Cold storage engineering construction plan

Cold storage technology     Part 1
Cold storage engineering construction plan

Section 1, project content

The project content mainly includes: procurement of various cold storage engineering equipment and facilities, consumables and accessories, storage body installation, internal and external machine hoisting, laying connecting pipelines, pipeline insulation, drainage pipe installation, line erection Connection, control system installation, internal and external power line wiring and system debugging. The power supply required by the cold storage unit, that is, the cable entry is not included in this installation scope, and the cold storage and unit foundation are coordinated and constructed by civil engineering.
Section 2. Main construction methods and technical requirements
1. General procedures for installation engineering,
human organization, equipment entry, joint review of drawings and technical disclosure, material procurement approach, support bracket production, warehouse body splicing, partition wall perforation, and drainage pipeline installation , bracket installation, welding installation of main line, main line insulation, branch
pipe welding, pipeline insulation, control line laying, indoor unit fixation and interface, outdoor unit hanger fixation and interface, blowing, pressure testing and drainage of piping system Pipe leak test, system vacuuming, system fluorine filling, test machine debugging, operation, system final finishing, acceptance
2. Installation points and technical requirements:
1. Partition wall perforation and treatment:
   Due to the system pipeline and drainage requirements, it is necessary to pass through the warehouse and On the wall, the location and size of the hole to be opened should be approved. After correct, the size of the hole to be opened should be marked on the wall panel to be punched. The wall perforation must be consulted by the on-site civil engineering technical personnel. After the impact, the perforation operation can be carried out. The pipeline passes through the hole in the wall and is perforated with an electric hammer. If the wall that is not suitable for electric hammer perforation can be perforated in other ways after obtaining the consent of the owner. The size of the hole is based on the size of the pipe that can pass through the pipeline (including the thermal insulation layer). Steel casing should be installed where the pipeline passes through the wall. The welding seam of the pipeline should not be placed in the casing. The galvanized iron casing should be flat with the wall or floor. It should be at least 20mm higher than the ground. The gap between the pipeline and the casing should be filled with heat insulation or other non-combustible materials, and the casing should not be used as a support for the pipeline.
2. Installation of the unit in the warehouse:
   Steps: determine the position of the unit in the warehouse → draw the line mark → reamer and ream the hole → fix the support rod on the top of the warehouse → connect the screw on the ceiling of the unit → fix the unit in the warehouse
3. Refrigerant piping:
(1) Steps: piping according to the drawing requirements → piping laying → welding → blowing → leak testing → drying → heat preservation
(2) Principles The refrigerant piping should strictly abide by the three piping principles: dryness, cleanliness, and air tightness.
Drying is first to prevent moisture from entering the copper pipe before installation, and secondly to blow clean and vacuum dry after piping. Cleaning is to pay attention to cleaning the inside of the pipe during construction, and then nitrogen displacement welding during welding, and finally blowing. The air tightness test is to ensure the welding quality and the quality of the bell mouth connection, and the second is the final air tightness test.
(3) Method of replacing nitrogen:
   nitrogen protection must be used when the refrigerant pipe is brazed. When welding, the micro-pressure (3~5kg/cm²) nitrogen is filled into the pipe being welded, which will effectively prevent the generation of oxide scale in the pipe.
(4) Covering the refrigerant pipe:
   The cover of the refrigerant pipe is very important. To prevent moisture, dirt, dust, etc. from entering the pipe, the refrigerant pipe must be tightly wrapped with the pipe head through the wall. The nozzle is bandaged.
(5) Blowing out
   the refrigerant pipe: Blowing out the refrigerant pipe is the best way to remove the waste in the pipe. Blind plugs are good to keep. An indoor unit interface is used as a sewage outlet, and the pipe mouth is pressed against the insulating material, and the pressure regulating valve 5kg/cm² is inflated into the pipe, and the insulating material is quickly released when the hand cannot hold it, and the dirt and water are discharged together with the nitrogen gas. This cycle is repeated several times until no dirt and moisture are discharged (every indoor unit should do it).
In addition, the liquid pipe and the trachea should be carried out separately.
(6) Brazing of refrigerant pipes:
   a. Preparation before brazing of refrigerant pipes: the quality standards of brazing rods, the preparation of welding equipment, the surface of the copper pipe incision should be flat, and there should be no defects such as burrs and back convexity, and the incision plane is allowed to be inclined , the deviation is 1% of the diameter of the pipe.
  b. The refrigerant pipe should be brazed with phosphor copper or silver electrodes. The welding temperature is 700-845℃. The brazing work is easy to be carried out in the downward or horizontal direction, and overhead welding should be avoided as much as possible. , the branch port of the joint must be kept horizontal.
  c. The standard for the spacing of horizontal pipe (copper pipe) supports is as follows:
   nominally below Φ20 Φ25-40 Φ50
   Interval (m) 1.0 1.5 2.0
   Note: copper pipes cannot be clamped with metal brackets, and should be kept in a natural state through thermal insulation The layer supports the copper tube to prevent cold bridges.
  d. Welding personnel should have the necessary qualification certificates before they can take up their posts.
