• 14 taboos of installing a valve (Part Three)

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14 taboos of installing a valve (Part Three)

  • 08 13, 2018

Taboo 10

The flange plates and gaskets that joint pipelines are not strong enough, and the connecting bolts are short or have a small diameter. The rubber gasket is used for the heat pipe; the asbestos gasket is used for the cold water pipe; the double-layer gasket or the bevel gasket is used; and the flange gasket protrudes into the pipe.

Consequences: The flange connection is not tight or even damaged, and leakage occurs. The flange gasket protrudes into the pipe and increases the water flow resistance.

Measures: Pipe flange plates and gaskets must meet the pressure requirements for piping design.
Rubber asbestos gaskets should be used for the heating and hot water supply pipes; rubber gaskets should be used for the water supply and drainage pipes.

The gasket of the flange shall not protrude into the pipe, and the outer circle should just reach the flange bolt hole. Do not place a bevel gasket or several gaskets in the middle of the flange. The bolt diameter that connects the flange should be 2mm less than the inner diameter of the flange plate. The protruding length over nut of the bolt bar should be 1/2 of the thickness of the nut.

Taboo 11

The valve installation method is incorrect.

For example, the water or steam flow direction of the globe valve or check valve is opposite to the sign. The valve stem is installed downward. The horizontally mounted check valve is installed vertically. The required space isn't left for rising stem gate valve or the butterfly valve handle to open and close. The valve stem of the concealed valve isn't installed facing the inspection door.

Consequences: The valve is out of order. The switch is difficult to overhaul, and the valve stem is facing down, which often causes water leakage.

Measures: Strictly install valves according to the installation instructions. Enough space should be left for elongation of the valve stem of rising stem gate valves. The handle rotation space of butterfly valve should be fully considered. The various valve stems can't be lower than the horizontal position, and can't be installed downward. The concealed valve should be provided with an inspection door that meets the opening and closing requirements of the valve, and the stem should be installed facing the inspection door.
 
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