The construction code for process piping is ASME B31.3 Code and it covers the minimum requirements for design, materials, fabrication, inspection, testing, and commissioning.
With the above explanation, your inspection and test plan (ITP) for process piping needs to meet the requirements of ASME B31.3 Code.
ASME B31.3 refers you to the other ASME code sections for some activities. For example for welding refer to the ASME Code Section IX, pipe fitting design and selection to the ASME B16.5 and for Nondestructive testing to ASME Code Section V.
The process piping design and construction is not under the ASME Code scheme of stamped items.
It means there is not certification for construction contractors by ASME, and it is the responsibility of owner to select a qualified and experienced contractor for its process piping construction project.
This is the reason that in the ASME B31.3 code you cannot see the wording of “Authorized Inspector,” and instead the words “owner inspector” have been used.
The owner inspector can be the owner’s own qualified inspector or the inspector of a third party inspection company under contract with the owner.
Throughout the ASME Construction codes, when you see the words “authorized inspector,” you notice there is an ASME Stamp scheme there.
Contrary to the ASME B31.3, the ASME B31.1 code for power piping (boiler external piping) have the ASME stamp scheme. The construction contractor must be certified by the ASME organization and must hold the “PP” stamp.
So the wording for inspector in the ASME B31.1 is “authorized inspector,” which means that this person has specific qualifications and a commission card from NBIC.
For more details, review the Pressure Vessel Certification article. The certification process for the power piping contractor is similar to the pressure vessel.
The detail of inspection requirement in the construction field is addressed in the process piping inspection and test plan.