Insulation standards for pressure pipelines
Thread Content
Recently, the company has been under maintenance, and my task was to oversee the restoration of insulation on pressure pipes. I had to keep a record of all the pipes and elbows that were inspected. It was quite boring doing this; I just chatted with the workers who were handling the insulation work, and then recorded everything in the ledger. The worker in charge of the insulation work said that there was some standard related to the insulation of pressure pipes and containers, but he wasn’t sure about the details. When I returned to my dormitory at night, I couldn’t find any information online, so I thought of coming here and asking everyone if there are any industry standards regarding insulation, or any experience or precautions related to it. Thank you all {:2_32:}
For reference: 1. GBT4272-2008 General Rules for Insulation Technology of Equipment and Pipelines; 2. SHS 01033-2004 Procedures for Maintenance and Inspection of Insulation and Cooling Systems for Equipment and Pipelines; 3. GB/T 8174-2008 Testing and Evaluation of the Insulation Effect of Equipment and Pipelines; 4. https://bbs.hcbbs.com/thread-954395-1-1.html
You can take a look at the SHS 01033-2004 regulations for the maintenance and repair of insulation and cooling systems for equipment and pipelines
Technical Specifications for Insulation, Corrosion Protection and Painting Design of Pressure Piping 1 Insulation Design 1.1 Insulation 1.1.1 General Provisions The insulation design must comply with GB50264—97 \"Design Code for Thermal Insulation of Industrial Equipment and Piping\", GB8175—87 \"Guidelines for Insulation Design of Equipment and Piping\", and GB15586—1995 \"Guidelines for Cooling Insulation Design of Equipment and Piping\". 1.2 Thermal insulation
1.2.1 Scope of application
(1) Thermal insulation is applicable when the temperature of equipment/pipelines is ≥50°C, and the heat loss meets the requirements specified in GB8175—87. (2) When required by the process, thermal insulation can be applied when the temperature of equipment/piping is ≤50°C. (3) For uninsulated equipment/pipes with a surface temperature of ≥60°C, insulation to prevent burns should be installed in the following areas at those parts that require regular maintenance and for which no other measures can be used to prevent burns. (a) The height above the local or working platform is less than 2.1 m. (b) Within 0.75m of the platform or walkway edge. (4) The following equipment and components do not require insulation. (a) Fans, compressors. (b) Expansion joints, hoses, rotating machines, slide valves, and other similar mechanical equipment. 1.2.2 Design (1) The design standards shall be in accordance with GB50264—97 and GB8175—87. (2) Calculate the insulation thickness based on the fluid temperature. (a) Usually the operating temperature of the fluid. (b) Use the design temperature when heat loss requirements apply. (c) When the actual temperature is unknown, the temperature of the corresponding saturated steam can be used. (3) The insulation thickness shall be specified by the project. (4) The heat protection thickness shall be specified by the project. 1.3 Cold insulation 1.3.1 Scope of application (1) Cold insulation is applicable to equipment/pipelines at ≤5°C, except in cases where heat absorption is required. (2) Cold insulation is suitable when the temperature of the equipment/pipes is ≥5°C but lower than the ambient temperature, mainly to prevent surface condensation. Condensation can lead to the following hazards: (a) Condensate can pose electrical hazards. (b) Condensation will damage the equipment. (3) Above-ground water pipelines and buried water pipelines at the freezing line must comply with the design requirements. (4) The insulation thickness table shall be specified by the project. (5) The anti-freezing thickness table shall be specified by the project. 1.4 Selection of Insulation Materials 1.4.1 Performance Requirements for Insulation Layer Materials (1) Insulation layer materials should be selected from those that provide equations or charts relating the thermal conductivity to temperature changes. For loose or compressed thermal insulation materials, products whose equations or charts for thermal conductivity at the intended service density are available should be selected. During the feasibility study and preliminary design phases, when performing thermal insulation calculations, the data specified in Appendix A of GB50264—97 “Code for Design of Thermal Insulation Engineering for Industrial Equipment and Pipelines” regarding the properties of commonly used thermal insulation materials may be utilized. (2) During operation, when the average temperature of the thermal insulation material is below 350°C, its thermal conductivity shall not exceed 0.12 W/(m·°C); when the average temperature of the heat-insulating material is below 27°C, its thermal conductivity shall not be greater than 0.064 W/(m·°C). (3) The density of the rigid insulation material shall not exceed 300 kg/m3 ； The density of soft materials and semi-rigid products shall not exceed 200 kg/m3 ； The density of the insulation material must not exceed 200 kg/m3. (4) The compressive strength of the rigid materials used for