Technical Regulations for Reciprocating Compressors

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1. General Provisions 1.1 Scope 1.1.1 These technical specifications apply solely to reciprocating piston compressor units driven by electric motors; subject to the relevant standards, specifications, and data sheets specified in the contract, they provide key supplementary, emphatic, or restrictive guidelines regarding reciprocating piston compressors and their associated equipment in terms of design, manufacturing, inspection, testing, shipping, scope of supply, performance guarantees, as well as the seller’s drawings and documents. When applying these engineering technical specifications, corresponding adjustments or modifications should be made in accordance with the requirements of the project regarding the units. 1.1.2 These technical specifications do not cover the following reciprocating piston compressors: (1) Modular refrigeration compressor units ； (2) Mobile or single-acting cylinder-type compressor units without crossheads ； (3) Reciprocating piston compressors with an exhaust pressure higher than 31.5 MPa. 1.2 Basic Requirements 1.2.1 The seller shall assume full contractual responsibility for the unit in accordance with the standards, specifications, data sheets required by the buyer, as well as the technical requirements of this project. Multiple options should be available for manufacturers. While ensuring good performance of the unit, its cost should be reduced as much as possible. 1.2.2 In addition to these engineering technical specifications, GB standards shall also be followed. 1.2.3 Any deviation by the Seller from the standards, specifications, data sheets required by the Buyer, as well as from the technical requirements of this project, must be clarified to the Buyer in writing in a timely manner, and such deviations shall only take effect upon the Buyer’s approval. In the event of conflicting provisions, the following priority order shall apply: (1) the contract and its technical annexes ； (2) These technical specifications for the project ； (3) Standards and specifications adopted ； (4) The seller’s quotation. 1.2.4 All parameters shall use the International System of Units (SI). 1.2.5 The language of the seller’s quotation document shall be agreed upon by the buyer and the seller. 1.2.6 The Buyer shall participate in certain inspections and tests of the units supplied by the Seller; however, this does not relieve the Seller of any of its contractual obligations. 1.2.7 The Seller shall provide the Buyer with drawings and documents for review, but the Seller shall bear full responsibility for the units it procures. 1.3 Main reference standards and specifications (all should be the latest versions) (1) API618 Reciprocating compressors for general oil refineries or equivalent standards ； (2) ASME VIII steel pressure vessels ； (3) GB150 steel pressure vessels ； (4) GB151 Steel shell and tube heat exchangers ； (5) IEC electrical design. 　2. Basic Design and Manufacturing 2.1 Overview 2.1.1 The compressor unit designed by the seller shall include the compressor, drive motor, auxiliary equipment, as well as everything necessary to ensure its proper operation over the long term (including electrical and control systems). 2.1.2 The Seller shall coordinate the entire unit (including the compressor, drive machine, power mechanism, and related auxiliary systems) and assume full responsibility, which shall include at least the following: torsional analysis, selection of stationary and rotating equipment as well as power transmission components along with their ratings, the inertial moment required to limit motor current fluctuations, acoustic simulation to control harmful pulsations and vibrations, and review of the piping, foundation, electrical, and instrument control designs within the Buyer’s scope. When the layout of the buyer’s mechanical and electrical equipment interferes with the buyer’s facilities, it shall be determined through mutual consultation between the buyer and the seller. 2.1.3 The compressors provided should feature a rational structure (preferably with a layout of one cylinder per row), appropriate material selection, good dynamic balance performance (symmetrically balanced compressors should be preferred for large and medium-sized compressors), low vibration and noise levels, excellent sealing performance, and a long service life for wear-prone components. 2.1.4 The unit’s performance must meet the requirements and enable it to operate continuously and safely under specified conditions. Its service life is at least 20 years, and continuous operation without interruption is at least 3 years. 2.1.5 The Seller shall answer any inquiries and questions related to the design. 2.1.6 The compression unit (including auxiliary equipment) shall be easy to install, assemble, disassemble, and maintain, and sufficient space and access pathways shall be provided. Fitting marks should be provided at important fitting surfaces. 2.1.7 Unless otherwise specified, the compressor unit shall be suitable for outdoor operation under conditions of frost protection and dust protection. 2.1.8 The components of compressors of the same type should be as interchangeable as possible. 2.1.9 In accordance with the buyer’s process characteristics and the specified flow regulation range, an economical and reliable gas flow control device should be designed, with detailed specifications provided in the quotation. 