4.1 This test method describes the testing procedure that shall be used to qualify a coating system that is under consideration for use on ASTM A490 high strength structural bolts made of any steel composition permitted by the A490 specification. The test method measures the susceptibility of coated specimen bolts to the influence of an externally applied potential (see 7.2.3.3) by testing for the threshold of embrittlement in a salt solution environment.

1.1 This test method defines the procedures and tests to evaluate the effect of a coating system on the susceptibility to environmental hydrogen embrittlement (EHE) of an ASTM A490 high strength structural bolt.

1.2 This test method shall qualify a coating system for use with any size of A490 bolts (that is, ¹/₂ to 1-¹/₂ in.) high strength structural bolts, relative to EHE.

1.3 The characteristic to be evaluated by this test method is the susceptibility to EHE caused by hydrogen generated from corrosion protection of the steel bolt by sacrificial galvanic corrosion of the coating. Testing shall be performed on coated, specimen ASTM A490 bolts manufactured to the maximum susceptible tensile strength values (see Table 1) of the bolt (see Section 5 Specimen Bolt Requirements). The internal hydrogen embrittlement (IHE) susceptibility will also be inherently evaluated when the EHE is tested through this test method. There is no need for a separate IHE susceptibility test.

1.4 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.