API X52N VS X65

[gkvengat]

Dear Friends,
In my line pipe job as per API 1104 i have X65 grade pipes and i also qualified PQT for that.the problem is anchor flanges pub pieces pipe material is X52N material.IS it required to qualify another PQT for joining X65 to X52 material pipe? please explain the condition as per API 1104

 

[wegm]

Gkvengat,
As per API 1104 a change in base material constitutes an essential variable and for that reason all materials are grouped as follows:
a. SMYS (specified minimum yield strength) =< 42 Kpsi
b. 42 Kpsi < SMYS < 65 Kpsi
c. for materials with SMYS >= 65 Kpsi, each grade shall receive a separate qualification test.
According to the code, when welding materials of two separate material groups the procedure of the higher strength group shall be used. So, regarding your case you can use X65 to X65 procedure in order to weld X65 to X52 provided that all other essential variables are applied. Please have a look at a similar case:

http://www.weldinguide.com/gdanastasiadis/viewtopic.php?f=24&t=435

regards
wegm