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General Provisions 1.1 These regulations apply to the maintenance and repair of steel, steel-lined, stainless steel, and titanium reaction vessels with a working pressure of 0.1–1.6 MPa and a working temperature below 250°C. When implementing these regulations, the \"Regulations on Safety Inspection of Pressure Vessels\" and the \"Inspection Regulations for In-service Pressure Vessels\" shall also be complied with. 1.2 For the maintenance and repair of steel-lined, stainless steel, and titanium reaction vessels with a working pressure of 0.1 MPa or less, their transmission and sealing systems shall be handled in accordance with these regulations; the maintenance and repair of the vessel body and cover shall be carried out as for vessels under normal pressure. 1.3 The maintenance and repair of the motors and reducers associated with it are carried out in accordance with the \"Motor Maintenance and Repair Procedures\" and the corresponding maintenance and repair procedures for reducers. 2 Maintenance Intervals 2.1 Types of Maintenance The types of maintenance are divided into minor repairs, medium repairs, and major repairs. 2.2 Maintenance Intervals The maintenance intervals are shown in Table 1. Table 1: Maintenance Types – Minor Repairs, Medium Repairs, Major Repairs; Maintenance Intervals: 720–900, 5000–6000, 10000–12000. 3 Maintenance Activities 3.1 Minor Repairs 3.1.1 Inspect the flanges and valves, and replace gaskets at leaking points as well as any bolts that are loose. 3.1.2 Inspect manholes and sight glasses, and replace damaged components such as gaskets, sight glasses, and bolts. 3.1.3 Check the sensitivity and reliability of safety accessories. 3.1.4 Inspect, adjust, or replace the drive V-belt. 3.1.5 Inspect, adjust, or repair the sealing device. 3.2 Medium repairs 3.2.1 includes the contents of minor repairs. 3.2.2 Inspect and repair the interior and external jackets of the tank, measure the wall thickness, and repair any local defects. 3.2.3 Repair the external insulation layer of the tank body and lid, and apply paint. 3.2.4 Inspect and repair accessories such as belt pulleys and couplings. 3.2.5 Inspect and repair the mixer and other components. 3.2.6 Inspect, repair, or replace bearing bushings, shaft sleeves, and other components. 3.3 Major Overhaul 3.3.1 includes the contents of the medium overhaul. 3.3.2 Repair the tank body and tank lid, or replace the tank lid. 3.3.3 Repair or replace the jacket and heat exchange tubes. 3.3.4 Inspect and repair the equipment foundation. 3.3.5 Repair or replace components such as tape wheels and couplings. 3.3.6 Repair or replace the mixing shaft and mixer. Repair or replace the sealing device. Q/LSAN J 08604-2004 4 Preparations before maintenance 4.1 Technical documents 4.1.1 Certificate of conformity upon leaving the factory, quality certificates, design calculations for the main pressure-bearing components, installation and operation manuals, etc. 4.1.2 As-built drawings, installation drawings, foundation drawings, assembly drawings, drawings of major components, drawings of vulnerable parts, etc. 4.1.3 Records such as equipment operation, maintenance, faults, and accidents. 4.1.4 Technical inspection records 4.1.4.1 Inspection records of the main geometric dimensions and precision of the tank body and its key parts and components (such as roundness, perpendicularity, taper, straightness, etc.). 4.1.4.2 Defect records of the tank body and components (such as roughness, corrosion, cracks, flaking, scratches, burns, and the bonding strength between the surface material and the substrate). 4.1.4.3 Records of the fit between parts and components (e.g., coaxiality, parallelism, runout). 4.1.5 Develop a maintenance plan; prepare a construction network diagram if necessary. 4.1.6 In the event of design changes, structural modifications, or material changes during maintenance, such changes must comply with the relevant provisions of GB150 \"Steel Pressure Vessels\" and the \"Regulations on Safety Inspection of Pressure Vessels\", and must be approved after review. 4.1 Material Preparation 4.1.1 Main spare parts and components, as well as key materials that need to be replaced. 4.1.2 Lifting equipment, testing tools, and repair tools. 4.2 Safety technical preparations 4.2.1 Remove all materials from the equipment, pipelines, and valves. 4.2.2 Turn off the power supply and hang a “Do Not Operate” warning sign. 4.2.3 Isolate the equipment from the piping network using blind flanges, and install clear isolation markers. 4.2.4 Follow the regulations to complete the hot work procedures. 4.2.5 Scaffolding, portable ladders, and other equipment used for maintenance must be safe and sturdy. 4.2.6 When using toxic coatings for corrosion protection, measures to prevent exposure to toxins must be taken. 4.2.7 When conducting on-site radiographic testing, a protective isolation area shall be established, along with safety signs. 4.2.8 In the case of media that are flammable, oxidizing, toxic, or asphyxiating, it is necessary to carry out displacement, neutralization, disinfection, and cleaning, as well as take samples for analysis; the results of such analysis must meet the requirements specified in relevant codes and standards. 4.2.9 When performing internal maintenance, facilities such as ventilation and safety rescue equipment should be provided. Assign a dedicated person for supervision. 