LNG Integral Safety Program

LNG Integral Safety Program

Publieke samenvatting / Public summary

Summary:

The increasing use of liquified natural gas (LNG) to fuel trucks and vessels will leadto more storage and transfer in urban areas. However, current safety distancesfor LNG fuelling and bunker operations are based on failure scenarios and occurrenceprobabilities that are largely determined by the gross failure (rupture) oftransfer hoses and loading arms. These distances limit the deployment of asmall-scale LNG distribution system. This project proved that, for small-scaleLNG transfer systems, the full bore rupture scenario is much too conservative.

 

Background:

This project was executed in two phases. In the first, it was proven that, forseveral hoses, two incident scenarios do not necessarily result in a full-borerupture. These results were reported in TNO report 2015 R 10689. It was then decidedto strengthen these results by conducting additional tests in a second phase.This report documents the results of that second phase. The project was carriedout on behalf of the LNG Safety Platform of stakeholders in the small-scale LNGsupply chain.

 

Projectobjective:

The approach was to prove that there are credible failure scenarios that, whilethey may result in leakage, do not lead to a full-bore rupture. The authors hopedthat authorities, based on the project results, would update their QRAcalculation procedures with specific leak scenarios.

 

Projectresults:

The firstphase of the project found that the fatigue failure of a composite hose maycause leakage. However, it also found that this would not necessarily lead to afull-bore rupture. In phase 2, four composite hoses were fatigue loaded untilserver leakage was present. This test found that the residual burst strength ofthese fatigued hoses appears to be higher than the maximum operating pressureof a small-scale LNG system. From this it is possible to conclude that while significantfatigue damage to a hose will cause leakage, this is likely to be detected wheneverthe remaining pressure capacity is higher than the maximum operating pressuresof the system. In other words, it is possible to prove that operators will beable to detect a leak in a particular multi-composite hose under normalconditions and before a full-bore burst occurs.

This finding covers the two potential critical failure scenarios that were investigated(crushing and fatigue), while normal conditions means where the residualpressure resistance is higher than the normal operating pressures (10 to 18barg). The report recommends further testing of different types of hoses andscenarios, plus the standardisation of tests.