API 1104- Change in Joint Design

[M.CH]

Hi

According to API 1104 5.4.2.3, "A major change in joint design(e.g from V groove to U groove) constitute an essential variable".

Question: if we have a PQR with single V butt weld (weld type:groove,Joint type:butt)is it possible to support welding of a joint below?

weld type:groove,
joint type:T,
single half V


all other essential variables do not change and technical subject will be met.

 

[DekDee]

If changing from a V groove to a U groove is considered a major change why would you consider a Vee groove (single Vee) to a half Vee groove (single bevel) being anything other than a major change ?

 

[M.CH]

Hi DekDee,

we have two kind of joints:

1-Pipe to Pipe (Groove weld, Butt joint single V)
2-Olet to Pipe (Groove weld, butt joint half single V)

we want to support both by Pipe to pipe PQR. (without any V <===> U)

Thx

 

[DekDee]

You cannot do.
There is not a lot of difference between a V and a U but the code considers that a " major change".
An Olet to a run-pipe is not a butt weld so you cannot use the PQR you have.

 

[M.CH]

Thanks DekDee