2.1.10 When the buyer requires oil-free gas, an oil-free lubricated compressor should be used. When the buyer specifies limit values for the oil content in the gas, the seller shall take appropriate oil removal measures and provide detailed explanations. 2.1.11 For oil-free lubricated compressors, the average piston speed should be appropriately reduced (generally it should be less than 4 m/s); for oil-lubricated compressors, the average piston speed can also be determined through negotiation between the buyer and seller based on proven practical experience. 2.1.12 For gases with limits on the final compression temperature, over-temperature alarms and interlocks must be installed; for hydrogen-rich media, when the molecular weight of the medium is 12 or less, the final discharge temperature should not exceed 135°C. When the buyer does not specify a limit value for the discharge temperature, it should be determined through negotiation between the buyer and the seller; it is recommended that this value not exceed 149°C. 2.1.13 The seller shall have verified performance records of compressors of the same type. The prototype can be used only after approval by the buyer. 2.1.14 The buyer shall specify the process parameters for the areas belonging to each party, and the seller shall be responsible for any losses in pressure and flow within the scope of supplies provided by the seller. 2.1.15 When the shaft power of the compressor is greater than 150 kW, a manual turning device shall be provided; when the shaft power of the compressor is greater than 750 kW, an electric or pneumatic turning device shall be provided. 2.1.16 Under any specified operating conditions, the maximum allowable continuous load on the compressor’s piston rod must be greater than the overall load on that piston rod. 2.1.17 At least the following threads shall be rolled threads: (1) Connecting rod bolt threads ； (2) Piston rod thread ； (3) Threads of the coupling bolts subjected to alternating loads. 2.2 Structure 2.2.1 Cylinder 2.2.1.1 The maximum allowable operating pressure of the cylinder shall be at least 10% higher than its rated discharge pressure, or equal to the rated discharge pressure plus 0.17 MPa – whichever is greater. Furthermore, the maximum allowable operating pressure of the cylinder should be at least equal to the set pressure of the specified safety valve. 2.2.1.2 When transporting saturated gases or gases containing liquid, the cylinder shall have reliable continuous drainage mechanisms. 2.2.1.3 The cylinder liner must not come into direct contact with the coolant and must be able to be positioned reliably. When using cylinders without cylinder liners, the wall thickness of the cylinder must have sufficient amount for remanufacturing; after such remanufacturing, it should meet the requirements for use under the highest allowable operating pressure or the maximum permissible continuous load on the piston rod. 2.2.1.4 The design of the cylinder bearings shall prevent misalignment or excessive radial runout of the piston rod during temperature rise and at actual operating temperatures. Pulsation suppression devices shall not be used as cylinder supports. 2.2.1.5 The configuration with cascade cylinders may be used only with the buyer’s consent. 2.2.1.6 The connection between pressure-bearing components such as the cylinder head, the gland for the pressure packing, the clearance chamber, and the valve cover, and the cylinder, shall all be made using double-ended studs. 2.2.1.7 The edges at the intake and exhaust ports of the cylinder and cylinder liner should have their sharp corners rounded off. 2.2.2 Valve 2.2.2.1 The valve design shall be suitable for any gas specified by the buyer in the data sheet, with low loss, timely opening and closing, and minimal shock. 2.2.2.2 The design of the air valves should ensure that the assembled intake and exhaust valves cannot be installed incorrectly or in the wrong direction, and that they will not fall into the cylinder even if the bolts securing them become loose or break. 2.2.2.3 The ends of the valve spring shall be flat and ground, and springs of different heights shall be packaged and labeled separately. 2.2.2.4 The edges of the valve disc should have their sharp corners rounded off. 2.2.2.5 When a pneumatic poppet-type suction valve unloading device is used for air volume regulation with flammable and explosive gases, it shall be designed such that the gas used by the unloading device does not mix with the flammable gases, even in the event that the diaphragm and other components are damaged. 2.2.2.6 When specified, the hardness of the valve seat shall be RC32, and it shall be hardened to a depth of at least 1.6 mm at the surface. 2.2.3 Piston, piston rod, and piston rings 2.2.3.1 The piston rod shall be securely connected to the crosshead and the piston, and its preload shall be controllable. When the piston rod diameter is ≥76 mm, hydraulic and heating methods should be used to tighten the coupling nut, and the piston rod must not rotate. 