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Suitable for insulation in heating systems, domestic hot water or steam pipelines and equipment, as well as anti-condensation insulation for water supply pipelines. I. Construction Preparation 1. Main materials: Performance of insulation materials. The specifications shall meet the design requirements and be accompanied by a certificate of conformity. Commonly used materials include: rock wool, slag wool, and stitched felts; rock wool and slag wool tubes and shells; ultra-fine glass wool products; glass wool felts; glass wool sheet panels; microporous calcium silicate products; rigid polyurethane plastics; foam glass; aluminum silicate products, cement perlite products, and water-repellent perlite products. Polystyrene foam pipes and shells, etc. 1. 2 Main tools 1.2.1 Tools: steel scissors, fabric scissors, hammer, chisel, hook, iron mallet, ash bucket, trowel, curved trowel, etc. 1.2.2 Others: steel tape measure, steel needle, straightedge, wooden feeler gauge, etc. 1. 3 Working conditions 1.3.1 The strength tests and airtightness tests of the equipment and pipelines must pass ； 1.3.2 Remove dirt and rust from the surfaces of insulated equipment and pipelines, and apply an anti-corrosion coating. 1.3.3 All supports, hangers, structural accessories, and instrument connection components for the equipment and pipelines have been installed; hardwood pads have been placed in appropriate locations to prevent moisture damage. 1.3.4 Preparation for fixing the support components in place ； 1.3.5 The electric heat tracing or hot medium piping has been installed and is ready, having passed the power-on test or pressure test successfully ； 1.3.6 Complete the handover procedures for tasks such as the installation, welding, and anti-corrosion treatment of equipment and pipelines. II. Operating Procedures 2.1 Process Flow: Installation of insulation layer, installation of protective layer, application of paint, inspection of the anti-corrosion layer, inspection of the insulation layer, inspection of the protective layer, and final acceptance of the insulation work. 2.2 Insulation layer installation 2.2.1 Installation of insulation fixation and support elements: Vertical pipes and equipment must be equipped with load-bearing rings (or clamps) for the insulation layer at regular intervals; the width of these rings should be 2/3 of the thickness of the insulation layer. Nails are used to secure the insulation layer, with a spacing of 250-350 mm ； When used to secure the metal outer protective layer, space at 500-1000 mm intervals ； Ensure that there are no less than 2 nails at each end of each metal plate; when using support rings to fix the external metal protective layer, the spacing between each support ring should be 1200–2000 mm. And ensure that each metal plate has two support rings. 2.2.2 Shell and tube assemblies are used for insulating pipes with a diameter of less than DN350; the inner diameter of such assemblies should match the outer diameter of the pipes. During installation, the cut ends of the shell and tube assemblies are fitted over the pipes. When insulating horizontal pipes. The cut is located at the lower side of the pipe. For shell and tube units with a composite insulation layer, the protective paper inside the joint area at the cut should be removed, and the joint should be pressed flat. The adjacent sections of the tube shell should be pressed tightly together, with pressure-sensitive tape used to seal any gaps ； For pipe shells without an external protective layer, they can be tied up using galvanized iron wire or plastic rope, with 2–3 ties per section of the pipe shell. 2.2.3 The insulation panels are used for insulating flat walls or equipment with large curved surfaces. During installation, the cotton panels should be pressed tightly against the outer surface of the equipment; for curved surfaces, the seams between the panels need to be cut at an angle so that they can be joined together. These panels are usually fixed in place using self-locking plates fitted with pins. For equipment where welding pins are not suitable, it can be tied up with steel strips, with no less than two strips per cotton board; the corners should be covered with galvanized iron sheet before being tied up. 2.2.4 When the thickness of the insulation layer exceeds 80 mm, insulation should be applied in layers; double or multiple insulation layers should be laid with staggered joints and tied together layer by layer. 2.2.5 For equipment and pipeline supports, hangers, as well as components such as flanges, valves, and manholes, a certain amount of clearance for installation and removal should be reserved during the overall insulation process. Local insulation treatment shall be carried out after the overall insulation and protective layer construction are completed. Also, ensure that the completed insulation structure does not prevent the sliding of the movable support. 