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Amaro, Robert L.

Bradley, Peter E.

Connolly, Matthew J.

Lauria, Damian S.

Looney, Chris P.

Martin, May L.

Slifka, Andrew J.

English

Engineering Conferences International

STRAIN-LIFE TESTING IN HYDROGEN; ADAPTING EQUIPMENT FOR FULLY REVERSED LOADING OF PRESSURE VESSEL STEELS IN HYDROGEN  Peter E. Bradley, National Institute of Standards and Technology, Colorado, USA Andrew J. Slifka, National Institute of Standards and Technology, Colorado, USA Damian S. Lauria, National Institute of Standards and Technology, Colorado, USA Matthew J. Connolly, National Institute of Standards and Technology, Colorado, USA May L. Martin, National Institute of Standards and Technology, Colorado, USA Chris P. Looney, Advanced Materials Testing & Technologies, Alabama, USA Robert L. Amaro, Advanced Materials Testing & Technologies, Alabama, USA    Steels employed in pipelines and pressure vessels (storage and transportation) are susceptible to hydrogen embrittlement.  Decades of study on the embrittlement of these steels has elucidated numerous mechanisms that may be involved, singly or in combination, during exposure to hydrogen gas in operation.  Recently, a technique for separating effects of hydrogen on the elastic and plastic response to mechanical loading, known as strain-life testing, has been employed at NIST to evaluate the mechanical properties of a DOT 3AA cylinder pressure vessel steel most commonly identified as modified AISI 4130 (25CrMo4) steel.   Fully-reversed strain-life testing is often referred to as non-trivial or challenging.  This is never more so than in the presence of hydrogen gas where a pressure chamber is employed. Such instrumentation is usually only designed for operation in tension where the challenges are generally understood. When testing in tension, the specimen and load-train naturally align so slight misalignment presents no issue.  However, strain-life requires very good alignment of specimen and load-train to eliminate off-axis loading during load-reversal (from tension to compression).  Strain-life test methodology from ASTM E606 provides guidelines for sensors and alignment relevant to the constraints and limitations presented by the chamber, load-train, and specimens.  We present adaptations to the equipment, alignment of both chamber and specimen, and the alignment of the interior and exterior load-train couplings. Tests of 4 different alloys were successfully conducted in high pressure hydrogen gas at 21 MPa undergoing fully-reversed strain-controlled loading.  

Strain-life testing in hydrogen; Adapting equipment for fully reversed loading of pressure vessel steels in hydrogen

https://dc.engconfintl.org/cgi/viewcontent.cgi?filename=0&article=1077&context=hydrogen&type=additional

Strain-life testing in hydrogen; Adapting equipment for fully reversed loading of pressure vessel steels in hydrogen

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Engineering Conferences International