PWHT for head or whole vessel
PWHT for head or whole vessel
(OP)
Dear forum member,
I have a vessel which the thickness for
sa516 gr70
shell ID 660.4mm: 18mmt
Torispherical head: 25mmt
After calculation, my dish head elongation is about 24% which (>5% need to be pwht). So i need to do pwht, my question is can i just heat treat the head(consider as stress relief) only or i need to do pwht the whole vessel after completion of fabrication?
I have a vessel which the thickness for
sa516 gr70
shell ID 660.4mm: 18mmt
Torispherical head: 25mmt
After calculation, my dish head elongation is about 24% which (>5% need to be pwht). So i need to do pwht, my question is can i just heat treat the head(consider as stress relief) only or i need to do pwht the whole vessel after completion of fabrication?





RE: PWHT for head or whole vessel
RE: PWHT for head or whole vessel
RE: PWHT for head or whole vessel
Dear vesselfab,i will prepare a plate which cut to a certain diameter as per advised by the head manufacturer, the manufacturer does not do hot forming for head, they just help us to forming/pressing and flanging the plate i provided into a dish head.Is it written in code that if there are hot forming performed during the manufacturing of the dish head can waived the requirement of pwht for head? Do you mind point me out which code in asme section 8 shows it?
Dear metengr, thanks for your reply, after calculation, the vessel does not need to be completely pwht, just the head fiber elongation value are exceeded the pwht exempted value and is not entitled of the exemption of UCS-79 because of the UCS-79(d)(3) thickness > 16mmt
RE: PWHT for head or whole vessel
RE: PWHT for head or whole vessel
UCS-79(d) shows that all cold forming pressure parts requires heat treatment, i didn't see any statement stating that hot forming a head could waive the heat treatment process. Can you enlighten me? Thanks.
RE: PWHT for head or whole vessel
It does not mention that hot formed parts need heat treatment.
This is why most head manufactures do a lot of hot forming.
RE: PWHT for head or whole vessel
RE: PWHT for head or whole vessel
Thanks so much for your explaination