Failure of a ½” BSP cap under pressure on well service work

  • Safety Flash
  • Published on 1 November 1999
  • Generated on 23 June 2025
  • IMCA SF 06/99
  • 1 minute read

The following incident was recently reported to us. It occurred on an offshore installation where the half inch BSP cap appears to have blown off a pressure testing manifold under approximately 1200psi of water pressure.

Our member’s investigation revealed the following:

The cap and BSP/NPT connector were rated to 45000psi. The cap was not found, so the conclusions are based on the following assumptions:

  1. The cap was not fully engaged.
  2. It was over-tightened.

The key lessons learned from the incident were identified as:

  1. Be aware of the ratings, tightening procedures and limitations of all pressure fittings used in a temporary pressure system.
  2. Pressure fittings should be in good condition prior to use – in particular, threads should be free of paint and debris. If in doubt, use new fittings.

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