Deck water spray failure highlighted as one of the main deficiencies on LNG carriers

Deck water spray failure highlighted as one of the main deficiencies on LNG carriers
Deck water spray failure highlighted as one of the main deficiencies on LNG carriers

The US Coast Guard has published an information bulletin about the ongoing issue regarding inadequate deck water spray systems on LNG carriers. US Coast Guard has noted that inadequate coverage of the required areas by a deck water spray system is one of the main deficiencies identified when certificate of compliance inspections are undertaken on these vessels.

The Deck Water Spray system is required by the IGC Code 1993, Regulation 11.3. This requirement text has remained nearly identical back through the GC Code 1983 and to the EGC Code. The new 2016 edition of the IGC Code incorporates the amendments adopted by the IMO MSC at its ninety-third session (May 2014) by resolution MSC.370(93).

These amendments, which entered into force on 1 Jan 2016, consist of a complete replacement text of the IGC Code and will apply to ships whose keels are laid or are at a similar stage of construction, on or after 1 July 2016.

Across the industry, vessel operators and crews have struggled to keep these simple systems operating properly. Ineffective operation of the deck water spray appears easily managed by periodic removal of the installed orifice plates & piping end caps and then flushing the debris from the system. Failure to do this allows for the rapid and substantial build up of debris behind each orifice plate.

This situation, like plaque in an artery, has gone undiagnosed for decades as vessel crews endlessly poke at the clogged nozzles in futile attempts to cure a more severe and untreated issue.

Experience added with the volume of CoC-Gas exams has helped Sector PSCOs understand and accept that individual deck water spray nozzles are likely to be found blocked or ineffective every time a water spray system is energized. Circumstances and design should help dictate the observed severity of a blockage. If one of two nozzles is blocked over a cargo manifold, it is likely a bigger deal than one or two of 12 nozzles covering the same area. PSCOs assess each situation encountered individually and base written deficiencies on “adequate coverage”.

USCG experience has shown that if vessel crews or management are unaware of the orifice plates installed throughout the water spray system, the system will be rendered ineffective within only a few years of construction. This leads to problems and frustration with the ship’s crew, problems during inspections and more importantly an unresolved and tacitly accepted degradation in a significant safety system on these vessels.

For several years we have informally asked Classification societies and Flag Sate Administrations to take a more active role during annual inspections and share this simple fix with no apparent results as failures and inadequacies of this system are still being identified.

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