TopFasterner logo provide constant spring hanger, usually referred to as a constant, provides constant support force for pipes and equipment subjected to vertical movement due to thermal expansion at locations where maintaining a constant stress is critical. This constant resistance is achieved by having two-moment arms pivoted about a common point. The load is suspended from one of these arms, and a spring is attached to the other. With an appropriate choice of moment arms and spring properties, a resisting force can be provided that is nearly independent of position. As with variable springs, Type refers to the connection of the constant to the structure and the pipe. Figure 1 shows the attachment for Types A – E.

Travel stops are installed in all constants before shipping. These must be present during installation and any hydro testing, but must be removed before normal operations. They are usually pins, but in some cases may be keys. See note below on travel key removal. In either case, the load must be adjusted so that the travel stop is easily removed.