Failures in seamless carbon steel pipe, fittings and flanges during hydrostatic testing was announced in a technical bulletin released by the National Certified Pipe Welding Bureau.

The failures result from changes in steelmaking practices by certain mills over the last five years.

"Unlike the 'Chinese flanges' issue in the 1990s, analysis of these failures showed that there was no obvious correlation with location of manufacturer or country of origin," the bulletin states.

The bulletin recommends that, except when the piping system hydrostatic test pressure is less than 20 percent of the code maximum allowable pressure, contractors should include a requirement in their purchase orders that seamless carbon steel pipe, fittings and flanges have a manganese-to-carbon ratio of 5:1 or greater and a grain size of 7 or finer to avoid such failures.

Read the full bulletin here.