2.2.3.2 When assembling or disassembling the piston rod, a conical protective sleeve should be installed on the threaded portion of the piston rod that passes through the pressure packing area. 2.2.3.3 The piston support rings should be arranged on both sides of the piston rings as much as possible. When oil-free lubrication is used, the load borne by the support rings made of fluorocarbons shall not exceed 0.035 MPa ； When oil lubrication is used, the load on the support ring shall not exceed 0.069 MPa. 2.2.3.4 The piston rod may be equipped with a tail rod only with the buyer’s consent, and a tail rod sleeve shall be provided. The design and quality of the rod seal should be the same as those of the piston rod seal. 2.2.3.5 The friction surface between the piston rod and the packing shall be hardened, with a hardness value of no less than RC50; the surface roughness Ra value should be 0.2–0.4 μm. After rough machining of the piston rod, ultrasonic testing should be performed, and after finish machining, magnetic particle testing should be carried out. 2.2.4 Airframe, crankshaft, connecting rod, bearings, and crosshead 2.2.4.1 The airframe shall have sufficient stiffness, and the crankcase shall be equipped with safe and reliable ventilation openings. 2.2.4.2 The crankshaft shall be forged as a single piece, but detachable counterweights are permitted. There should be smooth transition radii at the drill holes and the interface changes. 2.2.4.3 The main bearings and crank bearings shall be thin-walled sliding bearings that can be replaced easily. When the nominal rated power of the engine airframe ≤ 150 kW, tapered roller bearings are permitted. However, cylindrical rollers and ball bearings shall not be used. 2.2.4.4 The connecting rod bolts and nuts shall be capable of being tightened and locked reliably and conveniently; the seller shall provide the required tightening load values as well as specialized tools. 2.2.4.5 The crosshead shall be equipped with replaceable and adjustable slip plates, and sufficient lubricant shall be provided for the crosshead pin and slideway. 2.2.5 Isolators 2.2.5.1 The buyer shall specify the structural form of the isolators. For applications with oil lubrication and non-hazardous gases, a short single-chamber design can be used ； For oil-free lubrication and non-hazardous gases, a long single-chamber structure can be used ； For flammable, explosive, or toxic gases, a dual-chamber structure should be used, with its design to be agreed upon jointly by the buyer and the seller. 2.2.5.2 Integral metal covers shall be provided at the openings; the use of non-metallic covers is not permitted. 2.2.5.3 Where possible, crosshead guides should be incorporated into the crankcase as an integral part of its structure during casting. 2.2.5.4 The gas and liquid discharge ports of each component of the isolation element shall be able to withstand a pressure difference of ≥0.07 MPa. If a higher pressure difference needs to be tolerated, the buyer will specify it in the data sheet. 2.2.5.5 The gas and liquid discharge systems for the isolation elements, the cleaning air interfaces, as well as the cooling, lubrication, and gas and liquid discharge interfaces of the stuffing box, shall meet the requirements for safe operation. It can be agreed upon jointly by the buyer and the seller. 2.2.6 Packing 2.2.6.1 The seller shall recommend packing types with proven success. 2.2.6.2 For flammable and toxic media, the leaked gas from the piston rod packing should not be released into the plant area, and it should be recycled as much as possible. The seller shall collect the leaked gas into a main pipe, and the outlet of the main pipe shall be equipped with matching flanges and their fasteners. 2.2.6.3 For oil-free lubrication, when materials based on tetrafluoroethylene are used and the maximum allowable operating pressure of the cylinder is greater than 1.7 MPa gauge pressure, the pressure packing of the piston rod shall be liquid-cooled. 2.2.6.4 For oil-lubricated systems, when materials based on tetrafluoroethylene are used and the maximum allowable operating pressure of the cylinder is greater than 3.4 MPa gauge pressure, the pressure packing of the piston rod shall be liquid-cooled. 2.3.1 Lubrication of the compressor casing 2.3.1.1 A forced lubrication system should be used as much as possible. 2.3.1.2 The forced lubrication system shall at least include: main and auxiliary oil pumps equipped with coarse filters (capable of automatic switching and adjustable oil pressure), an oil cooler, a dual-switchable full-flow fine oil filter, necessary instrumentation and control systems, as well as supply and return oil auxiliary systems. 2.3.1.3 For ordinary babbitt bearing filters, the filtration precision is 40μm or finer. For aluminum or particulate babbitt bearings, the filter precision is 10μm or finer. 2.3.1.4 The compressor may be started only when the oil temperature is above 27°C. When the oil temperature is below 27°C, a removable steam heater (capable of transferring heat via heat transfer oil or similar) or a thermostatically controlled immersion electric heater with a stainless steel enclosure should be installed outside the oil tank; the oil must be heated to 27°C within 12 hours, at the specified minimum ambient temperature. If an immersion electric heater is used, its watt density should not exceed 2.33 W/cm2. 2.3.2 Lubrication of cylinders and stuffing boxes 2.3.2.1 When oil lubrication is used, a forced injection type lubricator with a single plunger and adjustable oil volume per point should be employed; each lubrication point equipped with such a lubricator shall have an observable flow indicator. 