2.2.6 The thermal insulation thickness and density of the insulation felt and pads should be uniform, their shape should be regular, and the bulk density after compaction and bundling must meet the installation density specified in the design. 2.2.7 Insulation shall be applied to the ends of pipes or areas equipped with blind flanges, and these areas shall be sealed. Except for pipes specified in the design to be insulated as part of the tube bundle, all other pipes shall be insulated separately. The insulation layer after installation must not cover the equipment nameplates. If the insulation surrounding the nameplate is cut into a flared opening, the opening should be sealed neatly. 2.2.8 When insulation materials are used to insulate the corners of square equipment or square pipes, the joints at those corners should be sealed with overlapping seams; vertical gaps must not form. 2.2.9 The longitudinal joints of horizontal pipes shall not be located within 450 mm of the vertical centerline of the pipe; however, when multiple molded insulation units with large diameters are used, the longitudinal joints of the insulation layer are not subject to this restriction. But it should deviate from the pipe’s center of gravity line. 2.2.10 The seam width of thermal insulation products should generally not exceed 5 mm, and care must be taken to arrange the seams in a staggered pattern during installation. When using more than two layers of insulation materials, not only should the seams within the same layer be offset from each other, but the seams between the inner and outer layers should also be aligned; the overlap length should not be less than 50 mm. When sealing the insulation layer of the outer shell with adhesive tape, it is possible to avoid gaps. 2.2.11 The installation of hooks or pins generally involves the use of specialized hooks and pins. It can also be made from galvanized iron wire or low-carbon round steel with a diameter of ф3∽6mm, and welded directly to carbon steel equipment or pipes. The spacing between them should not be greater than 350 mm. Number of hooks or pins per unit area: at least 6 per m2 on the sides, and at least 8 per m2 at the bottom. When welding hooks or pins, use a chalk line to mark the position of each hook or pin on the equipment or pipe walls in alternating or aligned rows first. 2.2.12 The installation of supports: the material of the supports should be determined based on the material of the equipment or pipes. It is advisable to use ordinary carbon steel plates or section steel for fabrication. The support members must not be installed at locations where attachments are present; the annular surface should be level, and the installation error between the various bracket ribs should not exceed 10 mm. When direct welding to the equipment is not allowed, clamp-type supports should be used. 2.2.13 The width of the support components shall be 10 mm less than the thickness of the insulation layer, but shall not be less than 20 mm. The installation spacing for vertical equipment and supports for vertical pipes with a nominal diameter greater than 100 mm should be determined based on the degree of looseness of the insulation material. 2.2.14 For square equipment with reinforcing plates on the walls and the insulation layers of air ducts, these reinforcing plates can be used in place of support members; bent grooves can also be welded along the edges of the reinforcing plates. 2.2.15 Fixings that are welded directly to stainless steel equipment or pipes must be made of stainless steel. When the fasteners are made of carbon steel, stainless steel gaskets should be welded on. When the medium temperature is above 200°C and the equipment or pipeline is made of non-ferritic carbon steel, gaskets such as asbestos sheets should be installed between the band-type fasteners and the equipment or pipeline. 2.2.16 Insulation work for vibrating parts of the equipment: When fixing screws are already installed on the housing, weld them in place after tightening the nuts ； For the installation of the equipment head fasteners, when welding is used, a support ring can be welded at the intersection point between the head and the cylinder, and a fixing ring should be welded intermittently on this support ring ； When welding is not permitted for the equipment, the support ring should be replaced with a clamping type. Multi-layer insulation layers should use stainless steel movable rings, fixed rings, and steel strips. 