insulation shall not be less than 0.4 MPa ； The compressive strength of rigid materials used for cold preservation must not be less than 0.15 MPa. (5) The moisture content of the insulation material shall not exceed 7.5% (by weight; the same applies hereinafter) ； The moisture content of the insulation material must not exceed 1%. (6) The insulation layer material should be selected from products that can provide certification of having the permissible operating temperature, as well as non-flammability, flame retardancy, and combustibility properties ； For insulation materials, test certificates for water absorption, moisture absorption, and water repellency are also required. For rigid thermal insulation materials, data on the linear expansion or contraction rate of the material must also be provided. (7) The insulation materials used in contact with the surface of austenitic stainless steel shall comply with the regulations regarding chloride content specified in the \"Code for Construction and Acceptance of Insulation Works for Industrial Equipment and Pipelines\" (GB50185). Rigid insulating materials should not be used in vibrating pipes. (8) Depending on the different external surface temperatures of the process equipment and pipelines to be insulated, the combustion properties of the insulation material shall meet the combustion grade specified in the current **standard \"Method for Classifying the Combustion Properties of Building Materials\" (GB8624), and shall comply with the following requirements: (a) When the external surface temperature T0 of the equipment and pipelines to be insulated is greater than 100°C, the insulation material shall meet the performance requirements of Class A non-combustible materials. (b) When the outer surface temperature T0 of the insulated equipment and pipelines is less than or equal to 100°C, the insulation material must meet the performance requirements of flame-retardant Class B1 materials. (c) When the surface temperature T0 of the insulated equipment and pipes is less than or equal to 50°C, foam plastic insulation materials with a protective layer shall meet the performance requirements of materials classified as generally flammable, grade B2. 1.4.2 Performance requirements for waterproofing layer materials (1) The waterproofing layer materials should be those that possess resistance to steam penetration, water drainage capabilities, and moisture resistance, with a water absorption rate of no more than 1%. (2) The flammability of moisture barrier materials shall comply with the provisions of Clause 3.1.8 in GB50264—97 “Code for Design of Thermal Insulation Engineering for Industrial Equipment and Pipelines”. (3) The material for the moisture barrier should be one with stable chemical properties, that is non-toxic and corrosion-resistant, and it must not cause corrosion or dissolution of the materials used for the insulation layer and the protective layer. (4) The material for the moisture barrier should be one that does not soften, blister, or flow in summer, and does not become brittle, crack, or peel off when used at low temperatures. (5) For coating-type moisture-proofing materials, the softening temperature should not be lower than 65°C, and the adhesion strength should not be less than 0.15 MPa ； Volatile matter shall not exceed 30%. 1.4.3 Performance requirements for insulation layer materials: (1) The material used for the protective layer should have high strength; it must not soften or crack at the operating temperature, and it should also be resistant to aging. Its service life should be at least equal to the designed service life. **For critical projects, the designed service life of the insulation and protective layer materials should be more than 10 years. During cold storage, it should last for 12 to 18 years. (2) The protective layer material should possess properties such as water drainage, moisture resistance, resistance to atmospheric corrosion, and good chemical stability ； It shall not cause corrosion or dissolution of the moisture barrier or insulation layer. (3) The protective layer material should be made of non-flammable or flame-retardant materials. However, the protective coatings of equipment and pipelines used for storing or transporting flammable and explosive materials, as well as the pipelines adjacent to them, must be made of non-combustible materials. 1.4.4 Main performance requirements for adhesives, sealants, and wear-resistant materials: (1) Adhesives used for thermal insulation should maintain their adhesive properties within the low-temperature range of use; their adhesive strength at room temperature should be greater than 0.15 MPa, and their softening temperature should be above 65°C. The adhesive used for foam glass should have an adhesive strength greater than 0.05 MPa at -196°C. (2) The adhesives, sealants, and wear-resistant materials used shall not cause corrosion of the metal walls nor lead to the dissolution of the insulation material. Under conditions of expansion and vibration, the wear-resistant agent should prevent foam glass from being damaged due to friction with itself or with metals. (3) Adhesives and sealants should be selected such that they have a short curing time, good sealing properties, and do not crack over the design service life. 1.4.5 Insulation calculations can be carried out in accordance with Article 4 \"Insulation Calculations\" in GB50624—97 \"Design Code for Insulation of Industrial Equipment and Piping\", or by referring to other relevant standards. 