2.3.2.2 The injector shall have a fuel storage capacity sufficient to maintain normal flow for 30 hours. If specified, an external heating device with constant temperature control shall be provided, and the watt density shall be less than 2.33 W/cm2. 2.4 Materials 2.4.1 All materials of the compressor unit shall be suitable for the properties of the fluid, temperature, pressure, environmental conditions, and operating conditions. Regarding the selection of materials, unless otherwise specified, the corresponding standards of the seller shall apply. 2.4.2 The castings shall be intact, free from harmful defects such as shrinkage cavities, pores, cracks, oxide scales, and the like. The surface of castings should be cleaned using methods such as sandblasting, shot blasting, and pickling. 2.4.3 The cylinder material shall be selected in accordance with the following conditions or from materials for which the manufacturer has a proven track record. Safety valve set pressure MPaG Material 17.2 Forged steel 2.4.4 The steel plates used for manufacturing pressure vessels shall comply with the provisions of ASME Section VIII or other equivalent standard specifications. All pressure vessel manufacturers must be qualified to manufacture pressure vessels of the corresponding categories. 2.4.5 When the operating temperature is below -20°C, the steel shall undergo Charpy V-notch impact tests at the specified minimum temperature in accordance with the relevant provisions of pressure vessel codes. 2.4.6 When hydrogen sulfide is present in the medium, unless otherwise specified, the hardness of carbon steel and low-alloy steel components shall not exceed RC22, and their yield strength shall not exceed 620 MPa. Welded components shall undergo heat treatment to meet the hardness requirements. The valve disc and spring of the gas valve can have a high hardness. For certain alloy steels, the hardness is not restricted by RC22, and it can be agreed upon by the buyer and seller. 2.5 Nameplates and direction arrows 2.5.1 The nameplates and direction arrows of compressors, drives, and auxiliary rotating machines shall be made of materials that are resistant to rusting, and shall be located in easily visible positions. 2.5.2 The following data shall be clearly displayed on the nameplate: a. Compressor: (1) Manufacturer; (2) Tag number and product name; (3) Machine model and specifications. b. Oil pump: (1) Manufacturer’s name; (2) Model and specifications, product name; (3) Manufacturing serial number; (4) Rated flow rate; (5) Discharge pressure; (6) Hydrostatic test pressure; (7) Date of manufacture. c. Pressured vessel: (1) Manufacturer’s name and manufacturing license number; (2) Manufacturer’s identification number for the vessel along with its product name; (3) Design pressure; (4) Maximum allowable operating pressure; (5) Test pressure (for heat exchangers, this should be specified for both the tube side and shell side); (6) Baffle spacing (only for heat exchangers); (7) Vessel category; (8) Weight and main materials; (9) Capacity (heat exchange area, volume, etc.); (10) Date of manufacture. d. Other auxiliary devices: (1) Manufacturer’s name; (2) Serial number; (3) Capacity; (4) Model and specifications; (5) Date of manufacture. 3. Auxiliary equipment 3.1 Drives and power transmission 3.1.1 The power indicated on the motor’s nameplate shall be at least 110% of the maximum power required by the compressor under all specified operating conditions (including losses in the transmission mechanism and couplings); this value may also be determined by the buyer and seller based on verified experience. 3.1.2 The buyer shall specify the electric machine model, relevant requirements, and standards to be followed. 3.1.3 The coupling shall be capable of withstanding the maximum torque as well as the maximum torque variations. The half couplings on the drive shaft shall be supplied as part of the complete set by the compressor manufacturer. 3.1.4 The main and auxiliary motors shall meet the requirements of electrical area classification. For large motors that require positive pressure ventilation, the main motor cannot start when the ventilator is not operational and the air pressure is below the specified value. The air supply for positive pressure ventilation should be located in an area free of flammable and explosive gases. The seller shall provide detailed descriptions and illustrations of the external dimensions and installation dimensions of the ventilator, the dimensions of all connections, and the specifications of the ventilation ducts. 3.1.5 All exposed rotating parts (such as couplings, flywheels, etc.) shall be equipped with guards; in flammable and explosive environments, spark-free guards shall be used. 3.1.6 The use of V-belt drives is permitted only with the buyer’s approval, and this is limited to output powers of 150 KW or less; moreover, the rate of speed change shall not exceed 3% of the compressor’s operating speed. When used in hazardous areas, anti-static devices should be installed. V-belts should be oil-resistant. The use of flat belt drives is not permitted. 3.1.7 The seller shall provide the power capacity of the electrical control cabinet so that the buyer can design the cables. 3.2 Base Plate 3.2.1 If the use of a base plate is specified, the base plate along with its leveling screws, foundation bolts, connection bolts, nuts, washers, shims, etc., shall be provided by the seller. The base plate should have sufficient strength and stiffness. 