brief introduction of heat preservation construction technology for pipelines and equipment

2118-3-26 8:39

1 Scope: This technology standard is applicable to heat preservation of hot water or steam pipelines and equipment for heating and domestic use, and dew prevention and heat preservation of water supply and drainage pipelines.

2 Construction preparation

2.1 Material requirements:

2.1.1 The performance and specifications of thermal insulation materials should meet the design requirements, and have the certificate of approval.

commonly used materials are:

2.1.1.1 precast tile: foam concrete, perlite, vermiculite, asbestos tile, etc.

2.1.1.2 Shell products: rock wool, slag wool, glass wool, rigid polyurethane foam plastic, polystyrene foam plastic shell and so on.

2.1.1.3 coiled material: polystyrene foam, rock wool, etc.

2.1.1.4 other materials: lead wire mesh, asbestos ash, or masonry or bonding with the above prefabricated plates.

2.1.2 protective shell materials include hemp knives, white ash or asbestos, cement and hemp knives; Glass fiber cloth, plastic cloth, sack cloth impregnated with asphalt oil, linoleum, industrial cotton cloth, aluminum foil paper, iron sheet, etc.

2.2 main machines and tools:

2.2.1 machines and tools: grinding wheel saw, electric welding machine.

2.2.2 Tools: steel bar, cloth scissors, hammer, chop, hook, shovel, ash bucket, flat trowel and circular trowel.

2.2.3 others: steel tape measure, steel needle, guide rule, wedge feeler, etc.

2.3 operating conditions:

2.3.1 heat preservation of pipelines and equipment can only be carried out after passing the anti-corrosion and water pressure test. If it is necessary to do heat preservation first, the joints and welds of pipelines should be set aside, and the joints should be insulated after passing the water pressure test.

2.3.2 The pipes that need to be insulated in the ceiling and tube well of the building must pass the anticorrosion pressure test, and the civil works can only be finally closed after the insulation is completed. It is forbidden to reverse the construction process.

2.3.3 before heat preservation, the sundries in the trench tube well must be cleaned up, and the sundries left over from the construction process should be cleaned up at any time to ensure the smooth flow of the trench.

2.3.4 the mortar protective shell for wet operation shall be protected against freezing in winter.

3 operation process

3.1 process flow:

3.1.1 precast tile:

loose tile → broken galvanized steel wire → mixed with ash → plastered with filler → combined tile → steel wire binding → caulking → plastered with protective shell

3.1.2 shell products:

loose shell → combined shell. → wrap protective layer

3.1.4 Equipment and steel wire mesh asbestos ash insulation welding hook nail → brush oil → bind steel wire mesh → wipe asbestos ash → wipe protective layer

3.2 All kinds of prefabricated tiles are transported to the construction site, and the specifications and sizes of tiles must be ensured to match the pipe diameter when they are scattered along the pipeline.

3.3 when installing the thermal insulation tile, the inside of the tile should be plastered with 5 ~ 11 mm asbestos mortar as filler. The longitudinal joints of tiles are staggered, and the horizontal joints should face up and down.

3.4 the prefabricated tile shall be bound and fixed with galvanized steel wire No.18 ~ No.21 according to its diameter, and the binding joint shall not be too long, and the joint shall be inserted into the tile.

3.5 after the precast tile is bound, it shall be filled in the gap with asbestos ash mud, and the joint shall be pointed and leveled.

3.6 The protective shell coated with asbestos cement (the ratio of asbestos ash to cement = 3: 7) shall be smoothed and calendered according to the thickness specified in the design, and the thickness shall be 11 ~ 15mm when there are no provisions in the design.

3.7 When the riser is insulated, its height is less than or equal to 5 m, and each layer shall be provided with a support tray, the height is more than 5 m, and each layer shall be at least 2, and the support trays shall be welded.

3.8 heat preservation of pipeline accessories Except for outdoor overhead pipelines and indoor anti-condensation heat preservation flanges, valves and other accessories in cold areas, flanges, valves, casing expansion joints and so on should not be heat preserved, and a gap of 71 ~ 81 mm should be left on both sides, and a slope of 61 ~ 71 should be smeared at the heat preservation end. The end of the insulation layer of manholes, handholes and detachable parts on the equipment container should be made into a 45 slope.

3.9 expansion joints should be left at the supports of thermal insulation pipes and filled with asbestos rope or glass wool.