1.5 Types of Insulated Structures 1.5.1 Based on different insulation materials and construction methods, they can be roughly divided into ten categories: (1) Clay structures. (2) Filling structure. (3) Bundling structure. (4) Winding structure. (5) Precast opening structure. (6) Prefabricated structure. (7) Irrigation structure. (8) Coating structure. (9) Metal reflective structure. (10) Detachable structure. 1.6 Types of protective layers 1.6.1 Based on the materials used and the construction methods, they can be divided into three categories: (1) Coated protective layers. (2) Metal protective layer. (3) Felt-based protective layer. (4) Others. 1.7 Insulated Structures 1.7.1 The selection of an insulated structure generally should be based on insulation or cooling materials, protective layer materials, as well as various conditions and requirements; however, the following points should also be taken into consideration. (1) A certain mechanical strength is required; the insulation structure should not detach under its own weight or due to external impacts. (2) The insulation structure is simple, easy to construct, and easy to maintain. (3) The outer surface of the insulated structure is neat and aesthetically pleasing. (4) The economic insulation structure refers to the fact that the insulating material is an \"economical\" one; an economical thickness and an economical outer protective layer together constitute an economic insulation structure. 1.7.2 For detailed construction drawings of adiabatic structures, reference may be made to CD42B1—84 “General Atlas for Thermal Insulation (50–600°C)”, CD42B2—84 “General Atlas for Cryogenic Insulation (+10 to -200°C)”, and Volume 4 of the “Construction Drawing Atlas for the Installation Design of Process Piping in Petrochemical Plants”, titled “Insulation for Pipes and Equipment”. 1.8 The construction and acceptance of insulation works shall be carried out in accordance with GB50185-93 \"Code for Construction and Acceptance of Industrial Equipment and Pipeline Projects\". 2 Coating for Corrosion Protection of Equipment and Pipelines 2.1 Overview To prevent corrosion of metals caused by industrial atmospheres, water, and soil, painting the exterior of equipment and pipelines is one of the important anti-corrosion measures in chemical enterprises. (The contents discussed in this section do not include other anti-corrosion methods such as cathodic protection.) Equipment, pipes, supports, platforms, railings, ladders, etc., made of carbon steel, low-alloy steel, or cast iron should generally be painted for corrosion protection. Non-ferrous metals such as aluminum, copper, and lead, austenitic stainless steel, galvanized surfaces, cathodically protected surfaces, metal surfaces coated with fire-resistant cement, as well as plastic and plastic-coated surfaces shall not be painted. Non-standard equipment, pipelines, and associated steel structures manufactured in the factory should be coated with two layers of anti-corrosion primer before leaving the factory (as specified by the manufacturer), with a topcoat being applied at the construction site. Equipment, pipes, and ancillary steel structures assembled at the construction site shall be painted on site. For equipment coated with paint by the manufacturer, if the paint is damaged during transportation, the damaged areas should be repainted on-site. The surfaces of the equipment’s nameplates and other signs or labels shall not be painted. 2.1.1 The selection of coatings shall follow the following principles: (1) It should be suitable for the operating conditions of the equipment and pipelines ； (2) Corresponding to the materials and surface treatment of equipment and pipelines ； (3) The primer, intermediate coat, and topcoat should be properly matched ； (4) Economically reasonable ； (5) Have the construction conditions. Anti-corrosion work must be carried out in accordance with **, the relevant current industry regulations, and the construction instructions provided by the manufacturers of the anti-corrosion materials. Pressure vessels and pipelines must be painted only after all heat treatments have been completed and the hydrostatic tests have passed. Painting can be applied to the welded areas only after the quality inspection of the equipment and pipeline welds is satisfactory. Before applying the primer, special areas such as assembly fits, welding grooves, and threads should be saturated to prevent paint from being applied there. 2.2 Metal Surface Treatment 2.2.1 Classification of Initial Rust on Steel Surfaces The initial rust on steel surfaces is classified into four grades: A, B, C, and D. Grade A refers to a steel surface that is completely covered with scale with almost no rust present. Grade B: A steel surface that has suffered rusting, with some of the oxide scale having peeled off. Grade C: A steel surface whose oxide scale has peeled off or can be scraped off due to rusting, with minor pitting. Grade D: A steel surface whose oxide scale has completely peeled off due to rusting, and where pitting has occurred extensively. 