Stress analysis aspects of the development of a standard test method for sour service testing

• Published in: Corrosion science 1993, Vol.35 (1), p.541-548
• Main Authors: Fowler, C.M., Burdekin, F.M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Corrosion; Corrosion tests; Exact sciences and technology; Metals. Metallurgy
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/0010-938X(93)90187-L

The testing and assessment of the suitability of pipe materials for sour service is the subject of many publications and reviews. Since it is not practical to test all materials and welds under full scale service conditions, then appropriate simulations have to be employed. This involves the use of well characterised test environments and simulations of the mechanical stress levels encountered by the material in practice. Small scale tests using three point bend and U-bend samples have many disadvantages, particularly if hydrogen permeation studies and welding residual stress effects are also required. CAPCIS, as part of its consultancy and testing service has, over a number of years, developed a laboratory-based test which represents more realistically the real life mechanical loading than the smaller scale tests. The test uses a full ring of candidate pipe material, with longitudinal and circumferential welds, containing the agreed test solution. Prior to test, the sample is loaded mechanically by an internal jacking arrangement to produce a stress level calculated on the basis of the service and pipe laying conditions. A gradation of stress around the circumference of the test sample is produced. The paper describes the basis of the stress calculations employed.