Publications
| Title | | Authors |
|---|---|
| Test methodologies for the study of near neutral stress corrosion cracking in pipeline steels « back |
E Senigallia and M Pontremoli |
| 12th PRCI/EPRG Joint Technical Meeting, Groningen, Holland, May 1999 | |
| This report deals wiih the research of a standardised methodology for laboratory evaluation of Near Neutral SCC (NNSCC or even called low pH SCC). This phenomenon has gained an increasing interest among both gas companies and steel producers in the attempt to avoid failures and minimise the risk associated with it. Two major objectives can be pointed out. The first one refers to existing pipel'me and it is to identify the areas with the highest risk of NNSCC, so that appropriate measures can be taken. For future pipelines, the aim is to produce guidelines for pipe materials, coating, environment and operating s e ~ c teo reduce the risk of NNSCC. One heavy obstacle to an effective Progress in the research is however the diff~cultyto reproduce in a consisient and reliable way the cracking panem and the mechanism actually observed in the field experience. A research project was therefore launched late 1996 under the supeMsion of EPRG Co~~osioCno mmittee involving four laboratories (namely British Gas R&D, British Steel Swinden Lab, Saltzgitter (former Preussag Sthal) and CSM) with the scope, in a fist phase, of defining and developing a standardised experimental methodology to obtain reliable data for crack initiation and propagation. A good consistency and reproducibility among the dinerent laboratories was achieved but the difiicuily for a quantitative assessment of NNSCC was however coxdirmed. Crack like featnres resuiting fiom test exposure were observed in 53% of the tensile specimens with apparent crack depths of up to 70pq as well in 43% of the CT specimens. Despite such limitations both developed test methodologies can be profitably applied for investigating the phenornenon. Based on such conclusion a second phase of the project is presentiy under preparation by EPRG, where the developed test procedures will be used to examine the effect of a range of metallurgical factors on NNSCC. | |
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