Technical requirements for the installation of shims in reciprocating compressors

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Technical requirements for the installation of shims on reciprocating compressors 1. Shim arrangement: At least one set of shims should be placed next to each anchor bolt. Shims should also be placed in areas where the load is concentrated and at the center of the machine’s reinforcement bars. The distance between two adjacent sets of shims should be 300–700 mm. There should be no more than four shims in each group; the thicker ones should be at the bottom, the thinner ones on top, and the thinnest one in the middle. The total height should not exceed that of the secondary grouting layer. 2. Specifications and material of shims: The material of the shims is Q235; their length is twice their width. The length must exceed the center of the anchor bolts by 15–20 mm, with a portion extending beyond the edge of the base. The slope of the inclined shim is 1/20, and its thickness depends on actual requirements and the material used. 3. Contact area of shims: The contact area between the shims as well as between the shims and the base should be no less than 70%, and the local gaps should not exceed 0.05 mm. Levelness and elevation of shims: 1) For shims installed using the grouting method, the levelness deviation should not exceed 0.10/1000, and the shims in each section should be at the same elevation; the allowable elevation deviation is ±1 mm. 2) For the temporary shims installed using the method without shims, the horizontal deviation of their installation should not exceed 0.2/1000, while the allowable elevation deviation is ±2 mm. 4. Inspection of shim gaps: Use a 0.05 mm feeler gauge to check the gaps between the shims as well as between the shims and the machine base. The total length that can be inserted from both sides at the same cross-section of a shim shall not exceed 1/3 of the shim’s length (width). 5. Shim positioning: After alignment, the shims should be fixed in place with welds. Treatment of foundation bolts: The foundation bolts should be vertical; the material, specifications, and quantity of nuts and washers must meet the design requirements. The threads must be undamaged, with 1–3 threads exposed above the nut, and anti-rust grease should be applied. 6. Secondary grouting: Before carrying out secondary grouting, the shims and small screw jacks in each group should be spot-welded in place, and records of their locations, geometric dimensions, and quantities should be kept as part of the concealed work documentation. Some key technical requirements are as follows: The technical requirements for the shims used in the installation of piston compressors should comply with industry standards and the specifications provided in the accompanying technical documents. Here are some key technical requirements: 1. Specifications and dimensions of shims: The specifications and dimensions of the shims must comply with those specified in the accompanying technical documents. In the absence of specific provisions, it shall be manufactured and used in accordance with industry standards, such as those specified in the \"General Specifications for the Construction and Acceptance of Mechanical Equipment Installation Projects GB50231-2009\". 2. Layout of the shims: The shim sets should be placed on both sides of each foundation bolt. When the distance between foundation bolts is less than 300 mm, one set of shims can be placed on the same side of all the foundation bolts. The shim set should be placed below the foundation bolts or the vertical members of the machine, as well as in the areas of the machine’s base that are under the most stress. 3. Height of the shim set: The height of the shim set should be between 30 mm and 70 mm. Each shim set should not consist of more than 4 layers, and thin shims should not be used. When placing flat shims, the thicker ones should be placed at the bottom, while the thinner ones should be placed in the middle and should not be less than 2 mm thick. 4. Leveling of the shim set: The shim set should be placed neatly and steadily, with even contact with the foundation surface; the contact area should be greater than 50%, and the levelness deviation of the top surface of the shim set should be less than 2 mm/m. After the machine is leveled, the shim set should protrude 10 mm to 30 mm beyond the outer edge of the base. 5. Fixing of shims: The overlapping length of paired inclined shims should be greater than 3/4 of their total length, and the angle of deviation between them should not exceed 3°. After leveling the shim set, it should be welded in place using tack welding to ensure the stability of the equipment. 6. Material of shims: The material for shims can be ordinary carbon steel or cast iron. The slope of inclined shims should be between 1/10 and 1/20, while for shims used in vibrating or precision equipment, the slope can be as low as 1/40. 7. Exposure length of shims: The length of the shim set extending into the bottom surface of the equipment base should exceed the center of the equipment’s foot bolts. 8. Installation without shims: In some cases, the installation method without shims may be employed; this requires determining the location and quantity of temporary supports or adjustment screws based on the quality of the mechanical equipment and the structure of its base. 9. Shock-absorbing shims: For equipment that requires shock absorption, shock-absorbing shims can be used, ensuring there is enough margin within their adjustment range; once leveled, the nuts should be tightened. 10. Grouting: The shims and bases should be filled with concrete, but concrete must not be poured into their movable parts to ensure the stability of the shims. When installing a piston compressor, it is necessary to follow the aforementioned technical requirements strictly to ensure the safe and stable operation of the equipment. At the same time, it is also necessary to refer to the specific equipment manuals and relevant standards in order to meet the requirements of particular equipment and operating conditions