China thermal insulation steel pipe factory
Thermal insulation pipeline is widely used in liquid and gas transmission pipe network, chemical pipeline thermal insulation engineering, petroleum, chemical industry, central heating network, central air conditioning ventilation pipeline, municipal engineering, etc. Steel jacketed steel composite insulation steel pipe.
The thermal insulation structure of steel jacketed steel composite thermal insulation steel pipe can be divided into two categories according to different sliding modes:
1. Internal sliding type: the thermal insulation structure is composed of working steel pipe, aluminum silicate, drag reduction layer, microporous calcium silicate, thermal insulation layer, stainless steel fastening steel strip, aluminum foil reflection layer, polyurethane thermal insulation layer, outer steel pipe and external anti-corrosion layer. The inner sliding type heat preservation steel pipe is composed of a pipe conveying medium, a composite silicate or a microporous calcium silicate, a rigid polyurethane foam plastic, an outer steel pipe and a FRP shell anticorrosive protective layer. The thermal insulation treatment technology of various pipe fittings is mature and the quality is reliable.
2. External sliding type: the thermal insulation structure is composed of working steel pipe, glass wool thermal insulation layer, aluminum foil reflection layer, stainless steel fastening steel belt, sliding guide support, air insulation layer, external protective steel pipe and external anti-corrosion layer.
1. Inner steel pipe
2. Zinc rich primer
3. Sliding guide bracket
4. High temperature resistant glass wool
5. Aluminum foil reflector
6. Air insulation layer
7. Jacket steel pipe
8. Outer steel pipe anti-corrosion coating
Steel jacketed steel composite insulation steel pipe is one of the underground direct buried pipelines. It can also be buried underground without concrete structure, that is, the thermal expansion of the working steel pipe is carried out in the outer pipe, which reduces the material cost, shortens the construction date, ensures the safety of the heating pipeline, and can be more safely and widely used in different temperature environments, It is especially suitable for high temperature steam pipeline projects. The service temperature can reach 150 ℃ - 450 ℃. The pipe ends are generally sealed with polyethylene film or three-layer PE cold winding tape to prevent moisture or water from entering before installation or during construction. The multi-layer staggered binding of thermal insulation materials effectively reduces the heat loss. At the same time, control measures are taken on the outer sleeve surface to prevent the generation of cold bridge, so as to ensure the temperature control of the outer sleeve anti-corrosion coating. The multilayer aluminum foil reflective layer is wrapped with thermal insulation material, which effectively reduces the heat loss and makes the steam pipeline more economical and reasonable. The drainage system is fully enclosed, with flexible layout, reasonable structure, safety and reliability. The moisture discharge pipe on the steel casing can not only discharge the humid gas in time, but also serve as an alarm signal pipe for daily operation. The thermal compensation of the pipeline adopts high-quality bellows compensator, which is installed in the casing and made into a directly buried form. There is no need to set an observation well. The construction operation is convenient and the construction period is short. It is suitable for conveying steam or other media below 2.5MPa and 350 ℃. The product uses steel pipe as the outer protective layer, which has the advantages of high strength, not easy to damage, simple construction and maintenance and long service life.
In order to reduce the heat dissipation of the pipeline to the soil, a thermal insulation composite layer is added to the outside of the pipeline on the medium and small-diameter heat transmission crude oil or heating pipeline. The commonly used thermal insulation material is rigid polyurethane foam, and the temperature is between 18 and 120 degrees. This material is soft in texture. In order to improve its strength, a layer of high-density polyethylene layer is applied outside the thermal insulation layer to form a composite material structure to prevent groundwater from penetrating into the thermal insulation layer. A complete set of high-pressure polyurethane foaming equipment is used to shot blast rust removal on the outer surface of steel pipe and corona treatment on the inner surface of outer protective pipe, so as to improve the bonding performance of thermal insulation pipe. The insulating layer material is a rigid polyurethane foam with a density of 60kg/m3 to 80kg/m3. The gap between the steel pipe and the casing is fully filled and has certain bonding strength, so that a solid whole can be formed between the three parts of the steel pipe, the outer sleeve pipe and the insulation layer. Polyurethane foam has good mechanical properties and thermal insulation properties. Under normal circumstances, it can withstand temperatures of 120 degrees Celsius. It can withstand temperature of 180 degrees by modifying or combining with other insulation materials.
Prefabricated polyurethane insulated steel pipe is divided into three layers from the inside to the outside:
First floor: working steel pipe floor
According to the design and customer requirements, seamless steel pipe, spiral steel pipe and straight seam steel pipe are generally selected. After the steel pipe surface is treated by advanced shot blasting, the rust removal grade of steel pipe can reach SA2 in GB / t8923-1988 standard, and the surface roughness can reach r = 12.5 microns in gb6060.5-88 standard.
Second layer: polyurethane insulation layer
The rigid polyurethane foam plastic is injected into the cavity formed between the steel pipe and the outer sheath by the high-pressure foaming machine, which is commonly known as "tube in tube foaming".
Third layer: high density polyethylene protective layer
Prefabricated into black or yellow polyethylene plastic pipes with a certain wall thickness. Polyethylene is odorless, non-toxic and feels like wax. It has excellent low temperature resistance. The minimum service temperature can reach - 70 ~ - 100 ℃. It has good chemical stability, can resist the erosion of most acids and bases (not resistant to acids with oxidizing properties), is insoluble in general solvents at room temperature, and has low water absorption. However, because it is a linear molecule, it can slowly dissolve in some organic solvents without swelling, Excellent electrical insulation. Its function is to protect the polyurethane insulation layer from mechanical hard objects, and the other is anti-corrosion and waterproof. High density polyethylene polyurethane foam insulation steel pipe shall comply with SY / t114-2000 and SY / t115-2001 standards.