This API standard specifies requirements for the qualification, production and documentation of alloy and carbon steel bolting used in the petroleum and natural gas industries when referenced by an applicable API equipment standard or otherwise specified as a requirement for compliance.

The API 20E specification establishes three bolting specification levels (BSL-1, BSL-2 and BSL-3). These BSLs define ascending levels of technical, quality and qualification requirements. Increasing levels of severity reflect increased consequence of bolting failure. The highest level of criticality, BSL-3, is expected to be reserved for those applications in which bolting failure is not an acceptable option. A common definition for BSL-3 application is a “critical application; one through which a bolt failure would result in release of hydrocarbons into the atmosphere.”