Abstract
Piping isolation and gripping test plugs have been utilized for many years to evaluate and maintain the integrity of pipe and piping systems, yet accidents still occur resulting in damage to equipment, lost time, personnel injury, and death. Fluid processing often requires high temperatures and pressures. Some of the fluids present chemical hazards to personnel, the environment, and equipment. In order to ensure that this hazardous, but important work can take place as safely as possible, pipe plugs have been developed to help isolate, test, and validate the related systems and equipment for use. Over the last half century the petrochemical industry has increased the emphasis on safety. Recently, for example, the Post Construction Committee of the American Society of Mechanical Engineers has addressed many issues for safe pressure testing in the recommended practices of ASME PCC-2. While many of these improvements are on the procedural side, recently there has been a significant push in industry to improve the safety and limit the damage to the piping systems under test by improving the underlying technology.
What follows is an account of the developmental history of the technology, including how each successive innovation has made improvements as well as noting their limitations. The newest innovations represent a step change in reliability and safety for both personnel and equipment, some by making significant changes from previous gripping plug designs. It is of critical importance that those responsible for deciding which technology to use for their particular service and/or testing needs are aware of the inherent safety and reliability concerns with older gripping devices, which, in some cases, are still sold and used. These new developments have the potential to save money by reducing test preparation time, and reducing or eliminating the need for post-test repairs or removal of portions of the pipe damaged by the grippers. Responsible parties should be aware that new innovations now exist which could potentially save lives and reduce cost by decreasing the risk of serious accidents.
