Selection of fuel gas pipeline materials

Generally, the medium and low pressure pipeline systems of gas, and natural gas can use cast iron pipe or polyethylene pipe and steel pipe, and high pressure systems must use steel pipe. Both liquid and gaseous LPG pipelines are made of steel tubes.

Indoor gas pipeline installation

1. Pipeline installation requirements

(1) When the gas pipeline is connected by thread, the gas pipe can choose thick white paint or PTFE film as the filler, and the gas pipe of natural gas or liquefied petroleum gas chooses petroleum sealing grease or PTFE film as the filler.

(2) The laying height of the gas pipeline (from the ground to the bottom of the pipeline or the insulation layer of the pipeline) shall meet the following requirements:

In places where people walk, the laying height should not be less than 2.2m;

The laying height should not be less than 4.5m where vehicles are passing.

2. Installation requirements of gas equipment

Fuel and gas pipes should be connected with hard pipe, galvanized live joint sealed with industrial grease sealing ring. The hose connection, the household kitchen burning gas burner and laboratory, the connecting hoses should not be more than 2 m in length, not due and interface, with the need of industrial production, moving the fuel gas combustion equipment, the length of the connecting hoses should not exceed 30 m, the interface should not exceed 2, the gas hose should be oil-resistant rubber hose, both ends with chuck and special connector, Hose should not run through walls, windows or doors. Gas pipelines shall be painted with yellow anticorrosion identification paint.

Outdoor gas pipeline installation

Basic requirements for pipeline installation

(1) The minimum thickness of buried underground gas pipeline shall meet the following requirements:

(2) When buried under the roadway, it shall not be less than 0.8m;

(3) It shall not be less than 0.6m when it is buried under non-roadway (or neighborhood);

(4) When buried in the courtyard, not less than 0.3m;

(5) When buried under paddy field, it shall not be less than 0.8m.

(6) When laying together with the pipeline conveying corrosive media, the gas pipeline should be mounted above. Protection measures should be taken on the gas pipeline for the parts that are easy to leak air, oil and corrosive liquid, such as flanges and valves.

(7) Release pipes (holes) should be set on both sides of the valve of medium pressure pipe of gas pipeline with diameter DN≥500mm and high pressure dry pipe of natural gas pipeline with diameter DN≥300mm; A release valve shall be set between the segments valves of the underground liquid LPG pipeline, and the distance between the outlet of the release pipe and the ground shall not be less than 2m. A pipeline safety valve shall be set on the pipe section between the two valves of the above-ground liquid LPG pipeline.

(8) Steel pipes used in gas pipelines (except galvanized steel pipes) should be treated with anti-corrosion before installation. The outer wall of overhead steel pipes should be coated with anti-rust paint such as epoxy iron red twice, and the outer wall of buried steel pipes should be anti-corrosion according to the design requirements. When the design has no rules, buried steel pipe anticorrosion epoxy coal asphalt can be used or polyethylene tape, buried galvanized steel tube outer wall and threaded parts should do regular grade anti-corrosion insulation, repair of the threaded connection is water asphalt coating and bind up three oil two glass fabric cloth processing, or use the epoxy coal asphalt coating and bandaging glass cloth for two oil a cloth processing.

(9) The connection of cast iron pipe shall adopt S-type mechanical interface, and the interface filler shall use gas rubber ring.

(10) The connection between cast iron pipe and steel pipe shall be made of flange. Malleable iron should be used for bolts. If steel bolts are used, anti-corrosion measures should be taken.

(11) Polyethylene gas pipelines shall be electrically fused (electrically fused socket connection, electrically fused saddle connection) or hot-fused (hot-fused socket connection, hot-fused butt connection, hot-fused saddle connection), and shall not be threaded connection and bonding. Steel - plastic transition joint is used when connecting with metal pipe. Cooling measures should be taken when welding steel pipe end of steel - plastic transition joint with steel pipe.

(12) Steel-plastic transition joints generally have two forms, for small-caliber polyethylene pipe (D≤63mm), generally adopt integrated steel-plastic transition joints; For large-diameter polyethylene pipes (D > 63mm), steel-plastic flange assembly is generally used for conversion connection.