2.2.17 When using semi-rigid insulation materials for the insulation of vertical equipment or vertical pipes, construction should start from the supports, proceeding upwards, with the material being tied together in a circular pattern using galvanized iron wire or packaging steel strips ； When a horizontal unit is equipped with brackets, the insulation layer should be assembled starting from the brackets and tied up with galvanized wire mesh. When a plaster protective layer is used, galvanized wire mesh should be wrapped around it. For vertical pipes with a nominal diameter of 100 mm or less and without fixing elements, No. 8 galvanized wire should be twisted into twisted loops on the pipe wall, and these twisted wires are then used to secure the insulation layer in place. 2.2.18 When installing the insulation layer for reducers, the insulation material should be shaped into fan-shaped pieces, and it should be tied together in a circular or mesh pattern; the tying wires should be connected longitudinally to those used for tying the larger-diameter pipe sections. 2.2.19 When there are no pre-formed products for the insulation layer at the elbow section, a regular straight tube shell should be cut and shaped into a shrimp-like curve. For pipes with a diameter of Dn≦70mm, or those that are difficult to shape into a shrimp-shaped profile due to a small bending radius, insulation felt can be used for padding and binding. For the installation of the insulation layer on the head, the product panels should be cut into fan-shaped pieces according to the dimensions of the head, and laid with overlapping seams. One end of the binding material should be tied to the movable ring, while the other end should be tied to the fixed ring or bracket at the cutting point, forming a radially oriented tightening strip. If necessary, ring-shaped tension strips can be tied between the tying strips; these ring-shaped tension strips should be tied to the tying strips in a cross-shaped knot. When the insulation layer of the head is of a double-layer structure, it should be tied in layers. 2.2.20 The construction of the insulation layer for the heat tracing pipes shall comply with the following provisions. The straight pipe sections should be securely tied together every 1.0 to 1.5 meters using galvanized iron wire. When there is no requirement to prevent local overheating, the main pipe and the heat tracing pipe can be tied together directly ； Otherwise, an asbestos gasket must be placed between the Supervisor and the heat tracing pipe. When using cotton felt or insulation padding, it should first be wrapped with galvanized wire mesh and tied tightly. Do not block the heating element before attempting to insulate it. 3. Construction of the protective layer 3.1 Metal protective layer (1) Metal protective layers are commonly made of galvanized steel sheets or aluminum alloy sheets. When ordinary steel plates are used, their inner and outer surfaces must be coated with anti-rust paint. (2) Before installation, two semi-circular flanges should be pressed out on both sides of the metal plate first. For equipment insulation, to enhance the strength of the metal plates, two intersecting reinforcement bars can be pressed along the diagonal of each metal plate. (3) Vertical insulation construction: Overlap the semi-circular flanges of two adjacent metal sheets, pressing the upper sheet down on the lower one from bottom to top, with an overlap of 50 mm. When fixing with pins, use a wooden hammer to drive through the thin plate at the location of the pin, remove any small pieces of debris from around the hole, insert a 3mm thick rubber gasket, and then use a self-locking plate to compress it in place (or tighten it with an M6 nut). When using support rings or plates for fixation, align the overlapping parts of the plate surfaces as closely as possible with the support rings or plates; first drill holes using a 3.6mm drill bit, and then secure them with M4*15 self-tapping screws. (4) For the insulation of horizontal pipes, metal sheets can be directly wrapped around the insulation layer, with installation carried out from bottom to top in accordance with the slope direction of the pipe ； The circumferential semi-circular flanges of the two plates overlap, with the longitudinal overlaps facing downward; the overlap at the joint is 50 mm. (5) At the joints, drill holes first using a¢4mm (or¢3.6mm) drill bit, and then secure them with pull-out rivets or self-tapping screws; the spacing between the rivets or screws should be 150-200mm. (6) Considering the thermal expansion displacement of equipment and pipelines during operation, the metal protective layer should have appropriate movable joints in the direction of expansion and contraction. (7) The metal protective coatings of insulation equipment and pipes in open or humid environments, as well as their accessories, must be filled with sealant as specified or sealed with sealing tape at the joints. (8) It is strictly prohibited to step on or stack items on the installed metal enclosure. When it is inevitable, temporary protective measures should be taken. 