Supporting a riser: Some do's and dont's

There are many ways to hang the vertical runs (risers) of a high temperature steam piping system in a power plant, and they can be classified crudely as right, not quite right, or downright wrong. This paper first discusses typical riser supports found in power plants designed and built in the last 40 years. Then a discussion follows that covers some of the problems that turn up if the supports on hot vertical pipe are inappropriate for the operating conditions, such as pipe temperature and thermal expansion, weight, and transient loading. Such topics as creep elongation, load shifting on rigid rods, variable springs vs constant supports, riser clamps, elbow lugs, support trunnions, rollers and travelers are discussed. Conclusions and recommendations are presented to enable a designer to choose riser supports wisely and consider a proposed design in light of industry experience