Head is required PWHT? 1

[John121]

Vessel shell Thickness is 150mm
Head is hemispherical and thickness is 90mm.
Head fiber elongation is less than 5%.

My question is whether Head is required PWHT?
shell plate thickness is 150mm , Vendor has selected PWHT cycle time and temp as per UCS 56.But he has not specified for Head.
Incase PWHT is required for head then Head PWHT Cycle and time is same as Shell plate or It should be according to thickness 90mm.

 

[SnTMan]

Akadu, you should spend some time reading whatever Code of construction (ASME VIII 1 perhaps?) is applicable to your class of work. If you are PWHT'ing a welded assembly, in other words shell to head assembly there will be specific rules governing the thickness of interest / PWHT time.

(HINT UW-40)

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[John121]

Mr.Mike Thanks for reply. I already read ASME before posting but it was not clear to me.

As per UW -40 17-f, Nominal thickness interpret as Highest for PWHT consideration. See below two clause.

(f) The term nominal thickness as used in Tables
UCS-56-1 through UCS-56-11, UCS-56.1, UHA-32-1
through UHA-32-7,andUHT-56,is the thickness of the
welded joint as defined below. For pressure vessels or
parts of pressure vessels being postweld heat treated in
a furnace charge, it is the greatest weld thickness for all
weld type s as defined in (1) through (6) below in any vessel or vessel part that has not previously been post weld heat treated.

As per UW -40 17-f (5)-a, Nominal thickness interpret for shell to head joint interpret as thinner of head and shell.
(5)When a welded joint connects parts of unequal
thicknesses, the nominal thickness shall be the following:
(-a) the thinner of two adjacent butt‐welded parts including head to shell connections

Vendor specify Hold Time as per Shell plate although head is thinner.

 

[weldstan]

Both thicknesses require PWHT. Your vendor (vessel Manufacturer assumed) will PWHT the vessel in a furnace and the hold time will be per the shell thickness. This is common manufacturing process.

 

Head is required PWHT?

What does that mean?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Compositepro]

Eng-tips has an international audience. We must be tolerant of posts by people whose main language is not English. His meaning was clarified in his question.

 

I read some pretty fractured prose by people whose main language IS English.
Where I work I could have a pretty lucrative sideline teaching remedial English to adult engineers educated in Canada.

We're now officially off-topic so this will be my last word.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[John121]

Thanks to all. its understand that PWHT hold time and temp based on shell thickness.

 

[Mateeng]

Hi John121,
The head itself no need any stress Relief heat treatment after forming because the fiber elongation is less than 5%. However the shell to head weld shall be subjected to to PWHT based on the shell thickness assigned soaking time in UCS-56. The reason for soaking time base on shell thickness because of shell longitudinal weld to be stress reified too. The shell thickness is the governing thickness.

 

[0707]

Yes according to ASME PWHT will be required.

luis