3.2.2 The exposed edges and corners of the base plate shall have rounded corners of at least R50mm. 3.3 Instruments and Control 3.3.1 The instruments and control systems of the compressor unit shall ensure the safe and reliable start-up, operation, and shutdown of the unit. 3.3.2 Gas volume regulation is generally achieved by using a poppet suction valve or an auxiliary clearance volume; the two methods can also be combined. However, regardless of the method used, it is recommended to install a certain number of bypass systems as well. The above can be specifically agreed upon by the buyer and seller. 3.3.3 The air volume control system can be operated by pneumatic control, electrical control, or hydraulic control. Its operation can be automatic, manual, or programmatically controlled. The buyer shall select one of the above methods and negotiate with the seller; the buyer shall also specify the control range and the source of control signals. 3.3.4 The instrumentation and control systems shall be supplied as a complete set with the main unit, and shall meet the requirements for on-site monitoring and local centralized control. If specified, important parameters should be available for DCS monitoring. 3.3.5 The Seller shall provide the model, specifications, quantity of the main instruments, as well as the recommended manufacturers capable of ensuring quality, subject to the Buyer’s approval. 3.3.6 Electronic or electric instruments shall be suitable for the specified electrical area classification. 3.3.7 The signal interlocking control system shall use a PLC, which shall be installed within the dashboard; its hardware configuration should have a 20% margin. 3.3.8 Where specified, local pressure gauges and local temperature indicators shall be of the anti-vibration type. 3.3.9 The pressure gauge shall be able to resist the erosion of the compressed medium. 3.3.10 The seller shall specify the power supply specifications and required power for the complete set of instruments. 3.3.11 Each compression unit shall be equipped with an independent control panel, and the instruments installed on this panel shall include at least the following monitoring functions. (1) Pressure at the inlet and outlet of process gas at each stage (2) Lubricating oil pressure after the oil filter (3) Pressure in the main pipes at the inlet and outlet of cooling water (4) Temperature at the inlet and outlet of process gas at each stage (5) Gas temperature in the cooler (if required) (6) Temperature of the main radial bearing (7) Temperature of the main motor bearings and the stator (8) Temperature of lubricating oil at the inlet and outlet (at the compressor body) (9) Temperature of the piston rod packing (if required) (10) Alarm buzzer (11) PLC system (12) Pressure of instrument air (if available) 3.3.12 The instruments installed locally on each compressor unit shall include at least the following: (1) Outlet pressure of the main lubricating oil pump (2) Outlet pressure of the auxiliary lubricating oil pump (3) Pressure difference across the lubricating oil filter (4) Oil pressure at the inlet and outlet of the lubricating oil cooler (5) Water temperature at the inlet and outlet of the oil cooler (6) Outlet temperature of the cooling water for the piston rod packing (7) Vibration switch at the compressor body (if specified) (8) Limit switch for the barring gear (9) Pressure transmitter (10) Level transmitter (11) Probe for measuring piston rod sinking (if specified) 3.3.13 Each compressor unit shall be equipped with at least the following alarm and shutdown functions: Alarm Shutdown (1) High final exhaust pressure of the compressor × (2) Low inlet pressure at the first stage of the compressor × × (3) High exhaust temperature at each stage of the compressor × (4) Low lubricating oil pressure × × (5) High pressure drop across the oil filter × (6) Failure to start the auxiliary oil pump × (7) Excessive vibration of the compressor (if specified) × (8) Excessive sinking of the piston rod (if applicable) × (9) High temperature of the main bearings of the compressor × (10) High temperature of the piston rod packing × (11) High liquid level in the inter-stage gas-liquid separator × × (12) High temperature of the stator of the main motor × (13) The barring gear is not disengaged from the main machine × Main motor cannot start (14) High liquid level in the first-stage suction separator × × (15) Low positive pressure ventilation pressure at the collector area of the main motor; main motor cannot start 3.4 Safety Valves 3.4.1 Safety valves shall be installed on the outlet pipelines of each stage of the compressor. 3.4.2 The set pressure of the safety valves shall not be higher than the maximum allowable operating pressure, nor shall it be lower than the requirements specified in API618 standards. 3.4.3 The design of the safety valve shall be carried out in accordance with the specifications agreed upon by both the buyer and the seller. 3.5 Pipeline System 3.5.1 The seller’s pipeline system shall include pipelines, valves, orifice plates (if necessary), thermometers, pressure gauges, sight glasses, insulation covers, and all related accessories. 3.5.2 As specified, the seller shall install separators, coarse filters, silencers, etc., on the inlet pipeline of the first stage of the compressor. 3.5.3 The piping system should feature low vibration, ease of maintenance and cleaning, and easy removal of residual gas and liquid. 