The safety distances to be applied for LNG fueling and bunker operations are critically influenced by gross failure (rupture) of transfer hoses or loading arms. This project aims to prove that for small scale LNG composite hose based transfer systems a full bore rupture scenario is much too conservative for existing technology and that much less LNG outflow can be substantiated. This on its turn allows a reduction of the necessary safety distances around LNG service facilities.
A first series of experiments was conducted earlier as described in the TNO report 2015 R 10689 (see sub-activity Leak before Burst – phase I). Here some first fatigue tests were done with a longitudinal cyclic stretching of the composite hose. In this sub-activity (phase II) further fatigue experiments were executed to get a better understanding of the hose behavior under normal conditions while in use for example at a re-fueling station.
Next to longitudinal stretching, a composite hose was fatigue loaded through bending while being pressurized to 2 bar and cooled down by LIN/GAN. At this point in time leakage developed and subsequently pressure testing of the hose was done under conditions well above operating pressure.
It is clearly demonstrated that for the composite hoses tested:
- fatigue damage is (likely) detectable,
- full bore rupture is not expected and
- the resulting release of product (LNG/NG) will be insignificant compared to full bore rupture.
It therefore is reasonable to conclude that fatigue damage to a composite hose will lead first to a leakage that will very likely being detected under normal operating conditions and full hose rupture will not occur under these circumstances.