Modified Pipe Connectors for High Pressure Pipe Joints

Abstract In high-pressure [excess to 100 bar pressure] piping circuits in a refinery, petrochemical plants, fertilizer plants, power plants, etc., piping ends are connected with flanges/bolts/gaskets designed as per ASME B31.3 which is a process piping code. ASME B16.5/B16.20 is one of the popular removable flanged/gasketed joint arrangements However, these gasketed joints tend to leak at high pressures. Therefore, many end users are forced to weld piping ends [Refer Figure 2]. However, welding of piping ends reduces the flexibility of maintaining piping system as the end user is required to cut the pipe / weld for maintenance / modification and then re-weld the pipe. This is a very cumbersome and time-consuming activity as it involves on site welding which is very skilled work followed by local post weld heat treatment, and non-destructive examinations such as Ultrasonic examination or Radiographic examination. Therefore, there is a need for a convenient and foolproof design of removable pipe connectors that can be used to connect two pipe ends easily and can be detached easily whenever required. Some plant operators are now using clamped pipe connectors with T-shaped metal seals as an alternative to conventional ring flanges. The work in this paper relates to an improved pipe connector design that involves a self-energized gasket combined with a blind cover, designed to work with the “Modified pipe connector” system. Additionally, it incorporates a mechanism that allows for online testing of the equipment without requiring its removal from the operational loop. The improved pipe connector, design incorporates a specially designed self-energized Y-shaped sealing ring [Gasket] that provides multi-stage sealing such that: - A first stage sealing is achieved by “when the clamp bolts are tightened, the hubs are drawn together by wedge action on the two clamps compressing the Y-shaped sealing ring. - A second stage sealing is achieved by increasing the sealing pressure between the seal and hub faces thereby reinforcing the seal. With the improved/modified pipe connector we aim to achieve a more reliable and leak tight joint. Extensive analysis has been carried out to substantiate the above and the results of the same have been included in this paper.