3.2 Composite protective layer: (1) Bitumen felt: Used as an external insulating protective layer for pipes and small cylindrical equipment in humid environments. It can be laid directly over the insulating layer, installed vertically from lower to higher positions, with the overlaps sealed together using asphalt. For horizontal pipes, the longitudinal seams should also overlap by 50 mm each, after which they are secured with galvanized wire or steel strips at intervals of 200–400 mm. (2) CPU roofing material: Used as an external insulating protective layer for pipes and small cylindrical equipment in humid environments. It can be directly rolled and laid outside the insulation layer, applied from lower to higher areas ； The overlap width of both the pipe rings and the longitudinal seams is 50 mm; they can be secured directly with a stapler, and the seams should be sealed with CPU sealant. (3) Glass cloth: Wrapped tightly in a spiral pattern around the insulation layer (or asphalt shingle, CPU sheet), with overlaps of 50 mm at both the front and back. Construct from the lower to the higher areas; tie the ends of the straps as well as every 3 meters using galvanized iron wire or steel strips. (4) Composite aluminum boxes (kraft paper-reinforced aluminum foil, glass cloth aluminum foil, etc.): can be directly applied over flat insulation layers other than cotton and felted materials. Seams are sealed with pressure-sensitive tape. (5) Glass cloth emulsified asphalt coating: Emulsified asphalt is applied to the outer surface of the wrapped glass cloth, at a rate of 2–3 kg/m2 per application. Generally, two coats are applied, with the second coat being applied after the first one has dried. (6) Glass fiber reinforced plastic: Unsaturated polyester resin is applied to the outer surface of the wrapped glass cloth, at a rate of 1–2 kg/m2 per application. (7) Fiberglass reinforced plastic, aluminum box fiberglass reinforced plastic sheets: The construction method is the same as that for metal protective layers, but the semi-circular flanges and folded lines are not pressed. Circular and longitudinal lap: 30-50mm. The joints can be fastened using core pull rivets or self-tapping screws, while the seams should be sealed with adhesive. 2. 3 Plaster protective layer (1) The mortar used for the plaster protective layer shall meet the following requirements: l The bulk density shall not exceed 1000 kg/m3; l The compressive strength shall not be less than 0.8 Mpa (80 kg/cm2); l The loss on ignition (including organic and combustible substances) shall not be more than 12% ； No cracks or peeling shall occur after dry firing (in a cold state) ； It must not cause corrosion to metals. (2) For open-air insulation structures, a plaster protective layer shall not be used. When it must be used, a protective layer of felt, foil, or fabric should be wrapped around the plastering layer, and a waterproof, weather-resistant coating should be applied to the surface of this wrapping layer. (3) The finishing protective layer should be protected from rain and water splash until it has hardened. When the average outdoor temperature during day and night is below 50°C and the lowest temperature reaches -30°C, winter construction procedures should be followed, and cold protection measures must be taken. (4) When applying the finishing coat to large-scale equipment, crosshatched grid or circular expansion joints should be left on the finishing coat protective layer. The expansion joint should be in the form of a groove, with a depth of 5–8 mm and a width of 8–12 mm. (5) The finishing protective layer of high-temperature pipelines and the gaps in the wire mesh should be located at the same position as the expansion joints of the insulation layer; these gaps should be filled with felt or cotton materials. For outdoor high-temperature pipes, metal shields should be installed at the expansion joints. 3. 4 When using chemical materials or coatings, obtain the performance and usage instructions from the relevant manufacturer. When fire protection is required, self-extinguishing coatings and sealing materials should be selected. 4.5 In areas with fire protection requirements, two coats of fire-retardant paint should be applied to pipes and equipment. 4. Paint: For external protective layers such as glass cloth and galvanized steel sheets, various colors of paint can be applied as per design or environmental requirements, either for protection or as identification marks. 5. Inspection of the anti-corrosion coating: Before insulation work is carried out, it is necessary to check whether the anti-corrosion coating applied to the outer surfaces of pipes and equipment is even; after the insulation work is completed, it is necessary to check whether the anti-corrosion coating and color markers applied to the protective layer surrounding the insulation structure are even and whether the paint film is firmly attached ； Are there any defects such as peeling or bubbles? ； Check whether dielectric color rings and flow direction arrows have been applied as required; any deficiencies should be corrected. 