Heat Treated Heads

[JBW76]

I'm building a vessel and the heads were "Cold Formed" -- the vendor has heat treated them and shipped them to me.
These heads are to have Nozzles welded into them and then (obviously) they will be welded onto the vessel Cylinder.

Am I required to Heat Treat The heads again after they have had the Pipe and Flanges welded into them?

Or am I required to wait and Heat treat the entire vessel because of this, or do I have to heat treat at all?


Thanks in advance

 

[IQM]

JBW76 would tell us what heat treatment process was done to the heads? Do you need to do a PWHT after the vessel is completed?

 

[metengr]

Is this a Section VIII pressure vessel? If so, please read the code.

What is the material of the heads and thickness?

 

[Mech2325]

Please clarify the "Heat treatment". Heat treatment can be "Normalizing" or it can be that vendor procured a normalized plate (which they generally do) and then "stress relieved" due to EFE exceeding 5%. Now,if the head has been stress relieved and then there comes a PWHT requirement, then PWHT needs to be done. Yhis depends upon the vendor he opts for a localized PWHT or not.Remember, PWHT is thr heat treatment that is done after welding.

 

[JBW76]

IT is a section VIII vessel - and the vessel was not required to be Heat treated as a "service requirement"

The vendor heat treated the heads after forming them is all I know - I don't have his process, or his temp/hold times.
They were baked out after being formed is all I know at this point

 

[Mech2325]

Heat treatment (PWHT) requirement, if it comes, will have to be done, now it depends whether vendor does localized PWHT or of the entire vessel.

 

[metengr]

Not good enough. You will need to confirm from the vendor what was exactly done to ensure compliance with ASME B&PV Code. This should have been part of the paperwork trail when you received the heads. Again, you should read the code!

 

[JBW76]

Thank you, I have requested from the Head vendor all documentation, and will bury myself in the ASME code book reading.

I will also buy Hot formed heads next time.

 

[Don56]

Hot formed heads are not the solution to all evils. Knowledge is the solution. We need more of it to help you. What material are the heads made from. Why were they heat treated? Stress relieved per UG-79? Normalized? Quench and Tempered?

 

[JBW76]

The heads are SA-516-70 and they were exceeding the EFE fiber elongation 5% -- The purchasing manager took it upon himself to get cold formed heads with the requirement that the vendor stress relieve.
I don't have the paperwork on the vendors stress relief procedure yet, but I will. The vendor is very reputable and I'm certain the heads comply to the B&PV code.

It is a small vessel (7 feet x 36" od)

 

[metengr]

JBW76
Does your shop have an ASME U-Stamp Authorization?

 

[david339933]

Your purchasing manager is not wrong in getting cold formed heads and having them heat treated. This happens all the time. The problem however is that you state that this is a reputable vendor, and yet they didn't provide a heat chart?....sketchy.

 

[david339933]

In addition, if you didn't need PWHT for the vessel, then having heads heat treated doesn't change that fact. Get the chart, confirm temp/time at temp, weld in your nozzles, weld the circ seam and be done with it. No PWHT required.

 

[JBW76]

'david339933' -- thanks for the help. My vendor sent the proper documentation, I just haven't gotten them in front of me.

I think most people believe that if the heads are heat treated, then you cannot weld or burn on them without heat treating them again.
And if you can, then it's because of an exemption somewhere that spells it out.

So, you just work under the assumption that because PWHT wasn't a service requirement from my client - then I don't have to heat treat the whole vessel because the heads happened to
get a heat treat off-site

 

[Mech2325]

What is the thickness of head?? PWHT requirement comes if the thickness is greater than 32mm or if preheating is done then can be exempted from 32-38mm. See UCS 56

 

[JBW76]

The head is 5/8" thick. (Nom.)

 

[JBW76]

Is this what UCS-56 (e)& (f) is telling me regarding "WELD REPAIRS"

Is a "WELD REPAIR" considered to be the act of welding/adding nozzles and a skirt cylinder to the 2:1 elliptical head?

 

[Mech2325]

There shouldn't be any requirement of PWHT for this head