Estimation of the Load Carrying Capacity of the Bellows Compensator for Gas Pipelines in the Areas of Mining Production

The stress state of pipelines in areas of mine production requires obligatory consideration the influence of ground displacements. In this case the rules for design pipelines include the additional actions, such as the wall thickness increasing or U-shaped compensators installation. The Ukrainian coal mining industry requires the expanding of mine production areas. It leads to the situation where old pipelines, which are not designed for such loads, could rupture due to ground displacements. The principle of “extinguish a fire” is applied in this case. It consists in applying of stress reduction actions before certain stage of mine production (so-called lava), such as digging out long sections, cutting and sanding, which require the involvement of significant human and material resources. But, in some cases, even the large-scale application of these actions does not lead to the stress reduction to the acceptable level (especially for pipelines of diameter less then 200mm). So, to solve this problem the implementation of bellow compensators (BC) is proposed. The present work consists of: • experimental investigations of BC which are carried out in order to obtain its bearing capacity and to validate its designed parameters guaranteed by the manufacturer; • simulation of the BC loading process using FEM with adjusting the way of contact modelling between the BC layers in such manner, to be best correlate with the results of experiments; • the application of obtained results for modelling of stress state of real pipelines in the areas of coal mine production. The results of experimental investigation of BC of DN100 is presented. Their include: hydrotest with axial displacements limitation; tension-compression cycles for different values of amplitude with simultaneously loading of the operating value of gas pipeline internal pressure; rupture pressure determination. Based on the experimental results, numerical modelling and specified domestic software for stress state assessment in pipelines the optimal locations and the required number of BCs is determined for buried gas pipelines. The results of presented works allowed us not only to implement the BCs to gas pipelines DN100 in areas of mine productions, but also the necessary experience for creation of larger diameters BCs is obtained.