08109 Effect of NACE TM0284 Test Modifications on the HIC Performance on Large-Diameter Pipes
The test method described in NACE TM0284-2003 'Evaluation of Pipeline and Pressure
Vessel Steels for Resistance to Hydrogen-Induced Cracking (HIC)' is intended to provide
reproducible test environments capable of distinguishing the susceptibility of different steel
samples to HIC in a relatively short time. Recently, several significant modifications have been
made or proposed to the test procedure of this standard. Amongst others, these modifications
affect the test solution chemistry, pH limitations and solution volume to specimen surface area
ratio. Frequently, the acidified acetate buffer test solutions, as proposed in the EFC 16
recommendations and initially intended for use in sulfide stress cracking (SSC) tests, have
been adopted for HIC testing. A frequent difficulty associated with the EFC 16 test solution A
(pH 3.5) is the requirement of pH drift limitation within 0.1 pH units. The paper describes how
to overcome the difficulty of frequent manual pH adjustment by automation of pH control and
adjustment. Other HIC test modifications, e.g. with regard to changes in solution volume to
specimen surface area ratios are also addressed. Based on the test results, the need for
sophisticated modifications of the NACE TM0284 standard HIC test is discussed.
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