HSE Warns Offshore Industry About Deck Grating Failures
Composite fire-resistant materials, particularly deck gratings, may lose their load-bearing capabilities after relatively short exposures to hydrocarbon pool fires, the agency warns.
The Offshore Division of the Health and Safety Executive's Hazardous Installations Directorate is warning stakeholders that testing shows composite fire-resistant materials, notably deck gratings, may fail after relatively brief exposures to hydrocarbon pool fires. The time involved is "considerably shorter than the specified resistance period of 60 minutes derived from the certifying test for cellulosic fires," the British safety authority noted in a new Safety Notice.
The notice says these gratings are certified against U.S. Coast Guard specifications PFM 2-98 and NVIC 9-97-CH1 (U.S. Coast Guard Navigation and Vessel Inspection Circular 9-97, Guide to Structural Fire Protection, and U.S. Coast Guard Policy File Memorandum on the use of Fibre Reinforced Plastic gratings and cable trays, PFM 2-98), which employ a combination of load tests and a 60 minute "fire" exposure to a test furnace to mimic the heat profile of a cellulosic, rather than a hydrocarbon fire. Celluosic fires have slow growth times and may reach a temperature of 880º C after 60 minutes, compared to hydrocarbon fires which can typically reach temperatures around 1,100º C significantly faster. Hydrocarbon jet fires will produce even higher temperatures within even shorter times.
"Tests by the Health & Safety Laboratory (HSL), on behalf of HSE, have determined that certain types of FRP gratings based on a glass reinforcement embedded in a phenolic or isophthalic resin may lose their load-bearing capabilities or fail after exposure to hydrocarbon pool fires. The tests show that the fire duration required for this failure or weakening is substantially shorter than for cellulosic fires against which the composite materials were certified. These tests also identified the possibility that the grating may appear to have retained its integrity post-fire, but may actually have insufficient strength to support the dynamic loading arising from persons walking/running over it," the agency warned.
The notice directs offshore duty holders to determine whether composites are being used in locations where they could be exposed to hydrocarbon fires. If they are, the duty holders must consult with manufacturers or suppliers and determine whether sufficient integrity will remain for them to be used safely.