A History of the Target Torque Values From ASME PCC-1 and Future Direction

Since its original issue in 2000, ASME PCC-1 has provided guidance to the user for establishing target torque values for bolted flanged joint assembly. The original tables were developed based on a reference bolt stress of 50 ksi (345 MPa) with guidance provided for making adjustments using other bolt stress values. Despite its attempts to provide clarity, the industry perception has been that the 50 ksi (345 MPa) reference bolt stress is a mandatory requirement, which has never been the intent. This paper reviews the basis of the original Table 1M/Table 1 values provided in PCC-1, and provides a forecast of future improvements utilizing a new concept called a Target Torque Index based on a unit bolt stress, allowing the user to utilize the guidance in Appendix O of PCC-1 to define the appropriate bolt stress for their particular situation.