3.5.4 During the design of the piping diagrams, the seller shall conduct timely technical coordination with the buyer to avoid conflicts with the buyer’s design scope. 3.5.5 The Seller shall provide matching flanges and their fasteners at all interfaces within the boundary area. 3.5.6 The lubricating oil pipelines and fittings downstream of the filter shall be made of stainless steel. 3.5.7 The corrosion margin for carbon steel and low-alloy steel shall be at least 1.5 mm. 3.5.8 Pipe supports shall have sufficient stiffness, and each support point shall be located at the most effective position for vibration resistance. 3.5.9 All steel pipes shall undergo pressure testing in the manufacturer’s workshop. 3.6 Auxiliary Equipment 3.6.1 Coolers 3.6.1.1 The design conditions for coolers shall comply with the buyer’s utility requirements; process gas coolers shall be designed in accordance with GB151 Class I. The oil cooler is designed in accordance with GB151 Class II. 3.6.1.2 The fouling coefficient on the coolant side should have a certain safety margin. 3.6.1.3 In the case of a shell-and-tube process gas cooler, its tube bundle shall be of a detachable design, and all gas passages shall be easily accessible for inspection and cleaning. 3.6.1.4 For oil coolers with a heat exchange area greater than 0.46 m2, the tube bundle shall be detachable; U-bend type tubes are not permitted. The coolant should flow through the tube side. 3.6.1.5 The lubricating oil pressure at the outlet of the oil cooler shall be higher than the pressure of the coolant provided by the buyer. 3.6.1.6 The cooler design should facilitate inspection and maintenance. 3.6.1.7 Other types of coolers than shell-and-tube coolers may be used only with the buyer’s consent. 3.6.2 Gas-liquid separator 3.6.2.1 The gas-liquid separator shall be equipped with a safe and reliable liquid discharge system. The upper limit of the pressure rating for its installation shall be agreed upon jointly by the buyer and the seller. 3.6.2.2 The gas-liquid separator shall be equipped with a high liquid level alarm, as well as separate connections and level switches for interlock purposes in accordance with API13.8.6.C. There should be a capacity gap of at least 5 minutes between the high liquid level alarm and the interlock. 3.6.3 Pulsation suppression devices 3.6.3.1 The seller shall design in accordance with the approximate design method for pulsation and vibration control specified in API618 standards. 3.6.3.2 The pulsation suppression device should be installed as close as possible to the cylinder, and measures should be taken to prevent the accumulation of condensate. 3.6.3.3 As a minimum requirement, the strength, structural design, and manufacturing of the pulsation suppression device shall comply with GB150, and the influence of alternating loads shall be taken into account in the structural design. When specified in the data sheet, the pulsation suppression device shall also be marked in accordance with ASME codes and registered with the relevant **authoritative authority. 3.6.3.4 The corrosion allowance for the pulsation suppression device is 3.2 mm. 3.6.3.5 The seller shall provide a safe and reliable pulsation suppression device together with a support system for its piping. 3.6.3.6 All butt welds shall pass 100% radiographic inspection. 3.6.3.7 When necessary, pulsation suppression devices shall be installed at the inlet and outlet of each cylinder stage of the compressor. 　4. Inspection and Testing 4.1 The hydrostatic test pressure for the cylinders shall be 1.5 times the maximum allowable operating pressure, but shall not be less than 0.14 MPaG. 4.2 The hydrostatic test pressure for the cylinder cooling jacket and gland packing shall be 1.5 times the specified pressure of the coolant, but shall not be less than 0.8 MPaG. 4.3 The hydrostatic test pressure for pipelines, pressure vessels, filters, and other pressurized components shall be 1.5 times the maximum allowable working pressure or as specified in relevant codes, but shall not be less than 0.14 MPaG. 4.4 The buyer shall specify the scope of participation by the buyer’s personnel in inspection and testing procedures, such as compressor, drive machine, and mechanical operation tests carried out at the manufacturer’s site. The seller shall notify the buyer in writing, two weeks prior to the testing, of the dates and detailed contents of the inspection and testing. The buyer will send personnel in accordance with the contract to participate in the seller’s inspections and tests. 4.5 Other contents and methods of inspection and testing may be added in accordance with the provisions of relevant standards and specifications as well as the requirements of the buyer. 　5. Painting: The requirements for paint can follow the manufacturer’s standards, or the buyer may specify relevant requirements; however, the main and auxiliary equipment (including electrical and instrumentation devices) should preferably use uniform color codes. 　6. Packaging and Shipping 6.1 Packaging and shipment shall comply with the specified shipping requirements. 6.2 The seller shall package in accordance with the specified shipping requirements. Starting from the time of shipment, it must be ensured that the unit can be stored outdoors for at least 6 months. If a longer storage period is required, the buyer and seller may agree on it separately. 