nozzle-head PWHT

[Vessel-SA]

Hi everyone,
I am designing a pressure vessel per ASME SEC VIII-1, there is a hillside (offset) nozzle on a head with a nominal thickness of 1.5". (SA-516 70). The vessel itself does not require PWHT. Per UG-40(f)(5)(d) states "in Figures UW-16.1 and UW-16.2, the thickness of the weld across the nozzle neck or shell or head or reinforcing pad or attachment fillet weld, whichever is the greater" is the nominal thickness to determine whether PWHT is required or not. Trying to figure out if the nozzle to head requires a local PWHT or not. In this case, the thickness of the groove weld across the nozzle neck is 2.042" (because it is hillside). COMPRESS considers the thickness of the full penetration weld across the head to equal the head thickness for the nozzle PWHT check, so it does not mark as the PWHT is required. However, if the actual thickness of the weld (groove weld depth) to be considered then the PWHT must be performed. What is your thoughts/ interpretation on this?

Regards,

 

[r6155]

Best is a drawing.

 

[Vessel-SA]

Best is a drawing.

A drawing of what? I think I described everything needed. Please let me know if there's anything missing that you need to know to share your thoughts.

 

[r6155]

Drawing, sketch, hand drawing, etc. of the nozzle with complete dimensions of welding details (neck, reinforcement pad, head type, etc.).
"Good drawing, and less words".

 

[David3399]

UW-40 Is telling you that you need to take into account either the thickness of the nozzle (set on), thickness of the shell or head (set thru), thickness of the repad (if applicable), thickness of the fillet welds (throat dimension). The greatest thickness being the governing thickness.
In your case it must be the head thickness of 1.5".

You also must preheat to 200F to eliminate the requirement for PWHT.

 

[r6155]

Vessel-SA said​

"thickness of the groove weld across the nozzle neck is 2.042" (because it is hillside)"

PWHT is required.

 

[Vessel-SA]

UW-40 Is telling you that you need to take into account either the thickness of the nozzle (set on), thickness of the shell or head (set thru), thickness of the repad (if applicable), thickness of the fillet welds (throat dimension). The greatest thickness being the governing thickness.
In your case it must be the head thickness of 1.5".

You also must preheat to 200F to eliminate the requirement for PWHT.

Yeah, that's what I was referring to in my original post (though there was a typo — I meant UW-40(f)(5)(d)). but the question is whether 1.5" or 2.042" shall be considered as the governing thickness for PWHT

 

[Vessel-SA]

Vessel-SA said​

"thickness of the groove weld across the nozzle neck is 2.042" (because it is hillside)"

PWHT is required.

but COMPRESS does not agree with 2.042" as the governing thickness and it uses 1.5" (the nominal head thickness) for PWHT check

 

[r6155]

I'll stop until I receive your sketch.

 

[Vessel-SA]

I'll stop until I receive your sketch.

Thank you,

 

[jt1234]

Thickness is considered "normal" to the surface, not measured in the hill side length, so you don't need local PWHT. Correct me if I am wrong. We have so many hill-sided nozzles in all kinds of projects, never have any one need local PWHT. Also the so called "local PWHT" is to wrap entire shell or head around for a uniform thermal growth, not a "local" heated up to 1100F in the nozzle junction, that can burst the area.

 

[r6155]

The (OP) didn't mention the overall dimensions. Just words, lots of words. More words can lead to more errors. Like he said UG-40 instead of UW-40.
I insist: It's better if the (OP) sends us a drawing of the nozzle, I'm sure I can find errors in the drawing.

 

[Vessel-SA]

The (OP) didn't mention the overall dimensions. Just words, lots of words. More words can lead to more errors. Like he said UG-40 instead of UW-40.
I insist: It's better if the (OP) sends us a drawing of the nozzle, I'm sure I can find errors in the drawing.

I sent the model to COMPRESS support and asked the same question. They agree that the weld thickness is greater than 1.5", but they use the nominal thickness of the head for the weld across the nozzle neck. Below is part of their response:

appreciate your patience while I have been discussing this inquiry further with some of the other Engineers and Program Developers here at Codeware. As you mentioned, Paragraph UW-40(f)(5)(-d) states, “in Figures UW-16.1 and UW-16.2, the thickness of the weld across the nozzle neck or shell or head or reinforcing pad or attachment fillet weld, whichever is greater.”

In the provided file, the nozzle is a set in (implant) nozzle with full penetration groove welds through the head, which has a 1.5” thickness. COMPRESS considers the thickness of the full penetration weld across the head to be equal to the head thickness of 1.5" for the PWHT check.

Codeware does not strive to place its own interpretation on Code rules, we try to follow the Code as it is written. In situations such as this, the Code is not entirely clear and COMPRESS applies the rules using Codeware’s understanding of the Code's intent.

With that being said, if you do not agree with the approach taken by COMPRESS, I suggest reaching out to ASME for an official Code interpretation. If you do submit for an interpretation, and they reply, please let us know.

I know you're trying to help, and I appreciate it. Unfortunately, I’m currently on vacation and will be back at work in two weeks. Once I return, I can create a drawing and upload it here if you still think it’s needed.