Winter anti-freezing
Thread Content
As winter approaches, how should pipes, equipment, and valves on-site be protected from freezing, and which parts need such protection? What are the anti-freezing measures? (1) The anti-freezing protection design should be based on the average temperature of the coldest month in the atmosphere. (2) In pipeline design, fluid circulation within the system should be utilized as much as possible to prevent freezing, thereby avoiding the need for heating. For example, in a cooling water system, when the equipment is shut down, a bypass near the heat exchanger can be used to enable the circulation of supply and return water. In the design of fluid flow pipelines, dead corners where freezing may occur should be avoided. For unavoidable dead zones, insulation and heat tracing should be used to prevent freezing. Pipelines with no fluid flow or those that are used intermittently should be avoided as much as possible; if such pipelines are unavoidable, insulation and heat tracing should be considered in the design. (3) To prevent freezing through proper drainage, for utility pipelines such as water, condensate, and steam, liquid accumulation and freezing may occur during shutdown; therefore, appropriate drainage, venting, and self-drainage mechanisms should be considered in the design. During periods of inactivity, these pipelines should be completely drained. (4) Underground pipelines and their drainage systems should be buried below the permafrost layer. The main pipes for fire water, drinking water, utility water, and cooling water shall be laid underground. (5) Anti-freezing measures for the main supply and return water pipes: Circulating bypass pipelines are installed between the main supply and return water pipes as well as between the endpoints of these pipes. For branch pipes leading off from the main pipe, a shut-off valve should be installed at the high point of the horizontal section near the main pipe. The length between the cut-off valve and the main pipe should be as short as possible. (6) For containers used to handle hydrocarbons and water, the pipe openings, isolation valves, and drain lines that are in contact with water should be equipped with heating and insulation measures to prevent freezing ； For heat exchangers and coolers that handle fluids that may freeze, sufficient drain ports equipped with valves should be provided to ensure that the equipment is completely drained during shutdown ； The water cooling system on the pump or compressor should be equipped with sufficient drain points equipped with valves, to ensure that the system can be completely drained when it is shut down. (7) For pipelines that require anti-freezing protection, steam tracing and insulation should be used. The heating medium should be low-pressure steam, with a drain installed at the lowest point. All pipelines should, as much as possible, be designed for self-drainage, and the steam in the heat tracing pipes should flow downward. Each heat tracing unit shall be equipped with a ** steam supply valve and a drain. Slightly open the cooling water line of the pump, and drain the water from within the pump body of the standby pump. Valves that cannot be switched manually should not be forced to be switched; pumps that will not rotate should not be started ； Drain condensate regularly at the lowest point of the instrument air line to prevent water from entering the instrument air. Conduct a thorough inspection of the instrument pipelines related to steam, ensure proper drainage at the lowest points, and work together with the instrument technicians to verify that the heating pipelines are unobstructed. Fresh water and domestic water supply will be discontinued, and any water remaining in the pipelines must be drained completely. Ensure a constant low-flow of water at the high and low points of the piping to prevent condensation in the pipes. Strengthen management by establishing records for anti-freezing and anti-condensation measures (including accident logging, the condition of anti-freezing and anti-condensation equipment, and pipelines prone to freezing). Strengthen winter patrol inspections; focusing on the anti-freezing checks of pipelines, pumps, and instruments. While ensuring energy conservation and emission reduction, it is necessary to prevent water accumulation, freezing, ice formation, or frost in the plant area. Common methods used in practice include: heat tracing, evacuation, and purging. Of course, if conditions permit, the system can be kept operating continuously, or temporary indoor pipelines can be used.
Antifreezing measures also vary by region; there is a significant difference between the north and the south
The poster is in Inner Mongolia; the winter weather outside the Great Wall is extremely cold, so it’s important to use antifreeze and anti-condensation agents. In our Central Plains region, we also face difficulties with this kind of work in winter
The shutdown device should be drained and cleaned.
The weather in Hebei is causing problems with antifreeze!
Key points for freeze protection in winter: When operating in winter, the main concern is preventing equipment and pipelines from expanding due to the low temperatures around them, which could lead to production disruptions and malfunctions of control devices. To address this, the following points should be taken into account: 1. Install insulation boxes for instruments in areas where it is necessary. 2. Identify the dead ends in the pipeline and take measures to prevent freezing and cracking. 3. Use insulation materials to enhance the device’s insulation. 4. Carefully monitor the operation of the equipment to prevent freezing in pipes and equipment, and take measures in areas where freezing is likely to occur. 5. Strictly prevent leaks in equipment and pipelines, as freezing is likely to occur at the leakage points, affecting the normal operation of the system. 6. In the event of a stoppage or accident, as long as the entire system has not been completely shut off and water has not been fully drained from the system, steam supply must be maintained. 7. Some pipelines without heating may freeze during shutdown; therefore, all liquids and water must be drained within half an hour after shutdown, taking care to handle the disposal of toxic liquids. 8. When the surrounding air temperature is below zero degrees, the heating of the equipment and pipelines must increase by 25°C per hour once the device starts operating; at this time, the temperature difference between the inlet and outlet of the equipment should not exceed 100°C. 9. When pressurizing the device during startup, the pressure must be increased gradually – 0.25 times the operating pressure can be applied in the first hour, with an additional 0.25 times the operating pressure added every 15 minutes. It is crucial not to increase the pressure too quickly.