Susceptibility to cracking in sour service is usually determined by testing in laboratory or simulated service environments, in compliance with NACE MR0175 / ISO 151561. Typically small scale specimens are extracted from sampled material to facilitate uniaxial tensile, C-ring or 4-point bend testing to determine the resistance to Sulfide Stress Cracking (SSC) or Stress Corrosion Cracking (SCC). Sampling relaxes residual stress and in many cases the specimen is not representative of the material surface condition and microstructure, and clearly may not represent material with inhomogeneous properties. This is particularly true for subsea lines installed by reeling as strain history varies around the entire circumference. A full ring ovalization test method was developed in the 1980s / 1990s, which retains the residual stresses, is better able to assess behavior with hoop stress and is still favored today (BS 87012), but it does not load the entire specimen. This paper describes a new axially loaded full ring test method which was developed and demonstrated to combine the benefits of retaining a full as-welded pipe pup-piece, permitting single-sided exposure, with the advantage of tensile loading of the complete tubular specimen.

Subject
Test methods, Pipe surfaces, Steel surfaces, Materials, Piping, Manufacturing, Yield stress, Welding, Girth welds, Stress, Sulfide stress cracking, Stress corrosion cracking, Residual stress
Keywords:
Full ring, sulfide stress cracking, SSC, stress-orientated hydrogen-induced cracking, SOHIC, stress corrosion cracking, SCC, OTI 95 635, BS 8701, sour service
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2017
Association for Materials Protection and Performance (AMPP)
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