4.2.10 The supply voltage for lighting fixtures and tools used for maintenance shall comply with the provisions of GB3805 <<Safe Voltage>>. 5 Maintenance Methods 5.1 Disassembly 5.1.1 When removing the tank flanges and pipeline flanges, it is necessary to protect the sealing surfaces; they must not be scratched or damaged, and markings should be made on them. 5.1.2 When removing the sealing device, the transmission mechanism shall protect the moving and stationary sealing surfaces as well as the mating surface of the mixing shaft. 5.1.3 During disassembly, the relative positions and fit dimensions between the removed parts and related components should be measured and marked. 5.1.4 Special tools must be used to remove rolling bearings. 5.2 Tank Body and Tank Lid 5.2.1 For the repair of defects in the tank body, tank lid, and jacket, the patching method or welding after grinding can be employed, provided that the requirements of the \"Regulations on Safety Inspection of Pressure Vessels\" and relevant regulations are met. But it is necessary to a. carry out repair processes that comply with relevant regulations (including welding processes) ； b. Welders must hold a welder’s certificate corresponding to the appropriate category ； c. Inspection and flaw detection personnel must hold a qualification certificate for non-destructive testing personnel. 5.2.2 Scratches, dents, and marks on the various joint surfaces of the tank body and tank cover flanges may be repaired by grinding or patch welding. 5.3. Defects in the sealing of the rotating and stationary rings of mechanical seal units can be repaired using grinding methods. 5.4 Agitator Q/LSAN J 08604-2004 5.4.1 Coupling 5.4.1.1 If the inner surface of the coupling is severely rusted, it is permissible to reprocess the mating surface and the inner hole, provided that the strength is not affected. 5.4.1.2 Local pits on the inner surface of the coupling caused by rusting may be repaired by welding, provided that the strength is not affected. 5.4.2 Stirring shaft and impeller 5.4.2.1 If defects (corrosion, wear) occur on the working surface of the stirring shaft, it can be repaired by a method involving spraying followed by mechanical processing. 5.4.2.2 The bending of the mixing shaft can be corrected by pressure. 5.4.2.3 Paddle, anchor, frame, and turbine impellers may be corrected using pressure correction and welding techniques; after correction and welding repair, the inner hole is precision-machined. 5.5 Assembly 5.5.1 Before assembling the equipment, clean all parts and components thoroughly. Check the dimensional accuracy of these parts and components in relation to the areas involved in the assembly; assembly may proceed only after it is confirmed that they meet the required standards. 5.5.2 The assembly of all major relevant components shall be carried out according to the marked positions during disassembly. 5.5.3 During assembly of the mixing shaft, use a dial indicator to check and adjust the circular runout of its sealed shaft section. 5.5.4 Apply sealant inside the stuffing box and on the surface of the shaft’s sealed section, or apply a lubricant suitable for the medium. 5.5.5 The oil-impregnated graphite packing should be installed one piece at a time; the joints should overlap, with an opening slope of 45°. Each layer should be offset by 0°, 180°, 90°, and 270° to prevent the joints from overlapping. 5.5.6 When tightening the packing gland, the bolts should be tightened symmetrically with even force, and the gland and the packing box must be coaxial. 5.5.7 Rolling bearings should be installed by thermal installation, with the oil temperature used for heating them not exceeding 100°C. 5.5.8 The soft material ring of the mechanical seal shall not suffer from chipping or scratches during installation (especially scratches that run through both the inner and outer surfaces). 6 Maintenance Quality Standards 6.1 Tank Body and Tank Lid 6.1.1 The manufacturing and repair of pressure-bearing components such as the tank body and tank lid (including jackets) must comply with the technical requirements specified in the design drawings, as well as the relevant provisions of the \"Regulations on Safety Inspection of Pressure Vessels\" and GB150 \"Steel Pressure Vessels\". 6.1.2 After the stainless steel equipment is manufactured, oil residues should be removed, and it should undergo acid washing and passivation treatment. 6.1.3 The repair and fabrication of titanium equipment shall comply with the provisions of CD130A9 \"Technical Requirements for Titanium Equipment\" and the \"Regulations on Safety Inspection of Pressure Vessels\". 6.1.4 Reactor vessels that, as a result of regular inspections in accordance with pressure vessel regulations, are classified as grade 4 in terms of their safety status, may only be used under monitoring conditions, with replacement required within a specified time limit ； Those rated at level 5 should be scrapped. 6.1.5 For the welding and repair of pressure components, the commonly used electrode grades shall refer to the provisions in Table 2. 6.2. 5.2 Sealing Devices 6.2.1 Packing Sealing 6.2.1.1 The allowable deviation for the center of the holes in the packing box and the packing gland is ±0.6 mm, and the tolerance for the coaxiality of the hole centers with respect to the centerline of their flanges is also 0.6 mm. 6.2.1.2 The fit between the packing gland and the packing box is H11/d11; the holes in the packing gland as well as those in the box