Winter Anti-freezing and Anti-condensation Plan for Instrument Workshop

Anti-freezing and Anti-condensation Measures

Proper Selection

When selecting instruments, full consideration should be given to their anti-freezing and anti-condensation performance. Instruments with thermal insulation and tracing, as well as isolation tanks, should be chosen based on working conditions and media. Appropriate tracing methods such as steam tracing, electric tracing, or hot water tracing should be selected according to on-site conditions and explosion-proof requirements. Signal remote transmission instruments and display gauges must meet low-temperature resistance requirements, and the anti-freezing isolation fluid used should also be resistant to low temperatures.

Rational Installation

• Select the installation location reasonably to facilitate operation and maintenance. Install instruments in dry places free from rain and snow dripping as much as possible.
• The pressure guiding pipes of instruments should be reasonably arranged, as short as possible to avoid redundancy and reduce the risk of freezing and blockage.
• Tracing facilities should be easy to operate to ensure the smooth flow of steam pipelines or electric tracing circuits. When using thermal insulation protection boxes, different types and materials can be selected according to needs.

Key Parts

• Pressure/differential pressure/flow instruments with pressure guiding pipes for measuring steam, water, and media that may contain water; glass plate/tube, float, magnetic flap, and double-flange level gauges; as well as analytical instruments with pressure tapping pipes.
• Instrument air supply system, instrument air pipelines, and filter regulators of control valves and shut-off valves.
• Out-of-service instrument equipment.

Technical Measures

• Thermal Insulation Measures: Wrap easily frozen parts such as instrument pressure guiding pipes with thermal insulation materials like rock wool, aluminum silicate, or asbestos rope, and cover the outside with aluminum sheet or glass fiber cloth if necessary. For large spaces, transmitters can be installed in thermal insulation boxes with tracing.
• Adding Anti-freezing Fluid: Timely replace and add anti-freezing fluid to instruments equipped with isolation tanks. The service life of anti-freezing fluid is generally one year.
• Tracing Inspection: Regularly check the sealing condition and internal temperature of instrument tracing boxes to ensure normal operation of tracing systems. For electric tracing, inspect the power supply circuit and temperature controller; for steam tracing, check the steam circuit, wrapping condition, and smoothness of return water. Timely start tracing (steam tracing or electric tracing), put steam traps into use, and ensure their normal operation.
• Drainage for Anti-freezing: Regularly drain water from the ends of instrument air pipelines and low points of U-bends to avoid air circuit freezing and blockage caused by accumulated water. Drain all water from out-of-service equipment; if water cannot be drained through root valves, disassemble, drain, and purge thoroughly. Keep the plug of pressure transmitters loose and the blowdown valve of pressure guiding pipes open.
• Regular Patrol Inspection: Team members should conduct regular patrol inspections according to inspection requirements and routes. Appropriately increase the frequency of inspections in extreme weather and keep detailed inspection records.

Key Inspection Contents:

① Check if the power switch of electric tracing is closed and if the power indicator is normal (observe the ammeter if available to see if it is normal).

② Check if the steam trap of the steam tracing system is working properly.

③ Open the thermal insulation box to check for normal operation.

④ Inspect the integrity of thermal insulation materials for any damage or loss.

⑤ Check if the opening degree of valves in tracing pipelines is reasonable.