6.3 All warranties shall be suitable for sea and land transport. The packaged items shall be properly protected to avoid damage, spoilage, and rusting during shipping. 6.4 All packaging must comply with the transportation restrictions during transit. 6.5 The shipment of the unit shall be carried out only after inspection, testing, and acceptance are completed, and with the buyer’s approval. 6.6 Each packing box shall have two packing lists, one inside the box and one attached outside the box. 6.7 Each packing box shall have clear and durable marking instructions, such as the upward orientation, lifting points, weight, external dimensions, etc. 　7. Marking 7.1 All detachable components shall have corresponding fitting markings. 7.2 Materials, accessories, etc., shipped separately from the main unit shall have labels or markings corresponding to those of the main unit. 　8. Drawings and documents: The seller shall provide 4 sets of drawings and documents for quotation and approval ； 8 sets of final drawing documents, including 6 copies and 2 reproducible versions. 8.1 The following Category A documents are the drawings and materials provided by the seller for the buyer’s reference and technical exchange ； Category B documents shall be provided within the 6th to 8th weeks after the contract comes into effect, so that the buyer can use them for the design of construction drawings ； Category C documents shall be provided in the 16th week after the contract comes into effect ； Category D documents shall be provided at the time of delivery. 8.1.1 Category A documents: (1) Commercial terms and effective prices; (2) Delivery dates and conditions; (3) Complete data sheets and specification tables; (4) Expected performance and performance guarantee values; (5) Inspection items and procedures for the unit at the manufacturer’s site; (6) Items and standard specifications for manufacturing, inspection, and testing; (7) Preliminary P&I diagram of the unit; (8) Preliminary layout drawings (including various dimensions, positions, and boundary markers related to the buyer); (9) Principles for selecting instruments, description of control levels, description and schematic diagrams of protection systems; (10) Scope of work and delivery responsibilities of the seller; (11) Samples (including design manuals for the machinery); (12) Total energy consumption, including water, electricity, steam, oil, etc.; (13) List of subcontractors along with prices of their machinery and equipment, along with lists of the corresponding manufacturers; (14) Deviations from these technical specifications; (15) Performance records under similar or equivalent conditions; (16) Main structural features and key node diagrams of compression and major auxiliary equipment, such as seals and bearings; (17) Preliminary civil foundation drawings; (18) Material list for major components of the unit; (19) List of spare parts recommended by the seller for commissioning and two years of operation.

8.1.2 Category B documents: (1) Foundation drawings for all machinery and equipment, along with design load data (including static and dynamic loads, allowable vibration levels for foundations, etc.); (2) Forces, moments, and displacements that the main connection points of the unit can withstand in the X, Y, and Z directions; (3) Tables of utility requirements and consumption rates; (4) List of instrument equipment; (5) Outline drawings of instrument panels, front layout diagrams, and back wiring diagrams; (6) Wiring connection diagrams for on-site instrument panels and control panels; (7) Schematics of alarm and interlock systems along with set values; (8) Schematics for motor control, external wiring diagrams, and layout diagrams of electrical control boxes; (9) Dimensions, grades, and orientation diagrams of various interfaces; (10) Information on interface types, connection surfaces, grades, dimensions, and materials; (11) Finalized P&I diagrams, outline drawings, and layout diagrams; (12) Maximum weight and maintenance weight of the unit and its equipment; (13) Forces, moments, deflections, and their points of application on the foundation, as well as the center of gravity of the unit, both in static and dynamic conditions; (14) Limitations on the dimensional sizes of the unit’s foundation, as well as dimensions and positions of grooves, holes, anchor bolts, and embedded components; (15) Thickness, location, and material requirements for the secondary grouting layer; (16) Standards and specifications to be followed.

8.1.3 Category C documents: (1) Design calculations for machinery and equipment (if specified); (2) Assembly drawings, sectional views, and installation drawings of the machinery; (3) Structural drawings and installation drawings of auxiliary equipment; (4) Component drawings of wear-prone parts, along with information on materials and special requirements; (5) Detailed piping layout diagrams, positions of pipe supports, calculation data for support forces, and types of supports. (Including all connection and spare interfaces) (6) Lubricating oil requirements and specifications for the unit, lubricating oil system diagram (7) Motor junction box (8) Procedures for assembling and disassembling the unit 8.1.4 Category D documents (1) Material test reports (for main load-bearing components) (2) Seller’s inspection reports and certificates (3) Test reports completed at the seller’s factory (4) Unit acceptance procedures (5) Procedures for flushing