Look in ASME Boiler & Pressure Vessel Code Section IX, Par. QW-420 & QW/QB-422 for listing of P-numbers for materials.

If you referring to P-No's assigned for welding various base materials as described in the ASME Boiler and Pressure Vessel Code, Section IX Welding and Brazing Guidelines, I would suggest you obtain a copy of this guideline. To save on cost, you should just purchase Section IX.

It is a very useful reference to qualify welding procedures and welders for your shop. Section IX will list all code approved material by ASME Specification number, UNS number, general chemical composition, grade or class, and assigned P number.

Perhaps i need to explain:

we are not a company that intends to get involved with the codes, we just need to know what the 'P' numbers relate to so that we can understand our clients requirements better.

Bill www.ukengineeringrecruitment.co.uk

P-5 includes Cr-Mo alloys

P No.s are allocated in ASME to conduct weld procedure qualifications. The idea being that materials with the same P No. have the same or similar weldability, mechanical properties etc.

These are (in general):

P1 - Carbon and carbon manganese steels
P2 -
P3 - CMo and 0.5CrMo steels
P4 - 1Cr0.5Mo steels
P5 - CrMo and CrMoV steels (this is subdivided to 5A, 5B and 5C - 5A are the lower Cr steels e.e 2 - 3Cr1Mo, 5B are higher Cr steels 5 - 9%Cr and 9Cr1MoV and 5C are 3Cr1Mo 0.25V)
P6 - 13Cr

P7 - 17Cr
P8 - austenitic stainless steels
P9 - (A & B) 2.5Ni & 3.5Ni
P10 - quite complicated - various alloys
P11 - 9Ni

You really need the full table to make any sense of some of the P No.s


BUT... there was discussion recently on www.ukwelding.com about P9 codings and this apparently is a British Gas nomenclature for hot tap welding. They may well have a P5 coding that refers to something else.

Depends who your client is. Why don't you ask them?

If you are going to understand your clients needs and weld or supply welders for them (as implied in your original post), it would make sense to follow the advice above and purchase Section IX welding guidelines. It is really not that expensive, and provides a wealth of information.

You will also need to understand the welder qualification groupings for specific electrodes to ensure the welders are qualified for the P number of base materials. These are called "F" numbers.

I think there is a lot of confusion on this topic,
is it ASME Code question or a British Code for gas?

You will probably stay out of trouble if you ask your customer the exact requirements insted of guessing and avoid an expensive mistake.
ER