In these years, risk mitigation measures against the cryogenic spill hazard become one of the critical factors to ensure the level of safety in cryogenic liquid handling process plant, such as LNG liquefaction facility. The cryogenic risk mitigation can be achieved by spill control, welding connection instead of flange connection, and cryogenic spill protection insulation on the structure and equipment, etc. In the LNG liquefaction facility, cryogenic spill protection insulation is commonly applied for the critical area in combination with other risk mitigation measures. On the other hand, there is no recognized standard approach to define the extent of area which cryogenic spill protection insulation applied even if the installation of cryogenic spill protection insulation is high cost and have difficulties in construction phase.
This paper proposes the simplified method to define the extent of cryogenic spill hazard area supported by the experimental test and simulation. For the less congested area of the facility, point source approach is applied. Leak frequency is calculated per flange and credible leak hole size is defined. Then, the extent of brittle fracture hazard area due to cryogenic hydrocarbon spill is decided from each flange. For the congested area, generic source approach is applied. In these areas, all leak sources are counted around the equipment to define the leak frequency, and credible leak hole size is defined. Then, the extent of brittle fracture hazard area is defined from the equipment. The cryogenic spill hazard area is considered as the extent of the LNG liquid droplet travel distance because the cryogenic liquid contact on the structure will cause the brittle fracture hazard (Wet condition on the surface on the structure cause the significant temperature drop). Simulation and Experimental Test are conducted to determine the extent of hazard area against the leak hole size.