Chris, I understand your question. What would be the application for which you want to use this WPS? Most WPSs I know of, say for structural welding or pressure equipment, won’t accept this part of ISO. I think the applications are practically limited.

Hi, and thank you for your answer.
Well, my company is manufacturing instruments to many types of industries. You say that this part of ISO is limited, is it said so in relevant standard (for example in relevant piping standard)? Or how do you know that you can't use this standard to qualify a WPS?

Most engineering codes, like EN 13445 and EN13480, require third party approvsal on welding procedures/qualifications for pressure retaining items. This is inline with the PED, which makes sense since both standard are harmonized.
EN 13445-4:2018 e.g. says:

Quote:

7.3 Welding procedure qualification record (WPQR)
Welding procedure specifications to be used in production shall be qualified by reference to an appropriate WPQR.
...
.
...
For welds other than pressure retaining welds directly attached to the pressure vessels e.g. tray rings, support feet,
etc. welding procedure specifications may be acceptable by holding welding procedure approval records carried out
in accordance with EN ISO 15611:2003 and EN ISO 15612:2004.

Same goes for EN 13480

Quote:

9.3 Welding procedures
9.3.1 Verification of suitability
The suitability of the intended welding procedures shall be verified on the basis of a welding procedure
qualification in accordance with Table 9.3.1‐1.

Table 9.3.1-1 does list EN ISO 15611:2003 for PED category 0 (i.e. art 4.3) and I. More specifically, for category 0 resp. I;

Quote (category 0)

Welding procedures in the pressure envelope shall be qualified in accordance
with EN ISO 15614‐1:2004, EN ISO 15611:2003, EN ISO 15612:2004 or
EN ISO 15613:2004.
Welding procedures in non‐pressure retaining parts shall be qualified in
accordance with EN ISO 15610:2003.

Quote (category I)

Welding procedures for the pressure envelope shall be qualified in accordance
with EN ISO 15614‐1:2004 or EN ISO 15613:2004 as relevant unless the design
specifications specify that EN ISO 15611:2003 or EN ISO 15612:2004 is
acceptable.

What it boils down to, I guess, is that if the product your designing is not covered by any standard, you usually are 'free' to choose whatever you like.

What you typically see in the industry is that companies either have qualified WPSs'en WPQ's, acc. EN ISO 15614 resp EN ISO 9606. For work or products not requiring a qualified WPSs, companies often dont bother making a WPS at all, hence you dont see EN ISO 15611 a lot.