As winter weather approaches, operators and plant management must remain vigilant in preventing freezing of their equipment. Frozen piping systems can result in ruptures and leaks that have devastating consequences, costly downtime, and unplanned outages.
There are many piping systems used to transport water or other liquids that are exposed to cold weather at most plants. They may be directly exposed to the weather by being located outside, or in some cases, they are installed in areas of the plant that are not heated. If the weather becomes cold enough, the contents of those pipes containing water or other liquids may freeze and expand, which can cause the pipes to burst. Depending on the system, a ruptured pipe may force the entire plant to be shut down. Steps should be taken to ensure equipment is not damaged during cold weather through the use of:
- Freeze Protection Valves
- Freeze protection valves are installed on systems to drain or bleed water as temperatures approach freezing. Ice will still form on the inside of the system piping where these valves are used; however, they prevent the piping from rupturing.
- Continuous Flow
- Having flow through a piping system assists with preventing the process fluid from freezing. Situations, where fluid is stagnant and exposed to extremely cold conditions, should be avoided.
- Piping Insulation
- Insulation is used to prevent freezing of various liquid piping systems by minimizing the heat transfer from the system to the environment. Insulation will not prevent freezing by itself but does make systems more efficient when used along with other forms of freeze protection.
- Glycol Concentration
- Glycol additives in system process fluids are another form of freeze protection. Keeping a concentration of Glycol in the systems will lower the freezing temperature of the process fluid, which allows the system to operate at a much lower temperature than it could otherwise.
- Electric Heat Tracing Systems
- Electric heat tracing systems consist of a heating cable fixed along the length of the system piping. The heating cables ensure that fluid contained within the piping never freezes, while also ensuring that the heating cable does not become hot enough to catch the insulation on fire.
- Steam Heat Tracing Systems
- Steam heat tracing systems usually consist of a piping system that is laid alongside piping and equipment inside insulation. Steam passes through the piping system and around the piping and equipment to warm the process fluid, keeping it in a liquid state during cold weather conditions. Steam Heat Tracing Systems are typically used for freeze protection on systems with very large piping or in very long runs.
Operators and management must ensure that whatever means of freeze protection they have available to them are prepared for operations before it is too late. Failure to ensure these systems are properly aligned and placed in service can have catastrophic consequences. One way to ensure these systems are operated and brought online properly is through the use of detailed operations and maintenance procedures.