Bolting Specification Levels for API 20E


  • API 20E was drafted to provide fasteners that are dependable and safe. From the simplest job to the most critical bolting need, API 20E makes sure that a company stays accountable and  takes specific, defined steps to manufacture a high performance product that will go the distance. But not every bolt is built alike, and different jobs call for fasteners that have proved their mettle in more rigorous testing conditions. To address these requirements, API 20E has specified three levels of testing called Bolting Specification Levels (BSL).

      BSL Comparison Chart

    BSL 1: No Cutting Corners, Complying to ASTMs, and Keeping Records

    BSL 1 is the testing level that every fastener should adhere to. It audits a company’s manufacturing and coating process to make sure specifications were followed, protecting bolts from end to end. Furthermore, it requires that companies keep a record of compliance with the specification that can be reviewed if needed.


    Companies that produce BSL 1 compliant fasteners can prove to customers that they produced their fasteners according to specification and that they did not cut corners in the process. When produced properly, all fasteners should be able to comply with BSL1.


    BSL 2: Additional Testing with Stricter Parameters

    BSL 2 includes all of the testing and auditing practices in BSL 1 along with additional testing of all processes to keep a closer eye on fastener production. Aside from the requirements that define the testing— of material, heat treatment, chemistry, mechanical properties, metallurgy, and hardness— both a surface and ultrasonic non-destructive examination must be performed to determine bolt integrity.


    BSL 3: Limits Testing Methods and No Continuous Casting

    BSL 3 is the most rigorously audited fastener in compliance with API 20E. In addition to all testing specified in BSL 1 and 2, BSL 3 limits testing methods to the most precise evaluations. Beyond these tests, BSL 3 also prohibits fasteners that are manufactured using continuous casting techniques. Continuous casting, an efficient and cost-effective way to produce steel fasteners, can create small variables in chemical composition. For BSL 3, these variables are controlled using the ingot casting method. The result is a fastener that has been manufactured with proven reliability and integrity but which is much more expensive.


    What to Buy


    For most bolting needs, a facility only needs fasteners that comply with BSL 1. Procurement professionals can be sure with BSL 1 that a company has manufactured their bolts with end to end oversight, and they have the record to back up their process. BSL 1 bolts can be trusted to keep your team and equipment safe and provide quality bolting solutions at the best value. BSL 2 and BSL 3 give the customer extra assurance, but the additional costs can be prohibitive to bolting budgets. When purchasing fasteners for your next operation, make sure you demand fasteners that comply with API 20E BSL 1.