The process of converting natural gas into a liquid form, producing liquid natural gas (LNG), has revolutionised the fuel transportation process. The gas is predominantly made of methane (CH4), but also contains some mixture of ethane (C2H6) and when converted to liquid allows non-pressurized storage environments, meaning it can be transported easily and safely. LNG currently occupies 1/600th the volume of natural gas in a gaseous state at standard temperatures and pressures; this demonstrates the massive efficiency for storage and transportation. However, LNG is incredibly flammable after vaporisation and pipework used to transport the fuel must be fully welded to a high degree of accuracy. LNG is currently used to supply locations by sea where pipeline access is not feasible nor economically favourable; it is also used widely throughout Asia to fuel large over-the-road trucks. However, the use of LNG has not been widely adopted within Europe. This article will discuss the benefits of LNG and the welding requirements required for transport and storage.
Liquifying gas on a large scale was initially used to extract helium to be used in British dirigibles during World War I. The process was refined in the 1930s in an effort to store energy to ease peak energy loads during cold winter periods. Large-scale natural-gas liquefaction can occur through two processes, the cascade process and the Linde process. The cascade process uses a sequence of gases to cool the natural gas, hence creating a ‘cascade’ cooling process. The Linde process passes the natural gas over a cold orifice until its core temperature reduces and causes the gas to liquefy. LNG is in the early stages of being used to fulfil the mainstream transport fuel demand, being tested in a variety of trucking, off-road, train and marine vehicles. However, there are known issues with the fuel tanks used to store LNG in these vehicles and the pipework used to transport the fuel to the engine.
Recent work by Orbital Fabrications has included improving the pipework used in haulage vehicles through the development of LNG dispensers. Pipework developed has been used in extensive field tests, requiring accurate welding which meets the flow and pressure requirements of the project. The pipework must also be thick to reduce the damage risk in low-speed collisions. However, the pipework must still be manufactured to the high dimensional tolerances required, which is often uncommon in thick wall schedule pipe. The pipework was put through rigorous field tests which exposed the system to shocks, vibrations, cyclic loadings and other stresses which replicate the conditions of the road. If you would like to read more about Orbital Fabrication’s liquid natural gas dispenser project, click here to visit our Projects page.
Orbital Fabrications is a market leader in orbital tube welding, high-tech fabrications and machining services based in St. Ives, Cambridge. With over 25 years’ of experience, the team of highly skilled welders at Orbital Fabrication specialise in orbital welding, manual welding and other specialist welding services. Since its establishment in 1998, Orbital Fabrications has delivered fabrication services to a range of sectors including the nuclear, pharmaceutical, medical and aerospace industries.
Orbital Fabrications makes continuous investment into the latest technology and staff training, allowing them to provide specialist welding services that meet the highest industry standards. Recent expansions of their facilities has allowed Orbital Fabrications to offer a range of cleanroom services.
For more information on any of Orbital Fabrication’s services, contact us here or call on 01480 464 066.