Do you have deluge system blockages ?

11 August 2015

If you have an offshore installation where deluge effectiveness is reduced due to nozzle blockages, HSE Research Report 1046 may help.

But it’s a useful guide mainly for the novice – anyone who has lived with the issue for a while (and it was a significant concern in UK sector even before the 1988 Piper ‘A’ tragedy – see the Cullen Inquiry report paras 12.12-12.23) is likely to know most of the conclusions already. Also it’s mainly a literature survey, rather than new research and, despite requests, very few operators contributed their practical experiences.

The main findings are:

  • There’s no evidence that cleaning mechanically sound deluge pipework is likely to result in damage to that pipework.
  • There’s no evidence to suggest that any one cleaning method is more suitable than another.
  • Corrosion observed in deluge systems is due to long term exposure to seawater following wet testing. (NFPA 25 requires at least annual testing to confirm spray patterns and delivery rates).
  • Where practical, flushing deluge piping with potable water after wet testing is recommended to remove pooled sea water and salt deposits.

But it’s a good guide for those with limited experience, in any geographical area. It outlines how blockages can arise and the range of options to both design out the problem and to minimise its severity.

It’s also worth noting that, though corrosion is the primary cause, at least one operator said they had problems with fish sucked into the fire water pump and the resulting debris in deluge pipework. So don’t forget to inspect and maintain your inlet filters!

Ian Waldram

CFIOSH