NORSOK standards were developed by the Norwegian petroleum industry to ensure safety, add value and promote cost effectiveness for petroleum industry operations, particularly under the harsh conditions encountered during offshore drilling in the North Sea. But companies operating in less hostile environments can also benefit from the stringency of these requirements.


NORSOK M-650, Qualification of Manufacturers of Special Materials, establishes a set of requirements to verify that a manufacturer has the equipment, procedures and controls in place to produce material with acceptable properties.

The standard mainly applies to duplex and high-alloy austenitic stainless steel in all grades, product forms and dimensions.  It also applies to castings made of nickel-based alloys, titanium and titanium alloys.  In special cases, the standard may also be used to oversee special manufacturing processes for critical components made of other materials.

NORSOK M-650 outlines that the purchasing company rather than a third-party inspector performs the audit to ensure that a manufacturer meets the qualification requirements. When the process is complete, both the purchasing company and the manufacturer sign a Qualification Test Record (QTR) that is valid for two years following the initial qualification. Subsequent qualifications last for five years.

One distinguishing feature of the NORSOK qualification is the overall emphasis placed on the manufacturing process and the final product. The NORSOK standard is route-specific to ensure that the manufacturer has the knowledge, equipment, processes and procedures necessary to repeatedly produce finished products for use in critical applications.

The NORSOK standard puts a large emphasis on proper heat treatment. Variables such as the consistency, uniformity, calibration, correctness and efficiency of the furnaces themselves must be qualified. Documentation must also be provided for furnace loading, measurement of heat treatment temperature and soak time at temperature using contact thermocouples. Quenching processes must be specified as well as the uniformity and consistency of the quench.

Finally, the qualification requires extensive non-destructive and destructive testing of products representative of the heat and heat treatment batch from which they have come. The location of the test samples and the results of testing are also fully documented and recorded within the documents supporting the QTR. NORSOK M-650 requires that laboratories performing the testing have a quality system in accordance to ISO 17025 or equivalent and that these laboratories hold a national accreditation.

Each QTR is specific to a particular alloy, production route, product form (i.e. seamless tubing) and product thickness. Taking the example of seamless tubing, a change in any of the items below requires re-qualification of the manufacturing process:

  • Maximum product thickness and weight
  • Material grade
  • Melting and refining equipment
  • Manufacturers of start materials
  • Location of plants or sub-contractors
  • Manufacturing equipment
  • Heat treatment process

Products produced during qualification and in production lots must meet the requirements set forth in the appropriate Material Data Sheet (MDS) of NORSOK Standard M-630.  In the case of seamless tubing, type 6Mo (UNS S31254), the MDS, R18, outlines the required specifications or processes for the:

  • Qualification
  • Manufacturing Process
  • Steel making process
  • Heat treatment
  • Corrosion testing
  • Marking
  • Certification

MDS R18 also states that the finished product should also comply with ASTM A269, Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service.


As a buyer looking to procure NORSOK-qualified materials, look for manufacturers that have been qualified by reputable companies with established connections to end-users in the petroleum industry.  Ensure that the qualification is current and applicable to the products to be purchased.

It takes an experienced manufacturer with a dedicated team of Quality and Engineering personnel to fully understand the precise details of NORSOK M-650 and M-630.  Once the requirements are fully understood, it takes a highly skilled workforce to implement the processes and procedures required to manufacture NORSOK-qualified products.