5.1 General

For functional and economical reasons projects may need special components not defined in this standard or new combinations of defined components in new piping classes. For introduction of new components and piping classes, the numbering system as defined in section 1.5 shall be maintaned.

5.2 New piping classes

Projects may need piping classes not included in NORSOK standard. However, adding or removing components on the PCS shall not be regarded as a new piping class subject to renumbering if the function of the PCS is unchanged with respect to pressures, temperatures and services. However, all projects and operators must fill in the name of operator and the project identity code as described in section 4.2 on all pipe classes also on those unchanged from the NORSOK PCS.

New piping classes for intermediate pressure/temperature ratings shall use X, Y or Z as 5th og 6th character leaving the four other characters identical to NORSOK PCS with the standard class rating above.

New piping classes to fit a special service defined or not in annex A, shall have a different 4th and/or 6th character form the NORSOK piping class.

5.3 New valve data sheets

For standardisation purposes new valve data sheets should not be defined for any intermediate pressure/temperature rating according to new piping classes. An intermediate valve rating requiring a new VDS should be limited to pressure/temperature ratings above ANSI class 900 and as defined in ASME B 16.34, except that it shall not be limited to welding end valves. Valves with hubs for mechanical joints or with other special ends may be intermediate rated. This does not apply to valves with standard flanged ends to ASME B 16.5.

New project specific valves which are not interchangeable with standard NORSOK valves shall be identified with a letter in the sixth character, see clause 4.7.