American Petroleum Institute

STEEL DETERIORATION IN HYDROGEN
 N 940

Annotation

Introduction

The research at the University of Wisconsin sponsored by the API Subcommittee on Corrosion has been reported in eight technical papers published in the Proceedings of the American Petroleum Institute. 1a The work at the University was directed by F. H. Vitovec. The first project was aimed primarily at explaining the incubation period, during which initial hydrogen exposure does not appear to damage steel, and also the effect of various factors on the incubation time and on the rate of deterioration of properties after observable attack has begun. The second project sought to explain the effects of hydrogen on creep rate and creep rupture strength of alloy steels under conditions that produce little or no attack on the same steels when they are not stressed. In the course of experimental work many data on effects of pressure, temperature, steel composition, and other variables were obtained, and many were published in the papers by Dr. Vitovec and his colleagues. These new data made it possible for the present writer to develop and publish a set of curves supplementing those in his previously published "Operating Limits for Steels in Hydrogen Service." The new curves 10 showed the time for incipient attack on carbon steel and on carbon 0.5 percent molybdenum steel at temperatures and pressures exceeding the limits of the curves previously established as guides for indefinitely long, safe operation. The research has also produced invaluable information on the effects of strain in promoting attack. The loss in strength of carbon and low-alloy steels when exposed to hydrogen while in the temperature range of creep will be of importance to engineers and code-writing bodies when they are specifying steel for this service. Thus practical applications have been made of the Vitovec work, and more are indicated.

a Refers to REFERENCES on p. 14.