The Oil Well Pipe To Sulfide Stress Cracking Double Cantilever Beam Method Pilot Study

The problem of sulfide stress cracking (SSC) can not be neglected for material failure in the oil-gas production. At present, there are many documents about SSC. The National Association of Corrosion Engineering (NACE) has made the standard of the material SSC evaluation. In the standard of NACE TM0177-2005, method A and method B are the most extensively applied. In the standards of ISO11960 and ISO15156 etc., steel critical stress intensity factor of environment fracture toughness in the H₂S environment is listed, The fracture toughness can be obtained from the experimental method of Double Cantilever Beam (DCB), which is NACE method D. But the method D is not still carried out, so there will be some incompleteness in evaluation and engineering design of material. This article tries hard to establish the DCB experimental technique and the technical specification, which completes the DCB experimentation and solves the engineering question. In the chapter 4 of this article details descript the principle, method and the data processing of DCB experimentalThis paper introduces Laboratory Testing of Metals for Resistance to Stress Corrosion Cracking in H₂S Environments NACETM0177-2005 standard. The method A and B are commonly used to determine the material SSC resistance performance in the crack time. But method D ,in fracture mechanics presents material SSC resistance behavioral specific indices Kissc that can also be applied to fracture mechanics calculation. Then method D can combine modern design method with fit for purpose evaluation, thus this paper introduces the evaluation of fit for purpose in fracture mechanics. The evaluation is important for OCTG. In order to maket fit for purpose evaluation, we need learn about the fracture mechanism in H₂S environment. For emergent crack of pipe , stress intensity factor is calculated .Therefore, chapter 2 introduces SSC mechanism in H₂S environment about material . Chapter 3 introduces stress intensity factor calculation which uses finite element method combining with fracture mechanics methodThe main contents in this paper is leading theme of mechanical and environmental behavior of tubular goods, which has exploratory and innovation. Especially, the DCB experimental investigation in the H₂S environment is firstly studied in our country, There is no reports about the relevant experimental investigation.DCB testing method provides condition for modern design and method of integrality supervisory. The fit for purpose evaluation of OCTG is established in the fracture mechanics. Therefore, this paper puts and carries out the study of fit for purpose evaluation of OCTG. The research technique and computation also has some problem to study, but it will be a good beginning and a good future.