2.2.2 Quality grade of rust removal on steel surfaces: When rust removal is carried out manually or with power tools, the quality of rust removal on the steel surface should reach St2 or St3 level; when rust removal is done by spraying or jetting, the quality should reach Sa1, Sa2, or Sa21/2 level. St2: Complete manual and power tool rust removal. The surface of the steel is free from visible grease and dirt, as well as any loosely attached scale, rust, paint coatings, or other contaminants. Oxide scale, rust, and old coatings that remain adhered to the surface of the steel and cannot be removed with a dull putty knife can be retained. St3 is a very thorough manual and power tool rust removal. The surface of the steel is free of visible oil and dirt, as well as any loosely attached scale, rust, paint coatings, or other contaminants. The rust removal should be more thorough than that for St2, and the surface of the exposed substrate should have a metallic luster. Sa1: Mild spraying or jetting for rust removal. The surface of the steel is free of visible oil and dirt, as well as any loosely attached scale, rust, paint coatings, or other contaminants. Sa2: Complete blasting or jetting for rust removal. The surface of the steel is free of visible oil and dirt, and attachments such as scale, rust, and paint coatings have been largely removed; any remaining residues should be firmly attached. Sa21/2: Very thorough spray or blast rust removal. The surface of the steel shall be free from any visible deposits such as grease, dirt, scale, rust, or paint coatings; any remaining traces shall be only minor discolorations in the form of spots or streaks. 2.2.3 Surface treatment of steel materials: To ensure good adhesion between the surface of the steel material and the coating, as well as to enhance its corrosion-resistant properties, the surfaces of metal equipment, pipes, and other steel components must undergo the following treatments prior to painting: (1) Removal of oil stains. There are various methods for removing oil stains from steel surfaces, including solvent-based methods, alkali solutions, electrochemical methods, and emulsion methods. (2) Removing old paint: The methods for removing old paint from the surface of steel include mechanical methods, alkali dissolution methods, organic solvent methods, and flame rust removal methods. (3) Rust removal: Methods for removing rust from the surface of steel include manual methods, mechanical methods, flame rust removal, chemical cleaning, and electrochemical methods. After the surface treatment of the steel for equipment and pipelines, inspection is required to assess the treatment grade. It shall meet the surface treatment grade for steel specified in GB8923—88 \"Grade of Rust on Steel Surfaces before Painting\". All surface treatments shall have a primer applied within 6 hours after treatment. If the steel surface has not been coated with primer promptly after surface treatment and is left overnight (or if new rust appears on it), the surface treatment should be repeated before applying the primer. 2.3 Corrosion protection of above-ground equipment and pipelines 2.3.1 Selection of coatings The corrosion protection coatings for above-ground equipment and pipelines are detailed in Table 2.3.1. http://www.zgcsg.com/jishuziliao/42.html
1.2.1 Scope of application
(1) Thermal insulation is applicable when the temperature of equipment/pipelines is ≥50°C, and the heat loss meets the requirements specified in GB8175—87. (2) When required by the process, thermal insulation can be applied when the temperature of equipment/piping is ≤50°C. (3) For uninsulated equipment/pipes with a surface temperature of ≥60°C, insulation to prevent burns should be installed in the following areas at those parts that require regular maintenance and for which no other measures can be used to prevent burns. (a) The height above the local or working platform is less than 2.1 m. (b) Within 0.75m of the platform or walkway edge. (4) The following equipment and components do not require insulation. (a) Fans, compressors. (b) Expansion joints, hoses, rotating machines, slide valves, and other similar mechanical equipment. 1.2.2 Design (1) The design standards shall be in accordance with GB50264—97 and GB8175—87. (2) Calculate the insulation thickness based on the fluid temperature. (a) Usually the operating temperature of the fluid. (b) Use the design temperature when heat loss requirements apply. (c) When the actual temperature is unknown, the temperature of the corresponding saturated steam can be used. (3) The insulation thickness shall be specified by the project. (4) The heat protection thickness shall be specified by the project. 1.3 Cold insulation 1.3.1 Scope of application (1) Cold insulation is applicable to equipment/pipelines at ≤5°C, except in cases where heat absorption is required. (2) Cold insulation is suitable when the temperature of the equipment/pipes is ≥5°C but lower than the ambient temperature, mainly to prevent surface condensation. Condensation can lead to the following hazards: (a) Condensate can pose electrical hazards. (b) Condensation will damage the equipment. (3) Above-ground water pipelines and buried water pipelines at the freezing line must comply with the design requirements. (4) The insulation thickness table shall be specified by the project. (5) The anti-freezing thickness table shall be specified by the project. 