The multi-scale finite element simulation method was used to study the sealing characteristics of pipeline fittings. Based on the measured data of rough surfaces

the multi-scale model of pipeline fittings was modelled

sealing state and sealing performance of fittings were obtained by simulating the tightening process of fittings. The results showed that the calculation results based on the multi-scale model could really present seal characteristics of pipeline fittings

and improve the calculation accuracy of pipeline fittings assembly method. In addition

during the process of fittings tightening

thehigh stress zone between pipeline fittings and ferrule diffused to all sides through two high stress zones

and the change of sealing performance of pipeline fittings presented linear change. When the displacement of ferrule reached certain position

the pipeline fittings achieved the optimal assembly state

making it particularly important for the application of pipeline fittings. Besides

the fluid temperature in the allowable range had certain influence on the sealing characteristics of pipeline fittings.