  e. When welding the gas pipe to operate the valve, it must be cooled (wrapping the valve body with a damp cloth), otherwise it will lead to leakage
(7) Copper pipes with a diameter smaller than Φ19.05mm should be simmered on site, hot-bent or cold-bending special bending For manufacturing tools, the ellipticity should not be greater than 8%, the bending radius of the pipes installed in parallel should be the same, and the spacing, slope aspect and inclination should be the same. Copper pipes larger than Φ19.05mm should use stamping elbows.
(8) Flare connection: The connection between
the refrigerant copper pipe and the indoor unit adopts the bell mouth connection, so pay attention to the expansion quality of the bell mouth. The flaring depth of the bell mouth should not be less than the diameter of the pipe, the direction of the flaring should be in the direction of the refrigerant flow, the cutting knife should be used to cut the pipe, and a little refrigeration oil should be applied to the inner surface of the flaring when flaring and locking the nut. The torque of the nut is as follows:
Nominal diameter Tube outer diameter Copper tube flare size Torque (kgf-cm)
   1/4 Φ6.35 9.1-9.5 140-180
   3/8 Φ9.52 12.2-12 ．8 340-420
   1/2 Φ12.7 15.6-16.2 340-420
   5/8 Φ15.88 18.8-19.4 680-820
   3/4 Φ19.05 23.1-23.7 1000-1200
4. All refrigerant pipe insulation pipes must be wrapped with wrapping tapes, and steel casings should be used when passing the floor.
5. Installation of drainage pipe: The drainage pipe adopts PVC or PPR engineering plastic pipe:
(1) Steps: connect the water pipe → lay the heating wire → check the water leakage → heat insulation
(2) The dirt and rust in the pipe must be removed before the installation of the pipe, and the opening of the pipe should be closed and protected during the installation pause.
(3) The shorter the effective distance of the drainage pipe in the silo, the better, and the slope of the horizontal pipe should be 1/100 to 1/50 to the drainage outlet.
(4) It is best to make a soft connection between the drain outlet of the tray in the library and the drain pipe, and the drain port of the condensate tray in the library should be higher than the interface of the drain pipe, and the PVC pipeline should be connected with special PVC glue. The leakage test of the drainage water system may adopt the water filling test, and no leakage is qualified.
(5) After the pipeline is installed, the system should be flushed, and the system should be cleaned before connecting.
6. Control line operation:
   The control lines are all bundled and laid along the refrigerant pipe with shielded wires, and the indoor controller is partially hidden through the pipe. It is forbidden to bundle the power line and the control line together to prevent interference.
7. Insulation work:
   The insulation work should be selected according to the design requirements. During construction, the insulation sleeve should be worn together, and the welding joint should be reserved. Finally, the welding joint should be processed. It is absolutely forbidden to break the insulation layer during construction, and the overlap of the insulation casing must be bundled with tape.
8. Installation of units outside the warehouse:
(1) Unpacking inspection of the equipment outside the warehouse, and filling in the inspection record in the equipment unpacking inspection record form;
(2) Handling and hoisting of the equipment outside the warehouse;
(3) The unit outside the warehouse is located in On the roof foundation (civil construction cooperation), the unit and the foundation are fixed with feet or brackets. The connection between the outdoor unit and the indoor unit, and between the outdoor unit and the building should be done according to the relevant technical regulations.
9. Air tightness test:
(1) Operation sequence: completion of refrigerant piping → nitrogen pressurization → time control → pressure inspection → qualified
(2) organization and division of labor of test personnel.
(3) Essentials: The refrigerant pipe must be pressurized with dry nitrogen, and the pressure is slowly tested:
   the first stage: pressurize at 3.0 kg/cm² for more than 3 minutes;
   The second stage: pressurize 15 kg/cm² for more than 3 minutes;
   the third stage: pressurize 30 kg/cm² for 24 hours
   to observe whether the pressure drops, if there is no drop, it is qualified, but the temperature changes and the pressure will change. The pressure will vary by 0.1 kg/cm², so it should be corrected. To check for leaks, feel, hear, and soapy water for leak detection. After the nitrogen pressure test is completed, put nitrogen to 3 kg/cm², add R22, and use an electronic leak detector to detect leaks when the pressure reaches 5 kg/cm².
(4) The air tightness test record must be filled in the test process (the record filled in with clear words and true data)
10. Vacuum drying:
(1) After the nitrogen pressure test is qualified, the system should be vacuum dried, and the vacuum drying should meet the quality requirements.
(2) Rotary vacuum pump (exhaust volume 4l/min) should be selected for vacuum drying. Before use, check the vacuum pumping capacity of the vacuum pump to -755mmHg before proceeding.
(3) In the following order:
  ⑴Connect the vacuum gauge and run the vacuum pump for more than 2 hours (the vacuum degree should be above -755mmHg), if it cannot reach -755mmHg, continue to pump for 1 hour.
  (2) After reaching -755mmHg, it can be placed for 1 hour, and it is qualified if the vacuum gauge does not rise. If the rise indicates that there is moisture or air leakage in the system, it should continue to be processed.
  (3) After the vacuum test is qualified, add the calculated amount of refrigerant and open the valve (note that the vacuum should be carried out from both sides of the gas pipe and the liquid pipe).
  ⑷ Under special circumstances, a special vacuum drying method with nitrogen separation can be carried out.
(4) Record the above test situation in the relevant form.
11. Filling of Freon refrigerant: The filling of
   refrigerant shall be carried out according to the requirements of the technical data.