Experimental investigation of the movement patterns and deformation of the pigs when passing through a pipe elbow and reducer
Authors: Stetsiuk S.M. , Doroshenko Ya.V. , Doroshenko Yu.I. , Filipchuk O.O. , Grudz V.Ya. 
Published: October 2024

Experimentally investigate the movement dynamics of the pigs having various geometric shapes through the pipeline elbows and adapters manufactured from various hyperelastic materials, and assess the risks of their getting stuck in such elements. Experimentally determine the required pressure in the behind-pig space for the experimental pig prototypes to pass through the pipeline elbows and adapters.Pig prototypes of various geometric shapes (cup-type, cylindrical two-disc type, multi-disc type, dumbbell disc type and three-ball dumbbell type) were designed in order to carry out the experimental investigation. Based on pigs' 3D models, the 3D models of casting mould have been designed and printed on a 3D printer. Pig prototypes were manufactured by filling the casting moulds with silicone compound with hardness of 30 units by Shore A hardness scale and polyurethane with hardness of 80 units by Shore A hardness scale.An experimental glass pipeline was designed and mounted to monitor the dynamics of the solid-cast pig prototype movement through the pipeline elbows. Video recordings of the process allowed us to identify and describe the patterns of pig prototype deformations in the glass pipeline elbow. Pressure was measured in the behind-pig space during the movement of pig prototypes through straight sections, the elbow and the adapter of the experimental pipeline made of metal. Measurements were taken for dry and wet inner walls of glass and metal pipelines.Cup-type pigs made of silicone compound showed best results in passing through the elbows at the lowest pressure in the behind-pig space (0.33 kgf/cm2). However, suppose the inner wall of the pipeline is dry. In that case, the pig tightness is lost in the pipeline elbow due to significant deformation of the pig, which causes the behind-pig space pressure to increase to 0.71 kgf/cm2 and augments the risk of the pig getting stuck. The dumbbell disc-type and three-ball dumbbell-type pigs made of silicone compound also show good results in passing through the elbows with low pressure in the behind-pig space (up to 0.5 kgf/cm2). Polyurethanepigs are highly rigid; therefore, for them to pass through the pipeline elbows, the pressure in the behind-pig space should be 2-4 times higher than for pigs made of silicone compound.Only the cup-type pig made of silicone compound can pass through the reducing pipe adapters with pressure in the behind-pig space being at least 8 kgf/cm2.The investigation was performed in experimental mode. Further investigation will entail mathematical and numerical modelling of the pig prototypes movement through the pipeline elbows and adapters.The results obtained during the investigation will help to develop a more thorough approach to planning the process of using the pigs to clean the pipelines with elbows and reduce adapters. They allow us to choose the geometric shape and material of the pigs, taking into account the pipeline operating parameters (inlet pressure and flow rate). It is especially appropriate during the first planned pipeline cleaning with pigs. It allows us to minimize the risk of pigs getting stuck in the pipeline.The subject of investigation is patterns of the pig`s friction coefficient, material hardness and geometric shape, impacting its ability to pass through the elbows and reducing adapters, and the value of the required pressure in the behind-pig space.