Woodside offshore dry deluge testing

Abstract

Wet deluge testing of firewater systems is considered a recognised contributing factor to accelerated corrosion on offshore facilities. Spraying sensitive equipment and structures with sea water is not only disruptive to the facility, it can also cause process upsets and is labour intensive with set-up and subsequent fresh water washdown. While ensuring the performance of this safety-critical system is vital through regular testing, adopting new methods with less adverse impacts is of high importance. Dry deluge testing using a propylene glycol-based vapour as an alternate testing medium has been adopted on offshore facilities in the US, Dutch, Danish and UK sectors, significantly reducing the frequency of wet testing. A generator is used to produce smoke-like vapour, which is then pumped into the system piping through existing test connection points while the system remains online. The vapour migrates throughout the distribution piping, ultimately exiting the deluge nozzles to visually identify any blockages. This method of testing will reduce costs to businesses, not only for deluge testing itself, but more importantly from an asset fabric maintenance perspective. Woodside Energy successfully carried out the first offshore dry deluge testing in Australia on the Okha FPSO (floating production, storage and offloading) in 2021. The testing covered varied deluge and foam system arrangements with different nozzle types. This paper details the dry deluge tests conducted on Okha, the results gathered, main operational and implementation concerns of the testing and recommendations on further collaboration and improvements for adopting this test method across the Australian oil and gas industry.