I. Gas Pipeline Laying
1. Gas pipelines should be equipped with anti-static and lightning grounding devices. The grounding resistance should not exceed 10Ω, and the flange connection resistance should be less than 0.03Ω. Testing should be conducted every six months. Grounding devices should be installed at the ends and bends of the pipeline. The distance between adjacent grounding devices on straight sections should be ≤ 100m, but pipelines within 25m of buildings must be grounded once. Lightning protection facilities must comply with GB 50057.
2. Heat insulation measures should be taken when overhead pipelines are laid near high-temperature heat sources or when vehicles carrying glowing objects frequently pass under the pipelines.
3. In cold regions where pipeline blockage due to freezing may occur, anti-freezing measures must be implemented.
4. No buildings unrelated to gas pipelines should be arranged under laid gas pipelines. Gas pipelines must not be laid in storage yards or warehouses for flammable and explosive materials, and must avoid production, storage, and loading facilities with strong corrosivity. They must not pass through unrelated buildings, production units, or tank areas.
5. Power cables and wires must not be laid on gas pipelines and supports, except for those used by the gas pipelines themselves.
6. Reliable isolation devices must be installed at the connection of branch pipes on the main gas distribution pipe and at the entrance of user pipelines.
7. For workshop cold gas pipes equipped with isolation devices, flow sensing elements, pressure gauge joints, sampling nozzles, and vent pipes, the operating positions should be located on platforms near the outside of the workshop.
8. Obvious signs must be placed on the ground for drainage devices, valves, and bends of underground pipelines.
9. For replaced or repaired gas pipelines, the length of the blind end should not be less than 0.5m. Airtightness and strength tests must comply with GB 6222.
10. Overhead gas pipelines crossing the main roads of the plant area must have height limit signs. For pipelines lower than 5m, crash barriers must be installed at least 10 meters away from both sides of the pipeline.
11. Warning signs such as “Gas Area, No Smoking or Fire” and “Prevent Poisoning” must be hung in all places where gas leakage may occur.
II. Corrosion Protection and Coating
1. Corrosion protection of gas pipelines should be determined based on the characteristics of the gas medium and the surrounding atmospheric environment, including the type of paint, number of coats, and dry film thickness. Painting must comply with GB 50726.
2. After the gas pipeline is fabricated, anti-rust coatings should be applied to the inner and outer surfaces. After installation and successful testing, all outer surfaces of the pipeline should be recoated with anti-rust paint. The outer surface of the pipeline should be repainted every 4 to 5 years, while in coastal areas, it can be repainted every 1 to 2 years depending on the corrosion condition.
3. The coating structure of gas pipelines should not adopt a single variety as the protective layer. Surface treatment and painting of on-site butt welds of gas pipelines should be carried out after the gas tightness test is qualified.
4. The color and identification of gas pipelines must comply with GB 7231. The gas type identification should be marked with Chinese characters such as “焦炉煤气 (Coke Oven Gas)”, “高炉煤气 (Blast Furnace Gas)”, and “转炉煤气 (Converter Gas)”, with a font size and position clearly visible from the ground. The gas flow direction is indicated by arrows. Identification should be set on pipelines at start points, end points, intersection points, bends, valves, both sides of wall penetrations, and other necessary locations.
5. For blast furnace gas pipelines using blast furnace raw materials rich in acidic ions, the inner wall should be coated with anti-corrosion paint. The pH value of condensate in the gas pipeline network should be tested regularly. If it is acidic, spray neutralization facilities should be set up to reduce acidic ions in the gas.
