Production prefabrication directly buried hot water Thermal insulation pipe ：
The size of the prefabricated directly buried hot water insulation pipe trench shall meet the requirements shown in the figure: 1. When the bearing capacity of the soil layer at the bottom of the trench is ≤ 80KPa, the trench bottom shall be padded with plain concrete layer. 2. The upper layer at the bottom of the C15 plain concrete layer shall be compacted before pouring concrete. The surface of the concrete layer shall be smooth and flat. When the upper layer at the bottom is collapsible soil, it shall be replaced (about 1.0m deep) and compacted. 3. In trench Connector The trench width and * * * at the location shall be 250~300mm more than that at the non joint location. 4. With ripple Compensator Location of. The elevation of the soil layer at the bottom of the corrugated compensator shall be determined according to the actual arrival size of the compensator. 5. The slope of the upper layer of the trench bottom along the pipeline shall be the same as The Conduit The slope of is consistent. 6. For 100mm around directly buried pipeline fine sand Fill in. The diameter of sand shall not be more than 8mm, and the sand layer shall not contain clay, brick, stone, iron parts and other sundries. 7. When the pipeline is buried in highly corrosive soil sections such as slag and sundries, the backfill shall be replaced with less corrosive soil and compacted layer by layer.
Production of prefabricated directly buried hot water insulation pipe:
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Directly buried insulation pipe is divided into three layers from inside to outside
Front layer: the working steel pipe layer generally selects seamless pipe (GB8163-87), spiral welded pipe (GB9711-88; SY/T5038-92) and straight welded pipe (GB3092-93) according to the design and customer requirements. After the steel pipe surface is treated by advanced shot blasting, the steel pipe rust removal grade can reach Sa2 in GB8923-1988 standard, and the surface roughness can reach R=12.5 μ m in GB6060.5-88 standard.
The second layer: the polyurethane insulation layer is made by injecting the original liquid of rigid polyurethane foam into the cavity formed between the steel pipe and the outer protective layer with a high-pressure foaming machine at one time. It is commonly known as "pipe in pipe foaming process". Its functions are waterproof, thermal insulation and supporting the weight of the heating network. When the temperature of the conveying medium is - 50 ℃ - 120 ℃, rigid polyurethane foam is selected as the insulation layer.
The third layer: the high-density polyethylene protective layer is prefabricated into a certain thickness of black (* * *) plastic pipe. Its role is to protect the polyurethane insulation layer from mechanical hard objects, and to prevent corrosion and water.
The polyethylene outer sleeve is made of high-density polyethylene material, which has * * * high mechanical strength and excellent corrosion resistance, and can protect the pipe from damage caused by external factors during transportation, installation and use.
Antioxidant, ultraviolet stabilizer, carbon black, etc. shall be added to the outer sleeve manufacturing.
Production process
1. Feeding 2. Extrusion 3. Mould 4. Cooling 5. Traction 6. Corona treatment of inner surface 7. Cutting 8. Inspection 9. Finished product
explain
A. Polyethylene pipe is prone to aging. If it is stored in the open air, it should be covered with tarpaulin and other materials. The stacking place should be far away from high heat source and fire source. After the insulation pipe is made, it is forbidden to expose to the sun and cool suddenly, otherwise the polyethylene pipe is prone to cracking, affecting the product performance and service life.
B. During transportation and pipe threading, rough loading and unloading shall be avoided, and the hook shall be too thin, too hard and too hard, otherwise the polyethylene pipe may be damaged, scratched or torn.
C. The wall thickness of the pipe can be adjusted, and the wall thickness and color can be produced according to the user's requirements. Due to the different wall thickness of the pipe, the thickness of the insulation layer is approximately, which should be calculated according to the actual thickness.
D. The support, plastic plug, two end flange, welding rod, welding gun, heat shrinkable tape, etc. matched with the pipe are complete.
E. The allowable deviation in the table is formulated according to CJ/114-2000 industry standard.
The calculation formula is: when the outer diameter is ≤ 400mm, the sum of upper and lower deviations=0.1 × nominal wall thickness 0.2
When the outer diameter is ≥ 400mm, the sum of upper and lower deviations=0.15 × nominal wall thickness 0.2
Application of directly buried insulation pipe:
The polyurethane directly buried thermal insulation pipe is suitable for the thermal insulation and cold insulation engineering of conveying various media in the range of - 50 ℃ - 150 ℃. It is widely used in urban central heating, heating rooms, cold storages, coal mines, oil pipeline ports, chemicals, natural gas pipelines, power direct burial, * * * air conditioning pipeline insulation, cable conduits, steam insulation pipes and other industries for thermal insulation and cold insulation projects.
Advantages and characteristics of polyurethane directly buried insulation pipe
1. Reduce project cost. According to the estimation of relevant departments, the double pipe heating pipeline can generally reduce the project cost by about 25% (using glass fiber reinforced plastic as the protective layer) and 10% (using high-density polyethylene as the protective layer).
2. Low heat loss and energy saving. Its thermal conductivity is λ ＝ 0.013 - 0.03kcal ／ m? h?oC， It is much lower than other commonly used pipeline insulation materials in the past, and the insulation effect is improved by 4~9 times. Moreover, its water absorption is very low, about 0.2kg/m2. The reason of low water absorption is that the closed cell rate of polyurethane foam is up to 92%. The low thermal conductivity and low water absorption, together with the insulation layer and the high density polyethylene or glass fiber reinforced plastic protective shell with good waterproof performance outside, have changed the situation of traditional trench laying of heat supply pipes "wearing wet cotton padded jacket", greatly reducing the overall heat loss of heat supply pipes. The heat loss of the heat network is 2%, less than the standard requirement of * * * 10%.
3. Anti corrosion, good insulation and long service life. As the polyurethane rigid foam insulation layer is closely bonded to the outer skin of the steel pipe, it can isolate the infiltration of air and water and play a good anti-corrosion role. At the same time, its foam pores are closed, and its water absorption is very small. High density polyethylene shell and glass fiber reinforced plastic shell have good anti-corrosion, insulation and mechanical properties. Therefore, the outer skin of working steel pipe is difficult to be eroded by external air and water. As long as the water quality inside the pipeline is well treated, according to foreign data, the service life can reach more than 50 years, which is 3~4 times longer than that of traditional trench laying and overhead laying.
4. Small land occupation, fast construction and favorable environmental protection. Directly buried heating pipes do not need to build huge trenches, but only need to bury the insulation pipes underground, so the project land occupation is greatly reduced, the amount of earthwork excavation is reduced by more than 50%, and the amount of civil masonry and concrete is reduced by 90%. At the same time, insulation pipe processing and on-site trenching are conducted in parallel, and only on-site joints are needed, which can shorten the construction period by more than 50%.
5 Safety. The polyurethane directly buried insulation pipe is equipped with a leakage * * * line. Once a leakage occurs somewhere in the pipe, the transmission of the * * * line can show the exact location and degree of water leakage of the insulation pipe on the * * * detection instrument, so as to notify the leakage detection personnel to quickly deal with the leaking pipe section and ensure the safe operation of the heating pipe network. At present, no leakage * * * line has been set for insulation pipes produced in China, which needs to be filled in.
