Attention to those involved in installation work: several common issues

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In pipeline construction, it is necessary to provide clear instructions first and carry out the work in accordance with the drawings； The establishment of material databases and welding databases provides strong guidance for construction ； Before pressure testing, it is necessary to understand the process and divide the area to be tested; different pressures require separate testing procedures. The brackets must be properly manufactured and installed, and various inspections must be carried out, including RT, PT, MT, UT, as well as PMI, heat treatment, and hardness testing ； The welding records prior to pressure testing should include the above contents. In pipeline construction, consideration must also be given to the intersections with other specialties.

It’s very useful; we’re about to start the installation!

I’m sorry for the delay of a few days; below are my own answers. 1. What issues should be considered in pipeline installation? Answer: Understanding and mastery of pipeline process drawings and construction technical documents; specifications, materials, and quality of pipes and their welding materials; whether the pipes require treatment (such as sandblasting for rust removal, pickling and passivation, heat treatment, etc.); the technical skills of plumbers and welders (such as certification, use of tools and equipment, work experience, and sense of responsibility, etc.); safety protection measures (such as welder goggles, grinding goggles, safety helmets, and safety belts for working at heights, etc.); whether the specifications, materials, and pressure ratings of valves, their bolts, gaskets, and flanges match the requirements of the pipes; and the fabrication and installation of auxiliary components such as pipe supports and hangers. 2. Factors affecting pipeline installation. Answer: Misunderstanding of the drawings, incorrect use or substandard quality of welding rods and wires, inadequate pre-treatment, the quality of welding by the welder, improper sequence of prefabrication and installation by pipe fitters, the quality of grinding and butting of weld joints, and so on. 3. What issues should be checked before pipeline pressure testing? Answer: The items to be checked before pipeline pressure testing are: (1) Whether the pressure testing plan and the pressure testing sketch (pressure testing package) have been properly prepared ； ⑵Whether the pipes and their components have been installed, whether the process flow is correct, whether the welds are clearly visible without any obstructions, whether the pipe supports and hangers are properly installed, and whether the labeling on the pipes and welds is complete and accurate ； ⑶Has the bolt washer for the temporary pressure testing blind flange been installed in that area? ； ⑷Whether the valve is installed correctly (such as whether the material, model, and pressure rating of the valve, its bolts, gaskets, and flanges are accurate) ； ⑸Valves, safety valves, burst discs, and instrument components have been removed or isolated; ⑹ Whether warning lines have been set up around the pressure testing area and whether unauthorized personnel have been evacuated; ⑺ Whether the air source (the water source for hydraulic testing) is ready, and whether the tools and equipment (such as pressure gauges, safety belts, binoculars, walkie-talkies, leak detection tools, compressors, etc.) are in good working condition; ⑻ Inspection of the measures taken for venting and draining. ⑼The technical documents are thoroughly prepared (various treatment reports, non-destructive testing reports, quality certification reports, welding records, welder registration records, records of concealed works, and so on). 4. Which issues must be resolved before pressure testing, and which can be dealt with after it? Answer: (1) Tasks that must be completed before pressure testing include welding, non-destructive testing, installation of supports, installation of valve bolts, gaskets, and flanges, as well as the organization of various documents and technical records. ⑵Activities that can be carried out after pressure testing include anti-corrosion and insulation work, the installation and calibration of electrical instruments, and the installation of safety valves, among others. 5. What are the two parameters for adjusting a safety valve? Answer: The setting pressure and return pressure of the safety valve. 6. Which components can participate in pipeline pressure testing, and which cannot? Answer: Instruments, control valves, flow orifice plates, flow restriction orifice plates, flow meters, steam traps, safety valves, etc., cannot be used in pressure testing; other components can be used for such testing. 7. What components does a control valve assembly consist of? Answer: The control valve assembly consists of: globe valves, flow control valves, and other components. 8. What issues should be considered when testing steam pipes? Precautions to be taken before pressure testing steam pipes: (1) Check whether the sliding pipe supports on the pipes can slide freely along the axial direction ； ⑵Is the fixed pipe support securely fastened? ； ⑶Is the position of the guide tube support correct? ； ⑷Are the high-discharge low-discharge valves properly installed and in good condition? ； ⑸Visual inspection and non-destructive testing of the pipeline have been completed ； ⑹Has the pressure gauge passed the calibration? Is a source of water for testing available? Is there a plan for waste water disposal? ； ⑺The personnel involved in the pressure testing are aware of the plan and their responsibilities, and safety measures have been put in place ； ⑻The areas affected by the pressure testing have been protected with cut-offs. 9. What is the typical pressure testing time for steam pipelines? Answer: Generally, for steam pipelines, the pressure is first increased slowly to the test pressure, then held at that level for 10 minutes. After that, the pressure is reduced to the operating pressure; if there is no drop in pressure or leaks after 30 minutes, it is considered successful. 10. What is the experimental pressure in water for the pipeline? Air pressure? In what situations is third-party approval required for pneumatic pressure testing? Answer: (1) The pressure for hydraulic testing is as follows: a. For steel pipes and non-ferrous metal pipes subjected to internal pressure, the testing pressure should be 1.5 times the design pressure; for buried steel pipes, it should also be 1.5 times the design pressure, with a minimum of 0.4 Mpa. b. For buried cast iron pipes under internal pressure, if the design pressure is less than or equal to 0.5 Mpa, the testing pressure should be 2 times the design pressure; if the design pressure is greater than or equal to 0.5 Mpa, it should be the design pressure plus 0.5 Mpa. c. For pipes subjected to external pressure, the testing pressure should be 1.5 times the difference between the design internal and external pressures, with a minimum of 0.2 Mpa. (2) The pressure for pneumatic testing is as follows: a. For steel pipes and non-ferrous metal pipes under internal pressure, the testing pressure should be 1.15 times the design pressure; for vacuum pipes, the testing pressure should be 0.2 Mpa. When the design pressure of the pipe is greater than 0.6 Mpa, approval from the general contractor, the supervising unit, and the project owner is necessary before carrying out the pressure testing.

These are all the most basic things; even exams should cover them