With the exhaustion of petroleum resources and the intensification of environmental protection, liquefied natural gas (LNG) has become a new type of ship power fuel. LNG is obtained by liquefaction of gaseous natural gas at ultra-low temperature (-162℃) under normal pressure. Compared with traditional diesel fuel, LNG has become a vital fuel to be gradually promoted and used because of its low price, high calorific value, and low pollution.
Natural gas is colorless, odorless, flammable, and explosive. Pipeline as its transport carrier, if the failure will lead to media leakage, or even explosion, resulting in huge losses and even casualties, so the pipeline as one of the special equipment must be designed, manufactured, used and managed in accordance with the specifications, to ensure that its strength can meet the requirements.
In the process of manufacture, construction, and operation, defects inevitably occur in pressure pipelines, leading to excessive local stress, which will affect the service life of pipelines. Therefore, it is more important to calculate the stress of pressure pipeline under the combined action of internal pressure and local load. For pipelines’ safety, countries to develop various standard reference for engineers to calculate, such as ASME, RCCM, EN13480 etc. These standards are the conventional structure provides a good design method, however, does not provide a theoretical basis for special structure, in order to meet the needs of the production process, equipment, pipeline structure tend to become complicated, such as the diversity of the external load at the same time, lead to the conventional calculation does not demand.
Finite element method is a numerical approximate solution method, which is a supplement to the exact solution method of analytical formula. Due to the complexity of engineering problems and the limitation of solving theoretical solutions, the finite element method is popularized. It has the advantages of wide applicability, reliable calculation and so on. It plays an irreplaceable role in providing product design quality, shortening design cycle and reducing product development cost. After more than half a century of development and practical engineering application, this method has been proved to be an effective calculation method.
With the development of The Times, the calculation methods are constantly updated. Under the condition of using the conventional design methods in the standard to ensure the pipeline’s safety, the finite element method has also become an indispensable calculation method, which provides a guarantee for the safe operation of the pipeline.