Environmental Cracking Failure Analysis of Stainless Steel Threaded Joint in Rotary Steerable Tool
Year: 2026
Type: article
Abstract: Axial cracking in threaded joints of rotary steerable tools is a critical but under-investigated failure mode that can severely disrupt shale gas drilling operations. Understanding its root cause is essential for prevention. This study aims to determine the cause of an axial cracking failure in an S35150 austenitic stainless steel threaded joint from a field operation. A comprehensive analysis was conducted, integrating physicochemical characterization of the failed joint. The stress corrosion behavior of the threaded joint in a simulated corrosive environment was evaluated via four-point bend (FPB) and double cantilever beam (DCB) stress corrosion tests. The results showed that the material exhibited high susceptibility factors: a hardness of 38.5 HRC, a yield-to-tensile ratio near 1, and a P content exceeding the standard. Fracture surface analysis revealed an intergranular morphology with substantial chlorine (0.78%) and sulfur (0.93%) contents, indicative of stress corrosion cracking (SCC). The laboratory tests results demonstrated that the threaded joint had poor crack resistance: the fracture toughness value of the specimen measured by the DCB test was 24.14 MPa·m0.5, and all specimens fractured during the FPB.
Source: Processes
DOI: 10.3390/pr14040684
Institutions: Southwest Petroleum University, CNPC Chuanqing Drilling Engineering Company Limited (China), China National Petroleum Corporation (China), State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, PetroChina Southwest Oil and Gas Field Company (China), Research Institute of Natural Gas Technology
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,896
OpenAlex ID: W7130364377