Do you know the major taboos of valve installation?

Valves are the most common equipment in chemical enterprises. It seems easy to install valves, but if they are not carried out according to the relevant technology, they will cause safety accidents.

1. Hydraulic test is carried out under negative temperature in winter construction.

Consequences: Because the pipe freezes quickly during the hydraulic test, the pipe is frozen out.

Measures: Water pressure test should be carried out as far as possible before winter operation, and water should be blown clean after pressure test, especially the water in the valve must be cleaned up, otherwise the valve will rust lightly and freeze crack heavily. It is necessary for the project to carry out hydraulic test in winter. It should be carried out at positive indoor temperature and the water should be blown clean after pressure test.

    2.Sewage, rainwater and condensate pipes are concealed without water closure test.

Consequences: It may cause leakage and user losses.

Measures: Closed water test should be checked and accepted strictly in accordance with the specifications. Underground burial, suspension roof, pipes and other hidden sewage, rainwater, condensate pipes, etc. to ensure that no leakage.

    3.The butterfly valve flange uses the ordinary valve flange.

Consequences: The size of butterfly valve flange is different from that of common valve flange. Some flanges have small inner diameter, while the disc of butterfly valve is large, which causes the valve to be damaged due to inability to open or rigid opening.

Measures: Processing flange according to actual size of butterfly valve flange

    4.Pipeline is directly buried in frozen soil and untreated loose soil. Pipeline pier spacing and location are inappropriate, even in the form of dry bricks.

Consequences: Pipeline is damaged during backfill compaction due to unstable support, resulting in rework repair.

Measures: Pipelines shall not be buried in frozen soil or untreated loose soil, the spacing of piers shall conform to the requirements of construction specifications, and the cushions shall be firm, especially at the pipeline interface, and shall not bear shear stress. Brick piers should be built with water and sediment slurry to ensure integrity and firmness.

    5.The valve installation method is wrong.

For example, the water (steam) flow direction of globe valve or check valve is opposite to the mark, the stem is installed downward, the check valve installed horizontally is installed vertically, the open stem gate valve or butterfly valve handle has no open or closed space, and the stem of the concealed valve does not face the check door.

Consequences: Valve failure, switch maintenance difficulties, valve stem downward often cause leakage.

Measures: Installation should be carried out strictly according to the installation instructions of the valve. Open stem gate valve keeps enough open height of the stem, butterfly valve fully considers the rotating space of the handle, and all kinds of valve rods should not be lower than the horizontal position, let alone down. Undercover valves should not only be equipped with check doors to meet the needs of valve opening and closing, but also the stem should be oriented towards the check door.

    6.Improper installation of valves in high temperature environment

Consequences: Leakage incidents

Measures: High temperature valves above 200 C are installed at normal temperature, but after normal use, the temperature rises, bolts expand and clearance increases, so they must be tightened again, which is called "hot tightening". Operators should pay attention to this work, otherwise leaks easily.