The most reasonable transmission of both water and gas is by pipeline. In water supply projects, modern water treatment plants, after taking water from the water source, through sedimentation, filtration into the clear water pool, and then pumped to the urban network, directly to the user. The pressure of the trunk pipeline is high (1.6-2.4MPa), and the pressure of the urban pipeline network is generally 0.5-1.0MPa to ensure that the residents can use water normally. With the improvement of people’s quality of life, the water supply pipelines in residential areas can be divided into drinking water pipelines, general water pipelines, hot water pipelines, etc. Gas engineering, according to the use is divided into urban pipeline network, courtyard pipeline network, indoor pipeline. According to the pressure is divided into high-pressure pipeline (0.3 < P ≤ 0.8 . P – pressure, unit MPa), secondary high-pressure pipeline (0.15 < P ≤ 0.3), medium-pressure pipeline (0.005 < P ≤ 0.15), low-pressure pipeline (P ≤ 0.005).
All kinds of pipelines have their own specific functions and strict requirements for each of them. The general requirements of the city pipeline are: not to endanger the safety, as far as possible, stable concealed laying, good anti-corrosion performance, long service life, investment savings, easy operation and maintenance. For the water supply pipeline, it is also required not to pollute water quality and not to breed bacteria. Special requirements for gas pipelines are to have sufficient strength, no leakage, etc.
In response to the above, the alloy steel pipe factory gives recommendations.
Water supply projects, gas projects related to thousands of households, to provide users with safe and reliable pipeline gas, supply people with clean and sanitary tap water, is the responsibility of decision makers and professional designers. Engineering decision-making, design process of steel pipe selection, should be a smaller input to obtain greater satisfaction. The Center, based on in-depth theoretical research and long-term practical experience, the following recommendations for the leadership and expert reference.
Water supply engineering.
(1) urban water supply trunk pipeline (DN500-DN800), it is appropriate to use spiral submerged arc welded steel pipe, the inner wall with non-toxic epoxy powder coating, the outer wall with three layers of PE anti-corrosion or epoxy powder corrosion.
(2) urban water supply branch line (DN300-DN500) should use spiral submerged arc welded steel pipe, the inner and outer wall with epoxy powder anti-corrosion.
(3) courtyard pipe network (DN100-DN300), it is appropriate to use ERW steel pipe or spiral submerged arc welded steel pipe, the inner and outer walls are coated with epoxy powder anti-corrosion.
(4) Intake riser (DN20-DN50), steel-plastic composite pipe, steel pipe base, inside and outside wall galvanized, inside and outside wall epoxy powder coating anti-corrosion.
(5) indoor pipeline (DN15-DN20), it is appropriate to use aluminum-plastic composite pipe, PPR plastic pipe, etc., beautiful appearance, convenient installation, moderate price.
(1) buried gas transmission trunk line, can choose spiral submerged arc welding steel pipe, steel pipe material should be in line with the provisions of GB50251, the inner wall does not need anti-corrosion, the outer wall available three-layer PE, epoxy powder, coal tar enamel coating corrosion.
(2) high – medium pressure pipeline, it is appropriate to use ERW steel pipe as the base of the epoxy powder coated steel pipe, the inner wall does not need anti-corrosion, welding connection, liquid epoxy coating patch.
3） For courtyard pipe network, steel-plastic composite pipe, steel pipe base, epoxy powder coated anti-corrosion outer wall, no anti-corrosion inner wall, welded connection, liquid epoxy coating patch.
(4) Into the house riser, it is appropriate to use steel-plastic composite pipe, steel pipe matrix, external wall galvanized, internal wall epoxy powder anti-corrosion.
(5) indoor pipeline, it is appropriate to use aluminum-plastic composite pipe for open installation, and steel-plastic composite pipe with steel pipe base, outer wall galvanized and inner wall epoxy powder anti-corrosion for concealed installation.