and even in NBC site where an improper site weld without proper precautions resulted local hardended zone and point of failure. Speak to your Client / Owner of the vessel on how they approach site welds.

 

[mskds545]

ASME VIII-2 does not generally have requirements for specific environmental cracking and corrosion issues. You formal responsibilities depend on whether you are the specifier, manufacturer or owner, as well as the specifics of your contract. Regardless, it's important that the vessel is fit for its purpose. For technical guidance, you'll do well to review API and NACE guidelines.

As for the attachment, I'd use a pad. It's a much cleaner approach and will save you a lot of argument.

-mskds545

 

[John121]

mskds545 (Mechanical)
Thank you but we can use pad due to obstruction in rolling operation at vendor shop. This was our first choice.