Preparation for installation of GCE gas pressure reducer pipeline

Preparation for installation of GCE gas pressure reducer pipeline

1、 Inspection of pipes and accessories

Before installing oxygen pipelines, quality inspections should be conducted on the pipes and accessories used to check whether the materials, specifications, and technical performance of the pipes and accessories meet the design requirements, whether there is any damage to the appearance, and whether the processing and assembly quality can meet the production needs. Before installation, the valve should undergo an air tightness test at a pressure equal to the working pressure.

2、 Degreasing of pipes and fittings

After passing the inspection, the pipes and accessories need to be degreased. Before degreasing, clean and remove rust from the pipes and accessories. For stainless steel pipes and non-ferrous metal pipes, only the surface and soil inside the pipes need to be cleaned.

The commonly used solvents for degreasing treatment are industrial carbon tetrachloride, distilled alcohol, industrial dichloroethane, etc.

Industrial grade carbon tetrachloride is recommended for pipes, fittings, and valves made of carbon steel, stainless steel, and copper. Industrial alcohol is recommended for pipes, fittings, and valves made of aluminum alloy. Non metallic gaskets can only use industrial grade carbon tetrachloride. Defatting work should be carried out in a well ventilated area, and personnel should wear protective work clothes for operation. Do not sprinkle solvents on the ground to prevent the generation of vapors that may cause poisoning or fire. Smoking and open flames are strictly prohibited on the degreasing site. Although carbon tetrachloride cannot burn, it can decompose into toxic phosgene when exposed to fireworks, causing poisoning to the operator.

The method of removing oil from the inner surface of the pipe is to block one end of the pipe with a wooden plug, pour solvent into the other end, and then block it with a wooden plug. Place the pipe flat and let it sit for 10-15 minutes. At the same time, flip the pipe (3-4) times to wash the entire inner surface of the pipe with solvent, and then release the solvent (which can still be used). When using carbon tetrachloride or distilled alcohol as the solvent, after the solvent is released, it can be dried naturally or with clean compressed air without oil or moisture. If dichloroethane solvent is used, due to its high flammability and explosiveness, nitrogen should be used to blow dry the inner wall of the pipe until there is no solvent odor, and it should be left for more than 24 hours. After degreasing and drying, the ends of the tube should be blocked and wrapped with gauze to prevent further contamination.

The dosage of degreasing agent for pipes depends on the inner diameter and length of the pipe,

The outer surface of the pipe can be degreased by wiping it clean with a cloth soaked in solvent, and then placed in an open place to cool dry.

When it is necessary to perform inner wall degreasing due to contamination after the installation of the pipe, the installed pipe should be disassembled into separate sections without dead ends, and each of these separate sections should be filled with carbon tetrachloride for degreasing. Subsequently, clean and dry heated air is used for blowing, and the flow rate of the hot air is required to be no less than 15m/s. After blowing clean, assemble the pipe section. It is strictly prohibited to use other solvents for degreasing the installed pipes.

When degreasing valve components, they should be disassembled first, then immersed in a container containing solvent for 5-10 minutes, and then taken out for drying until there is no odor. The oil removal methods for metal gaskets, flanges, etc. are also the same.

The degreasing method for the filling material (asbestos packing) and asbestos gasket used during pipe installation is: first, place these filling materials and gaskets at a temperature of 300c for 2-3 minutes, and then apply graphite powder. Non metallic gaskets are only allowed to be degreased with carbon tetrachloride. First, place the gasket in a container containing a solvent and let it sit for 1-5 hours. Then, take it out and hang it separately with iron wire in a ventilated outdoor area for at least 24 hours. Forged copper gaskets, aluminum gaskets, etc. can no longer be degreased after annealing treatment.

After degreasing, the surface of the pipe fittings and padding can be wiped with white filter paper. If there are no oil stains on the paper, the degreasing is qualified. The degreased pipes and accessories should be properly stored to prevent further contamination by grease.

2、 Pipeline installation

The oxygen pipeline interface should be placed in a convenient location for inspection; Oxygen pipelines should be welded except for flange or threaded connections with equipment and accessories. When threaded connections are necessary, the filler used on the thread head should be a mixture of lead monoxide and water glass (sodium silicate) or distilled water, and polytetrafluoroethylene film should be used. Flaxseed lead oil should never be used. During pipeline welding, it is necessary to prevent splashing and slag particles from entering the pipe. After welding, all welds should be visually inspected, and non-destructive testing (X-ray and X-ray) should be performed on 100% of the total number of welds. Unqualified welds should be removed and re welded, and non-destructive testing should be conducted after the repair welding is completed.

3、 Pressure testing and blowing brush

After the installation of the oxygen pipeline is completed, a strength test and a tightness test should be conducted. The test media are oil-free water and air, respectively. The water pressure pump must also be degreased, and the air should be provided by a non lubricated air compressor.

The strength test uses water as the test medium and the test pressure is 1.25 times the working pressure. During the experiment, first increase the pressure to the test pressure and observe for 10 minutes. If the pressure does not decrease, then reduce it to the working pressure for visual inspection. If there is no rupture, deformation, or water leakage, the experiment is considered qualified.

The tightness test uses oil-free air or nitrogen as the test medium, and the test pressure is equal to the working pressure. During the experiment, first increase the pressure to the specified level, then apply soapy water to all interfaces for inspection, and observe for 24 hours. If there are no defects and the average hourly air leakage rate does not exceed 1%, it is considered qualified.

After passing the tightness test, the oxygen pipeline must be blown and brushed with air or nitrogen (neither containing oil), and the airflow velocity should not be less than 20m/s

Preparation for installation of GCE gas pressure reducer pipeline