Thread Content
In winter, especially in the northern regions, as temperatures drop, when the medium to be measured is conveyed through the measurement pipeline to the transmitter, phenomena such as freezing, solidification, and crystal formation can occur due to the excessively low ambient temperature. This low temperature exceeds the normal operating range of the instruments used, thereby affecting the accuracy of the measurements displayed by those instruments. For various instrument points such as those for pressure, flow rate, liquid level, and temperature, the medium being measured is usually a liquid; exposure to low temperatures can lead to measurement errors, and in severe cases, it may cause safety incidents such as poisoning, fires, and explosions. Therefore, every year when winter arrives, it is particularly important to take measures to protect instruments and equipment from cold and freezing conditions. Some large-scale users of instruments and meters have taken early measures to prepare for this situation; for example, power plants, oil industries, chemical plants, water treatment facilities, and others have established systems suitable for protecting their equipment from cold and freezing conditions, and they carry out various tasks such as preventing freezing and cleaning the instruments. Here, Beijing Hengtaifengke Testing Equipment Co., Ltd., drawing on its many years of production experience, will discuss with you how instrument users can take measures to protect instruments from cold and freezing in winter. Moreover, many construction sites and builders choose to continue working during winter, but construction in winter takes place in many locations and involves numerous risk factors, making safety tasks extremely challenging. Additionally, winter weather is dry, with frequent wind and snow, which is unfavorable for construction work. In response to these situations, a series of necessary safety measures are taken to ensure the personal safety of construction workers and the normal operation of instruments and equipment during winter. Anti-freezing measures in the power sector: (1) The sector improves its cold and freeze prevention systems, and conducts regular inspections to ensure their proper implementation. (II) During the autumn safety inspection, special attention should be paid to implementing protective measures for key areas prone to cold and freezing conditions. (III) Relevant specialties shall formulate and strictly implement anti-cold and anti-freezing measures for soot blowing systems, drain pipelines, and sampling pipelines to ensure the safe operation of equipment during winter. (IV) Strengthen the management of the soot blowing system to ensure the normal operation of equipment in winter ； Personnel should be assigned to carry out pre-operational inspections of the system, to eliminate defects promptly and ensure that the equipment can be put into use properly. (5) Inspect all drain pipelines, sampling pipelines, and main steam pipelines of the soot blowing system to ensure that there is no peeling or exposure of the insulation; any damage to the insulation found should be repaired promptly. (VI) Provide heat tracing for the relevant pipelines in a timely manner according to temperature changes. (7) In the event of pipeline leaks or damage to the water gates, the valves at each drainage point must be in good working condition to facilitate timely repair. If any defects exist, they should be addressed in advance. (8) Check whether all covers in the cable trench are present and intact, and whether the cable openings are properly sealed; if not, they should be sealed promptly. The holes and gaps left in the wall after maintenance should be sealed up promptly. (IX) Before winter arrives, insulation covers should be installed on all outdoor switch boxes; the power supply for all switches must be in good condition, and inspections should be intensified to ensure the proper operation of the equipment during winter. (10) The Operations Department requires personnel in all shifts and positions to ensure during inspections that doors and windows at the production site are properly closed and secured; any damaged doors or windows must be reported promptly ； So that arrangements can be made for processing. (11) When the temperature is below zero degrees Celsius, the on-duty operators must turn on and off the various oil pumps and water pumps at regular intervals ； In the event of a unit shutdown, the cooling water in the container pipes should be kept flowing as necessary, or the water should be drained completely. For boilers that have had water drained from them, the thermal engineering staff should be informed to drain all the water from the gauge tubes. (12) Temporary insulation measures should be taken for doors, windows, or openings that are left open during winter for maintenance purposes; once the maintenance is completed, they should be restored to their original state promptly. (13) All operators should develop practical accident scenarios based on seasonal changes and operating conditions; during shifts, they must strengthen the inspection and maintenance of equipment, and promptly contact the maintenance team to address any defects detected. (14) Each duty officer shall regularly check the heating systems, doors and windows, glass, as well as key areas in the production facilities under their responsibility by installing thermometers; any abnormalities detected must be reported to the relevant departments for handling promptly, and this should be included in the handover procedures as well as the routine equipment inspection tasks. (15) If equipment must be shut down due to defects, anti-freezing measures should be taken, and inspection frequency should be increased to ensure the safety of the equipment. (16) The Human Resources Department ensures that labor protection supplies are adequately prepared and distributed in a timely manner; if necessary, additional cold- and frost-protection supplies can be provided at any time. (17) The thermal engineering team checks the status of heating for all instruments in use within the thermal engineering system. (18) The boiler team is responsible for sealing the doors and windows in the boiler room, as well as installing heating equipment in areas at the boiler’s zero-level and in places with lower temperatures. (19) Heat the oil tanks and fuel pipelines, and strengthen inspections ； The auxiliary oil station promptly activates the electric heating for lubricating oil according to weather conditions. (20) In case of rain or snow, personnel at all levels should take care to protect themselves while conducting inspections and operations to avoid slipping and getting injured. (21) All operations carried out by personnel at