Low Strength in High Grade Pipe
- PHMSA issued Advisory Bulletin ADB-10-03 to notify owners and operators of recently constructed large diameter natural gas pipeline and hazardous liquid pipeline systems of the potential for girth weld failures due to welding quality issues. Misalignment during welding of large diameter pipe may cause in-service leaks and ruptures at pressures well below 72 percent of the specified minimum yield strength (SMYS). PHMSA reviewed several recent projects, constructed in 2008 and 2009, with a 20-inch or greater diameter, Grade X70 and higher line pipe. Metallurgical testing results of failed girth welds in pipe wall thickness transitions have found pipe segments with line pipe weld misalignment, improper bevel, improper wall thickness transitions, and other improper welding practices which occurred during construction. Several failures were also located in line pipe segments with concentrated external loading due to support and backfill issues. Owners and operators of recently constructed large diameter pipelines should evaluate these lines for potential girth weld failures due to misalignment and other issues by reviewing construction and operating records along with conducting engineering reviews as necessary.
- PHMSA issued Advisory Bulletin 09-01 to advise pipeline operators of material problems, inconsistent chemical and material properties, that have been found in microalloyed high-strength line pipe grades, generally Grade X-70 and above. The Advisory Bulletin reports some pipe material did not meet the requirements of the American Petroleum Institute (API), Specification 5L, Line Pipe, 43rd edition for the specified pipe grade even though the pipe supplier provided documentation that the pipe met these minimum standards. The Advisory Bulletin suggests pipeline operators closely review manufacturing specifications for the production and rolling of steel plate and that they request detailed Manufacturing Procedure Specifications (MPS), as a basis, to assure critical parameters are controlled throughout the pipe manufacturing process.
- Interim Guidelines for Confirming Pipe Strength in Pipe Susceptible to Low Yield Strength for Hazardous Liquid Pipelines, October 6, 2009
- Interim Guidelines for Confirming Pipe Strength in Pipe Susceptible to Low Yield Strength for Gas Pipelines, September 10, 2009