the unit’s pipelines and oil system (6) Installation, operation, and maintenance manuals (7) Rust prevention methods (8) List of spare parts (9) List of special tools (10) List of sealing elements (11) List of lubricating oil grades, viscosity, and other specifications (12) List of instruments, instrument installation manuals (13) Supply list. (Including equipment, materials, etc.) (14) Provide relevant parameters, documents, and a list of drawings. (15) Product certification and quality certificates, as well as the final product drawings; additionally, a certificate issued by the quality inspection agency of the labor department confirming compliance with safety and quality standards in manufacturing. (16) Calculations regarding the strength of pressure vessels, along with drawings showing the actual thickness, design thickness, inspection intervals, inspection methods, etc. 8.2 Technical coordination meetings will be held within the third week after the contract comes into effect. 　9. Performance guarantees: The seller shall provide the following guarantees for the compressor unit: 9.1 The compressor unit shall operate safely and smoothly under all specified operating conditions. 9.2 The required volumetric flow rate shall have no negative deviation. 9.3 The deviation of the compressor shaft power is +3%. 9.4 The noise level of the compressor unit shall not exceed 85 dB(A) (at a distance of 1 meter from the unit). 9.5 The effective value of the mechanical vibration velocity of the compressor unit shall not exceed the value specified by the buyer; for large and medium-sized units, this value shall not be greater than 4.5 mm/s. 9.6 The seller shall ensure that the continuous service life of the following vulnerable components is as follows: (1) Piston rod pressure packing and oil scrapper rings ≥ 8,000 hours; (2) Main bearings of the compressor frame and bearing shells at the piston rod ends ≥ 8,000 hours; (3) Piston rings and guide rings ≥ 8,000 hours; (4) Intake and exhaust valve plates and springs: ≥ 8,000 hours when P ≤ 10 MPa, and ≥ 4,000 hours when P > 10 MPa. 10. Others 10.1 Seller’s scope of supply for reference 10.1.1 Complete compressor unit, drive motor, and their bases, etc. 10.1.2 This includes all valves, fittings and connectors, air pipelines, oil pipelines, etc., from the flanges of the primary inlet stop valves to those of the final outlet check valves and stop valves. 10.1.3 Suction and discharge buffers for each stage. 10.1.4 Interstage coolers and aftercoolers. 10.1.5 Inter-stage separator and post-separator. 10.1.6 Separate discharge liquid collection tank (if any). 10.1.7 Integrated circulating oil system. 10.1.8 Cylinder and pressure packing oil system (if any). 10.1.9 Inlet pipe filter. 10.1.10 barring device. 10.1.11 Cylinder support. 10.1.12 Excitation cabinet (when it is a synchronous motor). 10.1.13 Local control panels, control cabinets, and their complete set of accessories. 10.1.14 All local indication instruments for the compressor, as well as the primary instruments and their accessories in the control room and DCS (if required). 10.1.15 Local dashboard and all instruments, valves, etc. on it. 10.1.16 Gas and liquid discharge systems for the isolation components and pressure packing of the piston rod. 10.1.17 Foot bolts, nuts, washers, adjustment shims, etc. 10.1.18 Special tools (including hydraulic tightening devices, electric heating devices, etc.). 10.1.19 Spare parts for driving and trial operation. 10.1.20 Spare parts required for normal operation over two years (with itemized prices); where specified, key components in case of failures such as piston rods and cylinder liners should also be included. 10.1.21 Couplings and their guards. 10.2 Reference Design Parameters (provided by the buyer) 10.2.1 Number of operating days per year: 10.2.2 Location of unit installation: Altitude of the user’s location; Indoor/Outdoor; With ceiling/Without ceiling; Partial side walls; Elevation of main units/auxiliary units; Span/Length of the factory building 10.2.3 Site conditions 10.2.3.1 Atmospheric temperature: Annual average temperature; Extreme maximum temperature; Extreme minimum temperature; Average temperature in the hottest month; Average temperature in the coldest month; Outdoor calculation temperature for summer ventilation 10.2.3.2 Humidity: Annual average relative humidity; Average relative humidity in the hottest month; Average relative humidity in the coldest month 10.2.3.3 Air pressure: Annual average air pressure; Average air pressure in summer; Average air pressure in winter 10.2.3.4 Earthquake intensity 10.2.3.5 Average number of thunderstorm days per year 10.2.3.6 Abnormal conditions: Dust; Smoke; Hazardous/Non-hazardous; Others 10.2.4 Conditions for public utilities 10.2.4.1 Circulating cooling water: Supply pressure; Supply temperature; Return pressure; Return temperature; Fouling coefficient; Chloride content; pH value 10.2.4.2 Desalinated water: Supply pressure; Supply temperature; pH value; Oxygen content; Conductivity 10.2.4.3 Instrument air: Pressure; Temperature; Dew point; Quality 10.2.4.4 Nitrogen: Pressure; Temperature; Purity 10.2.4.5 Electricity: Electrical area; Voltage; Number of phases; Frequency; Short-circuit capacity; Power supply for instruments 10.2.4.6 Emergency power supply: Voltage; Number of phases; Frequency 10.2.4.7 Low-pressure steam: Pressure; Temperature; Price of the pump calculation software