LAUSR

A cryogenic triple-offset butterfly valve, which is installed in LNG marine engine, controls flow of liquid nitrogen (− 196 °C) to liquefy natural gas (− 163 °C). The existing seal has dual-layer structure composed of rubber and metal seals. The rubber seal is needed to be frequently replaced owing to its low durability, and elasticity of the metal seal decreases in the cryogenic environment, so that leakage of the nitrogen occurs. In order to offer a combination of compressible and resilient materials that form a strong sealing performance in the cryogenic environment (− 196 °C), a new type of seal was devised by laminating muti-layers (graphite and stainless steel). The airtightness of the laminated seal was estimated by comparing contact pressure that occurs on surface of the seal with working pressure. Effects of design parameters in relation to the laminated seal were analyzed to improve sealing performance, and after that a shape of laminated seal to improve operability and airtightness was suggested. Also, the proposed model obtained from FEA was verified through hydraulic and cryogenic leakage tests.