What safety measures need to be implemented for pipeline pressure testing?

A pressure application plan should be developed, and pressure testing should be carried out in accordance with relevant standards. A safety zone should be established in the area where testing takes place, and unauthorized personnel are prohibited from entering. There have been incidents in the past where pressure gauges failed, resulting in deaths.

There are relevant standards regarding pressure testing; several of these standards are provided for reference. JB/T 9089-1999 | Pressure testing pumps SY/T 6149-1995 | Technical specifications for pressure testing of natural gas transmission pipelines SY 5467-1992 | Specifications for pressure testing of casing strings JB/T 53194-1999 | Electric pressure testing pumps; Product quality grading SY/T 5467-2007 | Specifications for pressure testing of casing strings

During gas pressure testing, the main goal is to prevent overpressure explosions and explosions caused by the combustion of oil and gas

Measures to isolate from the outside world! ! ! ! Instructions must be provided before construction begins! ! !

When testing pipes for pressure, maintain a sufficient safety distance from them. When a pipeline leak is detected, pressure should be released first before carrying out repairs. During tasks such as pipeline inspection and pipeline cleaning, proper personal protection must be ensured; it is strictly prohibited to strike the pipelines, and it is also forbidden to face pressure fittings that pose a high level of risk. When maintaining pipes that carry flammable, explosive, toxic, or similar substances, protective measures must be taken based on the properties of those substances. This includes using concentration detectors, wearing air respirators, protective clothing, anti-static garments, protective gloves, and goggles.

Operating Instructions for Pressure Pipeline Leakage Testing 1 Purpose These regulations are formulated to strengthen the quality management and control of pressure pipeline leakage testing. 2 Scope of Application These management regulations apply to the entire process of quality control for pressure pipeline leakage tests within the company. 3 Responsibilities 3.1 The project’s technical supervisor is responsible for the quality management and control process of pressure pipeline leakage tests. 3.2 The project quality inspector is responsible for the quality management and control process of the pressure pipeline leakage test. 4 Working Procedures 4.1 Leakage test methods: kerosene leakage test, ammonia leakage test. 4.2 Pipeline leakage test: This test is carried out after the pressure pipeline has been installed, once it has passed the inspection, and prior to anti-corrosion treatment; the testing method shall comply with the requirements specified in the drawings. 4.3 A hydrostatic test must be conducted prior to the leakage test, and the leakage test must be carried out only after the hydrostatic test is successful. 4.4 Before the test, the operators and inspectors shall carry out the preparatory work required prior to the test. They should first verify whether the quality records, markings, and visual quality of the test components meet the requirements specified in the drawings, standards, and manufacturing procedures; only after confirming that they are satisfactory can the testing process begin. 4.5 During the testing process, the operators and on-site inspectors must keep accurate original records. Once the testing is complete, a leakage test report shall be filled out, and relevant personnel should sign it. 4.6 Kerosene penetration test: 1) Clean the side of the weld that can be inspected, apply chalk paste to it, and after it dries, apply kerosene to the other side of the weld to ensure sufficient penetration of the surface; it is considered successful if no stains appear on the chalk after half an hour. 4.7 Ammonia leakage test method: 1) Ammonia is a flammable and explosive gas; proper safety measures to prevent fires and explosions must be implemented at the test site. 2) Ammonia is toxic; testers and the testing site must take proper measures to prevent exposure to this gas and to ensure isolation. 3) The ammonia leakage test method should be carried out after the hydraulic test of the container, and contaminants such as oil on the weld surface and its surrounding areas must be removed. 4) Ammonia filling test at 10–30% (by volume) (inspection of welds at the connection between the tubes and tube sheets of heat exchangers). 5) Preparation work: a liquid ammonia pressure cylinder and piping with valves. b Pressure cylinders of inert gases (such as nitrogen) and piping with valves. c Three-way piping, one end of which is an intake pipe with a valve. d Ammonia pressure (vacuum) gauge. e Tank for gutter pipes with overflow. f Discharge line with valve. g Temporary pipeline (or hose) for connecting to external tap water. h Tools such as adjustable wrenches for installation and removal. I use a phenolphthalein solution prepared from 1% phenolphthalein, 50% alcohol, and 50% water, or phenolphthalein test strips. 6) Install and connect A according to the drawings; replace the air in the inflation space with an inert gas such as nitrogen in a quantity 3 to 5 times the volume of the inflation space, until the oxygen content at the outlet is ≤0.5%, in order to prevent the formation of explosive mixtures of ammonia and air (whose explosive limit is 15–18% by volume), and then close the valve on the discharge pipeline. B. Start the vacuum pump to evacuate to a vacuum level of 20 Kpa [608 mm of mercury (absolute pressure)]. C. Based on the relationship between pressure, ammonia concentration, and holding time shown in Table 1, a mixed gas of ammonia and nitrogen at the pressures and concentrations specified in the table is introduced. Table 1: Test pressure (Mpa): 0.15, 0.3, 0.6, 1.0; Ammonia concentration (%): 30, 20, 15, 10; Holding time (hours): 15, 12, 6, 4. D. If vacuum pumping is not possible, ammonia concentration should be measured by sampling, and holding should begin once the specified criteria are met. Note: 1: Increasing the ammonia concentration at the leak detection pressure can reduce the holding time ； If the leak detection pressure or ammonia concentration is reduced, the holding time must be extended. Note 2: The amount of ammonia gas filled is converted into a value representing the total pressure of the ammonia-rich mixture, based on a 15% (by volume) ammonia content in the mixture. E. Apply the leak detection indicator (or test strip) evenly and closely to the tube sheet, and keep it moist at all times. F. Close the vent valve; under the test pressure, maintain the pressure for the duration specified in Table 1. Check once at 0.5 hours and once at 1 hour after the start of pressure maintenance, and then check every 2 hours thereafter, to observe whether any red spots appear on the test strip. G. Once the leak test is complete, carefully and slowly open the valve of the discharge pipeline to allow the water to be drained, being careful not to cause the water in the tank to be blown out due to excessive discharge pressure; tap water should be placed in the small tank in advance. H. When the pressure drops to “0”, open the inert gas line valve and the three-way intake line valve. Replace the air with an inert gas such as nitrogen in a volume 3 to 5 times that of the space, remove the ammonia, and then close the valve. Remove the equipment and instruments used for leak detection, and clean them up. I. Remove the equipment and instruments used for leak detection and clean them up. 7) Method of filling with 1% (by volume) ammonia gas: Compressed air containing 1% by volume of ammonia is introduced into the container; the test pressure is 1.05 times the design pressure. During the test, the test strip is placed in advance on the surface to be inspected (such as the outside of sealing surfaces, welds, etc.), and then the pressure is reduced to the design level to observe whether the test strip changes color. 4.8 An engineering supervisor must be present during the testing process. If the contract requires customers to participate, they must be notified to do so. 4.9 After the test is completed, the quality inspector issues a test report, which is signed for confirmation by the relevant personnel.

Tests can generally be carried out in accordance with relevant standards, but the selection of pumps and valves is based on theoretical calculations along with empirical considerations. Special attention must be paid to the transition points and the calculation of pressure differences at the inlet and outlet; particular care is also required when dealing with sections where liquid accumulates. The outlet size can be increased appropriately. In special cases, it is necessary to install relief valves to prevent water hammer effects