scope:

This API standard specifies requirements for the qualification of suppliers of machining services where API product standards require such services or are otherwise specified as a requirement for compliance. Compliance with this standard is not required to demonstrate compliance with any other API standard or specification.

This API standard establishes the requirements for three machining qualification levels (MQL 1, MQL 2, and MQL 3). These three MQL designations define different levels of quality and qualification requirements. These MQLs are numbered in increasing levels of requirements in order to reflect increasing quality and qualification criteria.

Final assembly, component testing (e.g. nondestructive examination, pressure testing) or a broker of machining services are outside the scope of this standard.

This standard applies when specified by the customer or voluntarily followed by the machining services supplier.

NOTE This standard does not limit the responsibility of any manufacturer of commercial products utilizing machined parts and manufactured to an API standard from its responsibility for compliance with all applicable requirements of that API standard.