Pipeline Steel In Artificial Sea Water Containing H_2S: Resistance To Stress Corrosion Cracking Induced By Hydrogen Sulphide

摘要

In Black Sea water the content of Hydrogen Sulphide is varying both in water mass and in floor sediments. In general the presence of Hydrogen Sulphide is explained by the activity of anaerobic and desulphuric bacterias. Taking into account the possible implementation of project which would involve laying main gas pipeline on Black Sea floor, the study of the extent of potential damage which may be caused to the appropriate pipeline steel material by Hydrogen Sulphide-saturated sea water seems well reasonable. In doing so it would be necessary to evaluate also the extent of a sea water pressure impact affecting the process of a Hydrogen Sulphide-related erosion of pipeline steel material. Tests to evaluate Stress Corrosion Cracking (SCC) resistance of pipeline steel specimens were performed with the use of a special Testing Autoclave intended for making SCC tests in corrosion aggressive environment by application of Slow Strain Rate Test Method. The tests were performed under atmospheric air pressure and hyrdostatic pressure which was equal to 25 MPa. Experimentally derived results evidence that the artificial sea water close by its chemical composition to the natural Black Sea water promote SCC of a standard commercial pipeline steel grade X70. Hydrostatic pressure of liquid environment equal to 25 MPa intensifies the process of Hydrogen Sulphide-related deterioration of the steel material studied.