1.4 Selection of Insulation Materials 1.4.1 Performance Requirements for Insulation Layer Materials (1) Insulation layer materials should be selected from those that provide equations or charts relating the thermal conductivity to temperature changes. For loose or compressed thermal insulation materials, products whose equations or charts for thermal conductivity at the intended service density are available should be selected. During the feasibility study and preliminary design phases, when performing thermal insulation calculations, the data specified in Appendix A of GB50264—97 “Code for Design of Thermal Insulation Engineering for Industrial Equipment and Pipelines” regarding the properties of commonly used thermal insulation materials may be utilized. (2) During operation, when the average temperature of the thermal insulation material is below 350°C, its thermal conductivity shall not exceed 0.12 W/(m·°C); when the average temperature of the heat-insulating material is below 27°C, its thermal conductivity shall not be greater than 0.064 W/(m·°C). (3) The density of the rigid insulation material shall not exceed 300 kg/m3 ； The density of soft materials and semi-rigid products shall not exceed 200 kg/m3 ； The density of the insulation material must not exceed 200 kg/m3. (4) The compressive strength of the rigid materials used for insulation shall not be less than 0.4 MPa ； The compressive strength of rigid materials used for cold preservation must not be less than 0.15 MPa. (5) The moisture content of the insulation material shall not exceed 7.5% (by weight; the same applies hereinafter) ； The moisture content of the insulation material must not exceed 1%. (6) The insulation layer material should be selected from products that can provide certification of having the permissible operating temperature, as well as non-flammability, flame retardancy, and combustibility properties ； For insulation materials, test certificates for water absorption, moisture absorption, and water repellency are also required. For rigid thermal insulation materials, data on the linear expansion or contraction rate of the material must also be provided. (7) The insulation materials used in contact with the surface of austenitic stainless steel shall comply with the regulations regarding chloride content specified in the \"Code for Construction and Acceptance of Insulation Works for Industrial Equipment and Pipelines\" (GB50185). Rigid insulating materials should not be used in vibrating pipes. (8) Depending on the different external surface temperatures of the process equipment and pipelines to be insulated, the combustion properties of the insulation material shall meet the combustion grade specified in the current **standard \"Method for Classifying the Combustion Properties of Building Materials\" (GB8624), and shall comply with the following requirements: (a) When the external surface temperature T0 of the equipment and pipelines to be insulated is greater than 100°C, the insulation material shall meet the performance requirements of Class A non-combustible materials. (b) When the outer surface temperature T0 of the insulated equipment and pipelines is less than or equal to 100°C, the insulation material must meet the performance requirements of flame-retardant Class B1 materials. (c) When the surface temperature T0 of the insulated equipment and pipes is less than or equal to 50°C, foam plastic insulation materials with a protective layer shall meet the performance requirements of materials classified as generally flammable, grade B2. 1.4.2 Performance requirements for waterproofing layer materials (1) The waterproofing layer materials should be those that possess resistance to steam penetration, water drainage capabilities, and moisture resistance, with a water absorption rate of no more than 1%. (2) The flammability of moisture barrier materials shall comply with the provisions of Clause 3.1.8 in GB50264—97 “Code for Design of Thermal Insulation Engineering for Industrial Equipment and Pipelines”. (3) The material for the moisture barrier should be one with stable chemical properties, that is non-toxic and corrosion-resistant, and it must not cause corrosion or dissolution of the materials used for the insulation layer and the protective layer. (4) The material for the moisture barrier should be one that does not soften, blister, or flow in summer, and does not become brittle, crack, or peel off when used at low temperatures. (5) For coating-type moisture-proofing materials, the softening temperature should not be lower than 65°C, and the adhesion strength should not be less than 0.15 MPa ； Volatile matter shall not exceed 30%. 