Glossary

Startup retorque is a controlled re-torque operation on a gasketed, bolted joint performed during equipment start-up/warm-up (i.e., after the joint has been assembled and the system is coming up in temperature and/or pressure). Its purpose is to restore bolt preload and gasket stress that can drop after initial tightening due to gasket relaxation, seating, embedment, and short-term creep, so the joint is more likely to remain leak-tight in service.

It is commonly described as running a circular pass around the flange at the same initial final torque value used for assembly (or a value adjusted per procedure), tightening until nuts turn as required by the method, and it is often associated with what used to be called “hot torque/hot torquing.” Guidance commonly places it in a moderate temperature window (often cited around 250°F to 450°F) and cautions against higher temperatures because friction/nut factor behavior can change, affecting torque accuracy and risk.

Startup retorque is related to—but different from—a relaxation pass, which is performed at ambient temperature after a dwell period to recover initial relaxation before the system is put into hot service. Startup retorque is also not the same as “live tightening” or “hot bolting” done as a maintenance activity in response to leakage; industry guidance treats those as separate, higher-risk operations requiring specific controls.