Temperature of solution annealing lower than 3.1 certificate

[ElCidCampeador]

Hello,

I've just received from a workshop all documentation regarding to 2 hemisphers hot formed from a plate, material 316L.
This 2 hemisphere will be welded each other in order to become a pressure vessel (a sphere).

In 3.1 MTR of starting plate, solution annealed was performed @ 1070°C.

After hot forming, my client wanted a PFHT (even if not required by ASME for % strain and design temperature assigned).

In PFHT certificate of supplier I've found that temperature of solution annealing after forming was 1060°C.

From my old memories I knew that it's common practice to do PFHT @ temperature HIGHER than starting material's one: is it right?
Does ASME CODE require something like that?

Are these 2 hemisphere acceptable or do I have to do another PFHT @ temperature HIGHER than 1070°C?

Thank you

 

[weldstan]

There is no such requirement in ASME VIII and the solution anneal was appropriately solution annealed.

 

[The Obturator]

If your purchase order specification stated a specific requirement, then the corresponding supply should be the same, unless the vendor pointed out a discrepancy on order receipt. If the temperature is different, then it is a non conformance. Whether the requirement is in ASME or not is immaterial (though can be used in argument earlier on before manufacture).

Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[ElCidCampeador]

If your purchase order specification stated a specific requirement, then the corresponding supply should be the same, unless the vendor pointed out a discrepancy on order receipt. If the temperature is different, then it is a non conformance. Whether the requirement is in ASME or not is immaterial (though can be used in argument earlier on before manufacture).

mmm it's not so easy.

Both heat treatment of steel mill and forming head supplier are usually @ fixed temperature: if you are a small company (as in my case) you can't go to the steelmaker and say "Hey, change heat treatment temperature please".
For head forming supplier (which in my case will do also PFHT as all-in-one after forming), the problem is similar because the supplier, in order to save money, collect all heads it is working on and do 1 heat treatment for all this items together. You can pay to change HT temperature (supplier will do a dedicated HT only for your heads), of course in this case you can, but it will cost extra-money (that I don't have).

 

[The Obturator]

I understand your vendors modus operandi, BUT the vendor has an obligation to inform you upfront of your requirement can be met or not. If he would have done that in the first place, at least you can then approach your own client with the deviation for acceptance. Its little things like this that are ignored/overlooked in the pursuit of an order that come back to bite you later. Personally, If my paperwork/contract asked for it and it was accepted by the vendor without exception, then I'd reject the supply. Get the vendor to correct it to spec or provide reasons for acceptance with you can maybe agree with your client. This is a contractual agreement. If you missed off the requirement, then I'm afraid the onus is on you to get acceptance from your client.

Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[weldstan]

Whatever solotion anneal was done by the steel mill was undone by the hot forming operation. The only solution treatment that is truly valid is that performed after hot forming.

 

[EdStainless]

1060C is still an acceptable anneal temp fro this alloy.
I would be glad that hey did it because then you are not at the mercy of their hot working conditions.
It would be nice if they had used the same temp, but given the tolerance on this I wouldn't be concerned.

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P.E. Metallurgy, consulting work welcomed