Thread Content
XI. Pressure Test 1. Before conducting a pressure resistance test on the equipment, the following preparatory steps should be taken: 1) The structure of the equipment and its technical requirements must be well understood; 2) For equipment that has already been cleaned and inspected internally, is properly sealed, and shows no issues, there is no need to open it up for further cleaning or inspection; 3) The external connections, gaskets, and fastening bolts of the equipment should be checked to ensure they meet the required standards; 4) When performing a hydraulic test, it is necessary to assess the load-bearing capacity of the foundation, and reliable support and fixation must be in place to prevent accidents or damage to the equipment. 5) An exhaust port should be provided at the highest point of the equipment, so that the air inside can be expelled during liquid filling; 6) The temporary blind plates used for pressure testing must be properly designed to have sufficient strength. 2. Except where the design drawings or technical documents specify that a gas may be used in place of a liquid for pressure testing, gas pressure testing shall not be employed. Before conducting a pressure test, the relevant technical documents should be thoroughly reviewed, and reliable safety measures should be established. The test may only be carried out after it has been inspected and approved by the technical supervisor of the installation unit and the safety supervision department. 3. For equipment whose design requires settlement monitoring of the foundation, when conducting a hydraulic test on the foundation, settlement observations of the foundation shall be carried out at pre-marked measurement points before, during, after fluid filling, and during fluid drainage; furthermore, a “Foundation Settlement Record” must be kept. 4. When conducting a pressure test, two pressure gauges should be installed, one at the highest point and one at the lowest point. The test pressure shall be determined based on the reading of the pressure gauge located at the highest point. When performing a hydraulic test on vertical equipment with it in a horizontal position, the test pressure shall be the vertical test pressure plus the static pressure resulting from the liquid column within the equipment. 5. The maximum scale range of the gauge used for testing should be 1.5–3 times the test pressure; 2 times is the preferred value. The pressure gauge shall be calibrated against a gauge of higher accuracy; the accuracy of the pressure gauge used for pressure testing shall be no less than grade 1.5. 6. During the pressure test, if any abnormal noises, sudden drops in pressure, peeling of paint, or failures in the pressure-applying equipment are detected, the test must be stopped immediately to identify the cause and take appropriate action. 7. The test pressure for the pressure resistance test shall meet the requirements specified in the design drawings or technical documents: for hydraulic testing, it shall be not less than 1.25 times the design pressure; for pneumatic testing, it shall be not less than 1.15 times the design pressure. 8. When the design temperature is higher than the temperature of the test medium, the test pressure is calculated using the following formula: where P is the test pressure in kilogram-force per square centimeter, p is the design pressure in kilogram-force per square centimeter; σ is the allowable stress of the equipment material at the test temperature in kilogram-force per square centimeter, and σ’ is the allowable stress of the equipment material at the design temperature in kilogram-force per square centimeter. The ratio of these allowable stresses shall not exceed 1.8 ； n: Voltage withstanding test coefficient. Hydraulic test: n=1.25; Pneumatic test: n=1. 9. When water is used as the pressure testing medium, clean water should be employed. When testing equipment made of austenitic stainless steel or equipped with an austenitic stainless steel lining using water, measures should be taken to prevent chloride corrosion; otherwise, the chloride content in the water should be kept at no more than 25 ppm. 10. When conducting hydraulic tests on equipment made of carbon steel or 16MnR steel, the temperature must not be lower than 5°C. When conducting hydraulic tests on other low-alloy steel equipment (excluding cryogenic equipment), the liquid temperature must not be lower than 15°C. If the material’s brittle transition temperature increases due to factors such as plate thickness, the temperature of the testing liquid must also be increased accordingly. The hydraulic testing temperature for equipment of other steel grades is specified in the design drawings. 11. When the equipment is filled with liquid, wait until the wall temperature of the equipment equals the temperature of the liquid before gradually increasing the pressure to the specified test pressure. Hold this pressure for 10 minutes, then reduce it to the design pressure and maintain it for at least 30 minutes before conducting the inspection. 12. After the hydraulic test is completed, the pressure should be reduced slowly. When water is used as the pressure testing medium, the water used for testing should be discharged into the drainage ditch. After the liquid has been drained, compressed air or another inert gas should be used to dry the inner surfaces of the equipment. 13. The pneumatic testing of equipment shall comply with the following requirements: 1) The gas used for pneumatic testing shall be dry and clean air, nitrogen, or other inert gases. For equipment that is sensitive to oil or requires moisture protection, oil-free dry gas should be used; 2) For equipment made of carbon steel and low-alloy steel, the temperature of the pressure testing medium should not be lower than a certain value in degrees Celsius, while for equipment made of other types of steel, the temperature must comply with the specifications given in the design drawings; 3) During the pneumatic pressure test, the pressure should be increased gradually to 10% of the specified test pressure, and this level should be maintained for 10 minutes to conduct an initial inspection of all welds and joints. If everything is satisfactory, the pressure should then be increased to 50% of the specified test pressure, and thereafter it should be raised in steps of 10% of the specified test pressure at a time, with each level being maintained for 5 minutes. After that, the pressure should be reduced to the design pressure and maintained there for at least 30 minutes before another inspection is conducted ； 4) The pressure test shall be carried out under the supervision of the relevant safety authorities. 14. For the pressure resistance test of equipment, it is considered pass if the following conditions are met: 1) There are no leaks in the equipment or at any of its welds; 2) The equipment shows no visible abnormal deformation; 3) For high-strength steel equipment that has been repaired and whose weld repair depth is greater than a certain value in millimeters or more than half of the wall thickness, re-inspection of the welded areas using the original flaw detection methods should reveal no defects exceeding the predetermined standards; 4) For equipment for which residual deformation measurement is required according to design specifications, residual deformation should be measured simultaneously during the pressure resistance test. The acceptable standard is a radial residual deformation rate of no more than 0.3%, and this can be measured using a dial indicator or resistive strain gauges on the outer surface of the equipment. XII. Airtightness Test 1. Before conducting the airtightness test, the safety devices, pressure gauges, level gauges and other accessories on the equipment, as well as all internal components, must be fully installed and passed inspection. 2. For equipment undergoing a pressure test, the airtightness test can be carried out simultaneously during the inspection once the pressure from the pressure test has been reduced to the design pressure. 13. Project Acceptance 1. During equipment installation, records of handover should be kept at the end of each key process, along with proof of compliance from the previous process. 2. At the time of equipment handover and acceptance, the construction unit shall submit the following technical documents: 1) The manufacturer’s certificate of conformity for the products, quality certificates, and related technical documents; 2) Equipment acceptance and inventory records; 3) Records of handover for key construction stages; 4) As-built drawings (in accordance with **relevant regulations); 5) Equipment installation records; 6) Records of cleaning and degreasing of the equipment (pipeline) systems; 7) Records of filling the equipment; 8) Records of pressure testing of the equipment; 9) Records of equipment cleaning, inspection, and sealing; 10) Settlement observation records; 11) Notices of design changes and substitution of materials; 12) Other construction-related records.