Why specify PWHT on Studding Outlet based solely on the thickness?

[lcarter157]

I am welding a 2" 300# Studding outlet (Normalized) on an existing vessel. The vessel shell material is SA 516-70 Normalized, 1.25" thick, but not PWHT as it is not in severe service. The Studding outlet wall is 2.25" thick and it is "Set on" with a 7/8" fillet weld on the inside and 1/2" fillet weld on the outside.

PVElite says that due to the geometry, the nozzle must be PWHT, I specified that the vessel shell was not PWHT. The client does not want to do PWHT on at 144" Dia. vessel. My explanation was that PWHT was specified solely on the Studding wall thickness and not weld size. I proposed Method 1. Higher preheat temperature as an Alternate to PWHT per NBIC R-1000. He still questions why PWHT was even specified since we are also welding other nozzles "set-in" with full 1.25" groove welds.

Can anyone shed any light on this PWHT requirement based on geometry?

 

[SnTMan]

lcarter157, I am not 100% convinced that PVE handles this correctly, but you might see if you get a choice of attachment detail as per Fig UW-16.1. Changing (if possible) from a full-pen detail to a set-on may remove the flag.

In any case, PWHT requirements are generally based on the weld thickness, not necessarily the member thickness, see UW-40(f).

Regards,

Mike

 

[bernoullies123]

UW-40(f) refers to nonpressure parts.

 

[bernoullies123]

sorry, I read UW-40(f)(5)(f).

 

[bernoullies123]

A good discussion of this is in Section 21.6.1.2 of Companion guide to the ASME boiler & pressure vessel code by By K. R. Rao. An intrepreation is also presented.

The page is viewable here:

http://books.google.com.au/books?id...UW-40(f)&pg=PA70#v=onepage&q=21.14(a)&f=false

 

[jamesl]

Your client is right. There is no need to PWHT in this case. As SnTman said, PWHT is based on weld thickness, not base metal thickness.

Why do you need PVElite to tell you if PWHT is required?Those programs are supposed to automate calculations, not to interpretate code for you to see if PWHT or NDE is required.

 

[EngAddict]

I guess it depends on the Code, AS1210/AS4458 will require anything over (and including) 32mm thick to be PWHT. Usually pretty similar to ASME, sometimes more conservative.