3.11 precast tiles are used as pipeline insulation layer, and an expansion joint with a gap of 5～7m should be left every 5 ~ 7 m on the straight pipe section, and an expansion joint with a gap of 21 ~ 31 mm should be left at the bend with a pipe diameter less than or equal to 311mm, and the expansion joint should be filled with asbestos rope or glass wool, as shown in Figure 1-51. Fig. 1 -51

3.11 Using shell and tube products as insulation layer, the operation method is generally coordinated by two people. One person cuts the seam of shell and tube and wraps it on the tube, and then squeezes it with both hands. The other person wraps the protective shell, with even force, smooth stubble and consistent thickness. If the glass fiber cloth without edge sealing is used as the protective shell, the raw edges should be folded and not exposed.

3.12 The block insulation material adopts wrapped insulation (such as polyethylene foam), and the material is cut according to the pipe diameter. In order to ensure its smoothness and beauty, the summer-planting should generally be left on the inside of the pipe. Other requirements are the same as those in 3.11.

3.13, where the pipe insulation is made of iron sheet, the lap joint of the longitudinal seam should be downward, and the lap length of the iron sheet is 31 mm. The iron sheet protective layer at the bend is circular.

3.14 Generally, the insulation surfaces of equipment and tanks are relatively large. At present, foam concrete blocks or perlite blocks are widely used, and hemp knives, plaster and cement protective shells are applied outside. The lead wire mesh asbestos ash insulation method is to weld some hooks to fix the insulation layer outside the surface of the equipment. The spacing of the hooks is generally 211 ~ 251 mm, the diameter of the hooks is generally 6 ~ 11 mm, and the height of the hooks is the same as the thickness of the insulation layer. Fix the cut steel wire mesh with the hooks, and then apply asbestos plaster on it. It should not be too thick for the first time to prevent the adhesion from sagging and falling off. After the first time has a certain strength, continue to layer. Figure 1-52 1? .5mm iron sheet protective layer; 2 棻 n? Are you complaining about the meal? ×16 After the insulation layer is completed and has a certain strength, the protective shell shall be plastered, and it shall be polished and flattened.

4 Quality standard

4.1 Guarantee items:

The strength, bulk density, thermal conductivity, specifications and thermal insulation practices of thermal insulation materials should meet the design requirements and construction specifications.

inspection method: check the factory certificate and instructions of thermal insulation materials.

4.2 basic project:

the surface of insulation layer is smooth, the method is correct, the stubble is reasonable, the seal is tight, and there is no hollowing and looseness.

inspection method: observation and inspection.

4.3 allowable deviation items:

allowable deviation items are shown in table 1-42. allowable deviation of insulation layer

5 finished product protection

5.1 insulation of pipes and equipment can only be carried out on the premise that the trench and tube well have been cleaned and the insulation layer will not be damaged by the next process.

5.2 general pipeline insulation should be carried out only after the water pressure test is qualified and the anti-corrosion is finished, and the process cannot be reversed.

5.3 thermal insulation materials shall not enter the site in the rain or be stored in damp places.

5.4 the scraps left after heat preservation shall be cleaned by the construction team.

5.5 measures should be taken to prevent pollution of thermal insulation layer if shotcrete is used in civil engineering.

5.6 in case of special circumstances, if the insulation layer needs to be removed for pipeline treatment or other types of work damage the insulation layer during construction, it should be repaired in time according to the original requirements.

6 quality problems that should be paid attention to

6.1 improper use of heat preservation materials and unclear disclosure practices are unknown. Should be familiar with drawings, understand the design requirements, are not allowed to arbitrarily change the insulation practices, in strict accordance with the design requirements for construction.

6.2 the thickness of insulation layer is not constructed according to the design requirements. The construction is mainly based on experience, and the requirements for thermal insulation are not well understood.

6.3 the surface is rough and unsightly. Mainly because the operation is not serious and the requirements are not strict.

6.4 empty drum, loose not tight. The main reasons are that the size of thermal insulation material is not suitable, the force is uneven when wrapping, and the stubble position is unreasonable.

7 Quality records that should be possessed

7.1 Thermal insulation materials and auxiliary materials should have factory certificates.

7.2 there should be an acceptance record when entering the site, and its performance and specifications should meet the design requirements.

7.3 before heat preservation, pipes and equipment shall have concealed inspection and acceptance records.

7.4 after the completion of heat preservation, there should be an acceptance record.