Leakage analysis of steel wire reinforced polyethylene composite pipe used for waste water transportation

• DOI: 10.1016/j.engfailanal.2021.105750
• Publication Date: 2021-09-16T15:45:50Z
• Authors: Xuemin Zhang; Lin Hou; Houbu Li; Guoquan Qi; Dongtao Qi
• Keywords: Leakage (economics); Cladding (metalworking); Pipe; Hydrostatic pressure

Abstract Leakage failure had occurred near the electrically melted sleeve of steel wire reinforced polyethylene composite pipes (SRTP, DN200 PN1.6 MPa) which was used for waste water transportation in oilfield. In order to study the actual reason of failure and then propose the suggestions for failure prevention, the correlation characteristics of inner HDPE pipe, SRTP and the melted sleeve are analyzed. Morphology, composition and thermal property of the resin in composite pipe were systematically studied by using OM, FTIR, VST, OIT, etc. Flattening property, longitudinal reversion, short-term hydrostatic strength and burst pressure of the used SRTP were tested, and the morphology of the melted sleeve was observed in detail. Results revealed that polyethylene still has a smooth morphology and exhibits no obvious composition change after several years’ usage. Thermal property of the resin and basic property of the composite pipe satisfy the corresponding standards. However, there are some visible over-weld traces in the connection part between two pipes. Over-weld of the sleeve can destroy the cross-section structure of the composite pipe. Therefore, transported liquid media can penetrate into the reinforcement layer and cause corrosion of the reinforced steel wires. Internal pressure resistance at the melted sleeve of the composite pipe thus decreases obviously, which finally leads to a burst failure of the pipe.