1.4.3 Performance requirements for insulation layer materials: (1) The material used for the protective layer should have high strength; it must not soften or crack at the operating temperature, and it should also be resistant to aging. Its service life should be at least equal to the designed service life. **For critical projects, the designed service life of the insulation and protective layer materials should be more than 10 years. During cold storage, it should last for 12 to 18 years. (2) The protective layer material should possess properties such as water drainage, moisture resistance, resistance to atmospheric corrosion, and good chemical stability ； It shall not cause corrosion or dissolution of the moisture barrier or insulation layer. (3) The protective layer material should be made of non-flammable or flame-retardant materials. However, the protective coatings of equipment and pipelines used for storing or transporting flammable and explosive materials, as well as the pipelines adjacent to them, must be made of non-combustible materials. 1.4.4 Main performance requirements for adhesives, sealants, and wear-resistant materials: (1) Adhesives used for thermal insulation should maintain their adhesive properties within the low-temperature range of use; their adhesive strength at room temperature should be greater than 0.15 MPa, and their softening temperature should be above 65°C. The adhesive used for foam glass should have an adhesive strength greater than 0.05 MPa at -196°C. (2) The adhesives, sealants, and wear-resistant materials used shall not cause corrosion of the metal walls nor lead to the dissolution of the insulation material. Under conditions of expansion and vibration, the wear-resistant agent should prevent foam glass from being damaged due to friction with itself or with metals. (3) Adhesives and sealants should be selected such that they have a short curing time, good sealing properties, and do not crack over the design service life. 1.4.5 Insulation calculations can be carried out in accordance with Article 4 \"Insulation Calculations\" in GB50624—97 \"Design Code for Insulation of Industrial Equipment and Piping\", or by referring to other relevant standards. 1.5 Types of Insulated Structures 1.5.1 Based on different insulation materials and construction methods, they can be roughly divided into ten categories: (1) Clay structures. (2) Filling structure. (3) Bundling structure. (4) Winding structure. (5) Precast opening structure. (6) Prefabricated structure. (7) Irrigation structure. (8) Coating structure. (9) Metal reflective structure. (10) Detachable structure. 1.6 Types of protective layers 1.6.1 Based on the materials used and the construction methods, they can be divided into three categories: (1) Coated protective layers. (2) Metal protective layer. (3) Felt-based protective layer. (4) Others. 1.7 Insulated Structures 1.7.1 The selection of an insulated structure generally should be based on insulation or cooling materials, protective layer materials, as well as various conditions and requirements; however, the following points should also be taken into consideration. (1) A certain mechanical strength is required; the insulation structure should not detach under its own weight or due to external impacts. (2) The insulation structure is simple, easy to construct, and easy to maintain. (3) The outer surface of the insulated structure is neat and aesthetically pleasing. (4) The economic insulation structure refers to the fact that the insulating material is an \"economical\" one; an economical thickness and an economical outer protective layer together constitute an economic insulation structure. 1.7.2 For detailed construction drawings of adiabatic structures, reference may be made to CD42B1—84 “General Atlas for Thermal Insulation (50–600°C)”, CD42B2—84 “General Atlas for Cryogenic Insulation (+10 to -200°C)”, and Volume 4 of the “Construction Drawing Atlas for the Installation Design of Process Piping in Petrochemical Plants”, titled “Insulation for Pipes and Equipment”. 1.8 The construction and acceptance of insulation works shall be carried out in accordance with GB50185-93 \"Code for Construction and Acceptance of Industrial Equipment and Pipeline Projects\". 2 Coating for Corrosion Protection of Equipment and Pipelines 2.1 Overview To prevent corrosion of metals caused by industrial atmospheres, water, and soil, painting the exterior of equipment and pipelines is one of the important anti-corrosion measures in chemical enterprises. (The contents discussed in this section do not include other anti-corrosion methods such as cathodic protection.) Equipment, pipes, supports, platforms, railings, ladders, etc., made of carbon steel, low-alloy steel, or cast iron should generally be painted for corrosion protection. Non-ferrous metals such as aluminum, copper, and lead, austenitic stainless steel, galvanized surfaces, cathodically protected surfaces, metal surfaces coated with fire-resistant cement, as well as plastic and plastic-coated surfaces shall not be painted. Non-standard equipment, pipelines, and associated steel structures manufactured in the factory should be coated with two layers of anti-corrosion primer before leaving the factory (as specified by the manufacturer), with a topcoat being applied at the construction site. Equipment, pipes, and ancillary steel structures assembled at the construction site shall be painted on site. For equipment coated with paint by the manufacturer, if the paint is damaged during transportation, the damaged areas should be repainted on-site. The surfaces of the equipment’s nameplates and other signs or labels shall not be painted. 