How important is NORSOK M-650 Qualifiaction?
Divergence between M-630 and Oil Company / Main Contractor Requirements
M-630 revision 6 in October 2013; re-issued in April 2014. The April changes were non trivial; neither the standard nor the material data sheets were up-issued and no one was advised of the change.
A consequence of the October 2013 and April 2014 revisions is a growing divergence between the material data sheet requirements in NORSOK M-630 and Oil Company specification requirements. The following comments are indicative of the differences
Test Locations
Typically "test specimens at 1/4T", additional testing "near centre or inner wetted surface"
Chemistry
Typically Nitrogen content 0.14 - 0.20%, Sulphur < 0.005% and minimum PREN values. the calculation of PREN is dependant on the standard being used and differs in NORSOK, NACE and API.
Charpy V-notch
Typically Test requirement 50J average, 40J minimum at -50C
There are examples of test temperatures at -60C and in the future maybe -75C.
In NORSOK; 45J average, 35J minimum at -46C
Microstructure
Typically "shall be free from intermetallic phases and precipitates".
In NORSOK; microstructure is no longer a definitive failure mode; acceptance of the product shall be based upon the G48 Corrosion and Charpy V-notch test results".
G48 Corrosion Test
Typically "no pitting", test temperatures 25-40C
In NORSOK; test temperatures 25-50C
Additional Testing not part of NORSOK
Transverse testing at thickest point
Transverse testing at maximum design temperature
Ultrasonic examinations of forgings
The NORSOK M-650 Qualification is a stepping stone to ensure that manufacturers are competent and capable in 'special materials'; duplex stainless steels, highly alloyed austenitic stainless steels, nickel base and titanium alloys.
A copy of our presentation "Implications of NORSOK M-650 Standard in the Offshore Industry" is attached
NORSOK M-650 is a qualification not an accreditation.