Bestobell Marine has secured approval of its new DN350 and DN400 cryogenic globe valve designs, developed specifically for the marine sector. This means that the valves are now fully tested and certified for installation on liquefied natural gas (LNG) carriers.
Duncan Gaskin, sales director for Bestobell Marine, says: 'Shipowners are increasingly requesting that shipyards use higher capacity pumps for discharging cargo from LNG carriers, because it speeds up the unloading process. The cryogenic globe valves which are used for controlling the flow on the discharge line need to increase in size to accommodate the higher flow rates. We are delighted to be one of the first valve manufacturers to secure this approval and look forward to further developing our business in this area.'
The fire test procedure is a rigorous process, which exposes the valve components to temperatures of over 1,000⁰C, with the valves having to demonstrate that they will not leak gas to the atmosphere and through the valve seat. This can only be achieved by designing the valve to proven firesafe standards, with an all metal seat construction and using graphite gaskets and packings that are not affected by the high temperatures. It is essential for ship safety that cryogenic valves that are set to be installed on LNG carriers are truly fire-safe, as any leakage of gas from a valve in the event of a fire could lead to a catastrophic explosion on board a vessel.
Chris Hey, lead test engineer at Bestobell Marine, explains: 'We have seen in recent years what appears to be a lowering in standards by the class societies which appear to be approving cryogenic valves for installation on ships that are not fully fire-safe, especially for LNG fuel gas systems. BBM has always designed cryogenic valves to be fire-safe and we will continue to push the industry to adopt the highest standards to maintain the immaculate safety record on board LNG carriers.'
In the SIGTTO guidelines for the selection and testing of cryogenic valves for ships, it states that cryogenic valves should be of a 'fire-safe' design to an applicable standard, such as BS6755 Part 2, or equivalent.