2.1.1 The selection of coatings shall follow the following principles: (1) It should be suitable for the operating conditions of the equipment and pipelines ； (2) Corresponding to the materials and surface treatment of equipment and pipelines ； (3) The primer, intermediate coat, and topcoat should be properly matched ； (4) Economically reasonable ； (5) Have the construction conditions. Anti-corrosion work must be carried out in accordance with **, the relevant current industry regulations, and the construction instructions provided by the manufacturers of the anti-corrosion materials. Pressure vessels and pipelines must be painted only after all heat treatments have been completed and the hydrostatic tests have passed. Painting can be applied to the welded areas only after the quality inspection of the equipment and pipeline welds is satisfactory. Before applying the primer, special areas such as assembly fits, welding grooves, and threads should be saturated to prevent paint from being applied there. 2.2 Metal Surface Treatment 2.2.1 Classification of Initial Rust on Steel Surfaces The initial rust on steel surfaces is classified into four grades: A, B, C, and D. Grade A refers to a steel surface that is completely covered with scale with almost no rust present. Grade B: A steel surface that has suffered rusting, with some of the oxide scale having peeled off. Grade C: A steel surface whose oxide scale has peeled off or can be scraped off due to rusting, with minor pitting. Grade D: A steel surface whose oxide scale has completely peeled off due to rusting, and where pitting has occurred extensively. 2.2.2 Quality grade of rust removal on steel surfaces: When rust removal is carried out manually or with power tools, the quality of rust removal on the steel surface should reach St2 or St3 level; when rust removal is done by spraying or jetting, the quality should reach Sa1, Sa2, or Sa21/2 level. St2: Complete manual and power tool rust removal. The surface of the steel is free from visible grease and dirt, as well as any loosely attached scale, rust, paint coatings, or other contaminants. Oxide scale, rust, and old coatings that remain adhered to the surface of the steel and cannot be removed with a dull putty knife can be retained. St3 is a very thorough manual and power tool rust removal. The surface of the steel is free of visible oil and dirt, as well as any loosely attached scale, rust, paint coatings, or other contaminants. The rust removal should be more thorough than that for St2, and the surface of the exposed substrate should have a metallic luster. Sa1: Mild spraying or jetting for rust removal. The surface of the steel is free of visible oil and dirt, as well as any loosely attached scale, rust, paint coatings, or other contaminants. Sa2: Complete blasting or jetting for rust removal. The surface of the steel is free of visible oil and dirt, and attachments such as scale, rust, and paint coatings have been largely removed; any remaining residues should be firmly attached. Sa21/2: Very thorough spray or blast rust removal. The surface of the steel shall be free from any visible deposits such as grease, dirt, scale, rust, or paint coatings; any remaining traces shall be only minor discolorations in the form of spots or streaks. 2.2.3 Surface treatment of steel materials: To ensure good adhesion between the surface of the steel material and the coating, as well as to enhance its corrosion-resistant properties, the surfaces of metal equipment, pipes, and other steel components must undergo the following treatments prior to painting: (1) Removal of oil stains. There are various methods for removing oil stains from steel surfaces, including solvent-based methods, alkali solutions, electrochemical methods, and emulsion methods. (2) Removing old paint: The methods for removing old paint from the surface of steel include mechanical methods, alkali dissolution methods, organic solvent methods, and flame rust removal methods. (3) Rust removal: Methods for removing rust from the surface of steel include manual methods, mechanical methods, flame rust removal, chemical cleaning, and electrochemical methods. After the surface treatment of the steel for equipment and pipelines, inspection is required to assess the treatment grade. It shall meet the surface treatment grade for steel specified in GB8923—88 \"Grade of Rust on Steel Surfaces before Painting\". All surface treatments shall have a primer applied within 6 hours after treatment. If the steel surface has not been coated with primer promptly after surface treatment and is left overnight (or if new rust appears on it), the surface treatment should be repeated before applying the primer. 2.3 Corrosion protection of above-ground equipment and pipelines 2.3.1 Selection of coatings The corrosion protection coatings for above-ground equipment and pipelines are detailed in Table 2.3.1. http://www.zgcsg.com/jishuziliao/42.html
Simply put, it means that after insulating the pipe, you can place your hand on it while it’s in operation
With thermal imaging temperature detection, in indoor environments, a surface temperature of ≤ ambient temperature + 25 degrees Celsius meets the **pipe insulation requirements**