Main Steam, Hot Reheat, and Cold Reheat piping represent critical systems which can be subject to catastrophic failures. These lines transport steam to and from the boiler and turbine. The pipe leads range up to several hundred feet in length and may be as much as over 5″ thick. The loads on some hangers can be as large as 150,000 pounds. Thermal movements of as much as 12″ are common. These lines and supports must receive the necessary attention and service to insure the safety of the critical high pressure piping systems.
In the past, the conditions of the pipe supports were largely ignored. Being engineered products, hangers are designed to withstand many loads and abnormal operating conditions. Standard practice is to design for twice the rated load, and in some cases, five times. As a result, the supports rarely reflect problems by breaking or falling down. Usually, only through periodic inspections or surveillance can most problems be identified and steps taken to correct or solve them.
On many power plant installations where the critical piping systems have been walked along their entire length and the pipe supports have been inspected, the pipe supports were noted to have been frozen in a topped or bottomed out position. In many supports, failures had occurred in the springs, clamps, hanger rods, and other related hanger components.
The following is a brief outline of a program that should be implemented at all generating stations. Further implementation details will be provided upon request.