Degenerated High-Energy Piping Supports of Thermal Power Plants

Abstract

High-energy piping systems of power plants, such as Main Steam (MS) pipes or Hot Reheat (HR) pipes, operate at high temperatures and high pressure at base and cyclic loads. In the event of transient conditions, a pipe can be deflected dramatically and cause high stress in the pipe, leading to the failure of the piping system. Pipe hangers/supports are vital in maintaining the forces and stresses of the piping system within the allowable limits by allowing sufficient pipe movement from cold to hot conditions and protecting the piping system from operation transient loads such as steam hammer and water hammer events. Thus, the pipe hangers and supports shall be inspected regularly to ensure their functionality. This paper presents examples of common issues found in degenerated pipe hangers/supports in power plants. The pipe support site inspection generally found deviations in pipe travel, which were not as expected by design. Design reviews have shown that the design travel of pipe support can differ from those found on pipe support nameplates, and the deviation can be as much as 74%. The actual load of pipe support can deviate as much as 18% from the design load and requires rectification as undesirable high stresses can be developed over time if it is left unattended. Pipe hanger/support inspection data can be used in further assessment, such as piping structural analysis. Deteriorated or degenerated pipe supports shall be identified, prioritised for further assessment, and monitored regularly as part of a strategy and initiative to ensure total plant safety management, with the aim to minimise the risk of premature and catastrophic failures.

Keywords

• degenerated
• inspection
• pipe hanger/support
• piping systems
• power plant
• walk-down