Electric resistance welded (ERW) pipe has been used successfully for many years in a variety of industries, such as the oil industry. However, frequent failures over the years along the ERW pipe during operations, including hydrostatic testing of pipelines and hydraulic fracturing of oil and gas wells through casing, have caused concern over the reliability of ERW pipe. Numerous analyses performed during several years on ERW failures have demonstrated that many are the result of either inadequate bonding or complete lack of bonding at the weld line. Furthermore, welds that fail at low pressure often were not heat treated subsequent to resistance welding. Postweld heat treatment is not required for many grades of low strength ERW pipe, i.e., ASTM A120. Morever, API 5L grades are not required to be heat treated. The only requirement is that no untempered martensite be present after welding.
展开▼
