Failure analysis on fracture of S13Cr-110 tubing. (August 2018)

• Record Type: Journal Article
• Authors: Liu, Wanying; Shi, Taihe; Lu, Qiang; Zhang, Zhi; Ming, Chuanzhong; Gong, Jianwen; Ren, Jian
• Is Part Of: Engineering failure analysis. Volume 90(2018)
• Page Start: 215
• Page End: 230
• Publication Date: 2018-08
• Subjects: Fracture -- Failure analysis -- Tubing -- Stress corrosion cracking (SCC) -- Microstructure; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2018.03.004
• Languages: English
• ISSNs: 1350-6307

Abstract

Abstract: The tubing is an important component in the oil well, and always serves under the very complex conditions with stress and corrosion. Hence, the failure of tubing often occurs and causes huge losses. In this paper, the failure analysis of S13Cr-110 tubing was carried out and the fracture failure reasons were investigated. Results show that the chemical composition, the microstructure, and mechanical properties meet the API Spec 5CT standard requirements. It is found that the failure cause of S13Cr-110 tubing is mainly attributed to the local stress corrosion after the formation of corrosion pits. Corrosion elements (O, Cl, S, P, Si) and anionic (Cl −, SO4 2−, SiO3 2−, P2 O7 2− ) from annular protection fluid were detected by X-ray diffraction (XRD) and energy-dispersive X-ray (EDX). The corrosion products covered on the fracture surface and sediments in the bottom of pits, and the infiltration in cracks were also analyzed by EDX. The further investigation and analysis reveal that a lot of corrosion pits and dendritic cracks are found on the fracture surface and radial section of the tubing, and many cracks initiate from the corrosion pits on the outer wall of the tubing and some cracks permeat the whole tubing wall. The result of finite element analysis shows that corrosion begins to initiate from the final three external thread where the maximum von-mises stress appears. It is observed that the trans-granular fracture transforms into the inter-granular fracture because of the corrosion. It is caused by the environmental media that are made sure by scanning electron microscopy (SEM), back scattered electron (BSE), and optically metallurgical micoroscope (OMM). As we all know, S13Cr-110 is very susceptive to chloride ion (Cl − ). Therefore, the cause of S13Cr-110 tubing fracture failure is stress corrosion cracking (SCC) which belongs to one of the environmental sensitive fractures. Highlights: Annular protecting fluid may contains harmful components which will lead S13Cr-110 tubing to occur the stress corrosion cracking tendency.