In order to become more cost efficient the Norwegian authorities initiated in the early 1990’es a standardisation project for the upstream oil and gas industry. One of the important products from the project was the NORSOK M-001 standard which addresses the material selection for offshore production facilities. A new international standard – ISO 21457 – based on the same principles as NORSOK M-001 was published in 2009 and the latest version of NORSOK M-001 only gives clarifications to the international standard. ISO 21457 adopted important user limits from NORSOK M-001 for materials in selected services in addition to that some new limits were defined. Example of limits for corrosion resistant alloys are maximum operating temperature to avoid stress corrosion cracking in marine atmosphere maximum operation temperature for sea water service and utilisation limits in order to prevent hydrogen induced stress cracking from cathodic protection. These limits are based on a combination of field experience and laboratory testing as well as the industry must incorporate certain conservatism in order to operate safely. The technical justification for the limits will be presented and discussed.