Joints with cotter pins have, over the years, served in applications where simplicity, rapid assembly, and disassembly were of importance. Typical areas of use in the past included piston rod connections, engine crossheads for steam and internal combustion engines, as well as special elements of tool fixtures. The theory of elastic interference, however, should apply to all types of threaded connections utilized in pipe coupling design. The magnitude of the actual clearance, and its effect on the eyebar joint design, appears to be rather poorly defined in design literature because of the theoretical complexity of the problem involved. Joint technology in high-pressure closures usually involves bolts holding down the closure or a conventional threaded nut acting as the closure itself. The threaded-coupling connections must be designed for correct make-up torque and minimum leakage. The development of high-pressure closures in modern industry has involved significant research into the distribution of loads and stresses in large threaded connections.