In most piping systems, there is a need for backflow prevention. Most piping systems utilize pumps or compressors to generate needed pressure for movement of line fluids or gases. When rotating equipment stops, flow reversal or backflow occurs, and one of the most significant elements of the LNG production system design is integrating kp-lok.com the means to prevent backflow, thereby protecting equipment, and avoiding damage to plant infrastructure, as well as excessive emission leakage, and potential medical emergencies. Whether in the gas field, liquefaction plant, LNG storage tank, LNG tanker or gasification terminal, a valve that is paramount across the LNG value chain is the check valve. These valves offer solutions to the destructive effects of flow reversal and prove reliable in the severe conditions presented during the LNG process.
Liquefied natural gas (LNG) is natural gas cooled to -260° Fahrenheit (-162°C) until it became a liquid and stored at substantially atmospheric pressure. Converting natural gas to LNG, reduces its volume by about 600 times, allowing it to be transported internationally. Once delivered to its destination, the LNG is warmed back into its original gaseous state to be used as existing natural gas supplies, by sending it through pipelines to its customers. LNG is used in residential, commercial and industrial markets for a variety of purposes such as for cooling and heating homes, cooking and other industrial energy supplies for electricity generation, manufacturing of paper, glass, metal, etc. Also, LNG is increasingly used to fuel heavy-duty vehicles; imagine that this process requires a lot of valves.
Valves provide the answer to the unfavorable effects of flow reversal and are reliable in the harsh conditions experienced during the process of LNG production. Valves are designed, primarily, for protecting piping systems equipment such as pumps, compressors, or other critical components along the value chain from accidental damage due to dangerous system deceleration and water hammer. Different valves function as prescribed but are mainly designed to prevent damage and support the system to work efficiently.
The check valve, for instance, is not the same as shut-off and control valves. It has backflow capacity with the ability to stop the flow altogether, or allow fluid to flow in a single direction and prevent surges! Additionally, they are flow-sensitive causing the line fluid to open and close. This action makes Check valves one of the few self-automated valves around.
Because LNG is cooled to such low temperatures, valves used in the LNG industry must meet cryogenic temperatures of -168°C to -198°C. The development, transportation, and receiving of LNG requires valves, and with the market for LNG expanding, the challenge of many valve manufacturers is to develop their product ranges to offer valves constructed of quality cast and forged materials. The performance and reliability of the valves are vital to the whole process, and this can only be achieved through critical design, manufacturing, and material selection. However, besides API 598 cryogenic valves have to meet BS 6364, which is tested with helium at -270°F (-168°C) to -325°F (198°C). A major challenge for current valve manufacturers is to not only remain competitive in this relatively new and growing market but also maintaining and improving quality and performance.
To address LNG challenges, manufacturers need to seek out alternative check valve solutions that incorporate features and benefits that can directly address and counter these problems. For example, a dual-plate wafer valve design is a stronger, lighter, smaller and more efficient check valve than the swing check. Utilizing springs to increase the valve reaction and response time, a highly engineered dual-plate check valve can better protect equipment in place along the liquefaction, and regasification terminals present within an LNG processing plant.
Increased response time can reduce the water hammer effect for an improved non-slam performance. Directly addressing the extreme cryogenic demands of the liquefaction process, certain dual plate check valves have been approved for subatmospheric to cryogenic temperatures ranging from -58°F through -321°F.