all levels to prevent cold and freezing conditions must be recorded in detail. Regarding anti-freezing measures in chemical plants: (1) Ensure proper personal protection by wearing warm clothing, and take precautions to prevent slipping when moving up and down the towers during inspections. (II) Strengthen dehydration efforts to promptly remove moisture from all dehydration points and prevent freezing blockages. (III) Pay attention to the level gauges in use; if the angle valves at the top and bottom of such gauges freeze up, it will affect the accurate measurement of the liquid level. If the transmitter associated with the level gauge freezes up, it will impact mechanical rotation and current flow, thereby affecting the accurate measurement of the liquid level. (IV) The temperature of the circulating water should not be allowed to drop too low; it must remain above 8 degrees. If it falls below 8 degrees, freezing and blockages in the cooler’s auxiliary lines can occur, and in severe cases, the pipes may even crack. (5) Insulate the pipes in the stagnant water areas of the workshop’s circulating water system ； The decommissioned circulating water pump was subjected to reverse flow measures and its contents were completely drained. (VI) For equipment that is not in use in the workshop, such as make-up water pumps, circulating water pumps, coolers, condensers, etc., measures like draining water and regular inspections must be taken. Compressor cooling water is regularly checked by operators to ensure that the water valve remains open at all times. (7) If a liquid hydrocarbon pipeline becomes frozen and blocked, be careful of physical explosions when using steam to clear the pipeline; do not force the cleaning process, rather preheat it gradually. (8) On-site pressure gauges can also give false readings in cases of freezing and blockage; judgment should be based on experience. Any uncertainty should be reported promptly for handling. (IX) When purging pipelines frozen and blocked, use steam to purge the elbows. (10) Pay attention to enhanced liquid removal from gas pipelines to prevent liquids from entering the boiler. Check the natural gas lines to prevent blockages caused by frozen crystal structures. (11) Strengthen inspections to monitor the temperature at each point. (12) The water supply pipeline should be kept from being completely closed to maintain a continuous flow of water. (13) For decommissioned equipment, blind flanges should be installed at the connections to the production system, any accumulated water should be drained, and the area should be purged thoroughly. For equipment left outdoors and those without covers, take measures to prevent water, snow, and ice from accumulating and damaging the equipment. For outdoor equipment, the frequency of routine inspections and gear turning must be increased. (14) For equipment used in production and daily operations, as well as those that are temporarily out of use, steam pipelines, and control valves must be equipped with anti-freezing and insulation measures. Any water stored within them should be drained, or a system should be employed to maintain a steady flow of water or steam in small amounts, thereby achieving both anti-freezing effects and water/speed savings. After the supply of water and steam is stopped, the systems must be thoroughly flushed. (15) Strengthen routine inspections for dehydration; check for dehydration at the lowest points of various equipment and pipelines. The cooling water supply to pumps must not be interrupted, and heating systems must remain functional. Pressure gauges and level gauges should be checked regularly, while steam and water hose connections as well as other related components must ensure continuous steam output and flow of water. Insulation measures for preventing freezing of instruments and meters: 1. Use insulation materials to provide protection, that is, wrap the parts of the instruments and meters that are prone to freezing with such materials. When winter arrives, inspections should be carried out and waste should be removed regularly to prevent damage to the insulation material of the packaging. 2. Heating measures: Steam heating measure – that is, using pipe steam for heating and insulation. Before supplying steam for winter insulation, check whether the steam insulation piping is unobstructed or blocked. Ideally, the steam should be supplied continuously for 24 hours at a moderate temperature. Sometimes, it’s necessary to adjust the amount of steam used for insulation according to changes in weather and temperature. This prevents two situations: when excessively high temperatures cause the condensate in the transmitter’s pressure piping to vaporize, thereby affecting its operation; or when excessively low temperatures cause the condensate to freeze, also disrupting the normal functioning of the transmitter. 3. Measures for the thermal insulation protection box: a) The electric heating tube type thermal insulation box consists of three main components: the box body, the heater, and the instrument holder. Its structural design is similar to that of a regular protection box; the difference lies in the presence of an electrical heating device inside the box. This heating device is made up of electric heating tubes and a temperature controller. There are sockets on the sides of the box body, and once power is supplied, the temperature inside the box rises to the desired level. Once that temperature is reached, the temperature controller continues to supply power to keep the temperature high. Repetitive operation is used to keep the temperature inside the box within a certain range. The main parameters of its constant-temperature heater are: (1) Rated voltage of 200V. 50Hz ； ⑵, rated power 300–500W ； ⑶The control temperature can be set by the user ； ⑷Constant-temperature heaters can also be made explosion-proof ； ⑸There are three types of materials for electric heating tubes: copper tubes, carbon steel tubes, and stainless steel tubes. b. Steam pipe heat tracing insulation box, the heat tracing tube is made of a metal tube in an S-shaped structure. The top and bottom of the box are welded together using welded plate joints with the heat tracing tubes; these tubes are installed inside the box with steam entering from the top and exiting from the bottom, and heating is achieved through the circulation of steam within the tube chambers. Heating tube materials are generally divided into two types: copper tubes and seamless steel tubes (carbon steel). c. Adding another layer of insulation foam to the key instrument cabinets, and sealing the openings of these cabinets as well as the inlet and outlet pipelines with glue, can achieve a better insulation and anti-freezing effect for the instrumentation system.