6. Inspection of the insulation layer: (1) Check whether the insulation fixing elements and supporting components are installed correctly and firmly; the supporting components must not be exposed, and their installation spacing should meet the design requirements. Anti-fall supporting elements must be provided for the metal protective layers on vertical pipes and flat surfaces. The self-locking plate must not slide outward. (2) Check whether the insulation method and thickness of the insulation layer meet the design requirements. The thickness of the insulation layer can be checked using a pin-type thickness gauge or a steel probe. During inspection, a steel needle should be inserted vertically at four corresponding points around the pipe, all the way to the pipe wall, after which a steel ruler should be used to measure the thickness, with a reading accuracy of ±1 mm. For horizontally installed pipes, two points located horizontally relative to the pipe’s axis should be selected to puncture the insulation layer, after which the thickness should be measured; the allowable deviation for this thickness is 10–15%. (3) The sampling points for quality inspection are as follows: for equipment, three samples should be taken every 50 m2, and for pipelines, three samples should be taken every 50 m. If one of these samples fails to meet the standards, additional sampling should be carried out at the nearest location for reinspection; if still half of the samples fail to meet the standards, that area shall be deemed non-compliant. When inspecting insulation work for the same pipeline over 500 m2, the spacing between sampling points can be increased. (4) The inspection of the bulk density of the insulation layer should be carried out by taking samples on-site; for seam-felt type insulation layers, the allowable deviation in their installed bulk density is 10℅ ； For plate and shell insulation layers, it is 5%. (5) It should be checked whether the ends of the pipeline insulation structure prevent the installation and removal of bolts on pipeline fittings (such as flanges, valves, etc.) and the opening of door covers. 7. Inspection of the protective layer: (1) Except for pipes located in buried areas or inaccessible trenches, the flatness of the protective layer should be checked using a 1M long straightedge; the allowable deviation for the plastering layer and the covering layer shall not exceed 5mm ； The allowable deviation of the metal protective layer shall not be greater than 4 mm. (2) The visual inspection of the protective layer shall comply with the following requirements: 1) The plastering layer shall be free from looseness and dry-shrinkage cracks at low temperatures (except for hairline cracks); its surface shall be smooth and even, with well-defined contours, and no exposed wire ends shall be present. 2) Wrapping layer, metal protective layer: a. There shall be no loosening, flanging, cracks, or obvious dents. b. The circumferential joints of the pipe’s metal casing shall be perpendicular to the pipe axis. The longitudinal seam should remain parallel to the pipeline axis. The circumferential and longitudinal joints of the metal enclosures for equipment and large storage tanks should be perpendicular to each other and form straight lines. c. The seam direction of the metal enclosure should be consistent with the slope direction of the equipment and pipelines. d. The ellipticity of the metal protective layer (the difference between the major and minor axes) shall not exceed 10 mm. e. The overlap size of the metal protective layer shall meet the design requirements. 8. Completion acceptance of the insulation work: After the insulation work is completed, it must be inspected and accepted in accordance with relevant regulations. The following documents should be available at the time of acceptance: factory certificates of conformity or physical and chemical property test reports for the insulating materials, as well as other key auxiliary materials such as adhesives and sealants ； Mixing ratio of the plaster material for the finishing protective layer and test report on its technical properties ； Notice of Design Changes and Material Substitution ； Records of concealed works ； Quality inspection record ； Process handover record ； Summary tables for the completion of insulation work, etc. III. Quality Standards 1. Key parameters: The strength, bulk density, thermal conductivity, specifications of the insulation material, as well as the methods used for insulation, must meet the requirements specified in the design documents and construction standards. 2. General items: The surface of the insulation layer is smooth, the construction method is correct, the overlaps are proper, the seals are tight, and there is no bulging or loosening.