In the process of boiler pipeline installation, several valves are needed, including gate valve, stop valve, check valve, pressure reducing valve, drain valve and safety valve. The function and significance of each valve are different. Today, let's talk about the function and installation mode of each valve.

1、 Gate valve

Also known as gate valve, is the use of gate to control the opening and closing of the valve, by changing the cross section to adjust the pipeline flow and opening and closing of the pipeline. Gate valves are mostly used for pipelines with full open or full close operation for fluid medium.

Gate valve installation generally has no directional requirements, but can not be inverted.

2、 Stop valve

Is the use of disc to control the opening and closing of the valve. By changing the clearance between the disc and the seat, that is, changing the size of the channel section to adjust the medium flow or cut off the medium channel. Pay attention to the flow direction when installing the stop valve.

The principle that must be observed when installing the stop valve is that the fluid in the pipeline passes through the valve hole from bottom to top, commonly known as "low in and high out", and reverse installation is not allowed.

3、 Check valve

Check valve, also known as check valve and one-way valve, is a kind of valve that opens and closes automatically under the pressure difference between the front and back of the valve. Its function is to make the medium flow in only one direction and prevent the medium from flowing backward.

Check valve according to its different structure, there are lift type, swing type and butterfly clamp type. Lift check valve is divided into horizontal and vertical.

When installing the check valve, also pay attention to the flow direction of the medium, can not be installed reversely.

4、 Pressure reducing valve

1. The pressure reducing valve group installed vertically is generally set at a suitable height from the ground along the wall; The pressure reducing valve group installed horizontally is generally installed on the permanent operation platform.

2. Profile steel shall be respectively loaded into the wall outside two control valves (commonly used for stop valve) to form a bracket, and the bypass pipe shall also be stuck on the bracket for leveling and alignment.

3. The pressure reducing valve shall be vertically installed on the horizontal pipeline, and shall not be inclined. The arrow on the valve body shall point to the medium flow direction, and shall not be installed reversely.

4. Stop valves and high and low pressure gauges should be installed on both sides to observe the pressure changes before and after the valve. The diameter of the pipe behind the pressure reducing valve shall be 2 # - 3 #, larger than that of the inlet in front of the valve, and the bypass pipe shall be installed for maintenance.

5. The equalizing pipe of membrane pressure reducing valve should be connected to the low pressure pipe. Safety valve shall be set for low pressure pipeline to ensure safe operation of the system.

6. When it is used for steam decompression, a drain pipe shall be set. For the pipeline system with high purification requirements, a filter should be set in front of the pressure reducing valve.

7. After the installation of pressure reducing valve group, the pressure reducing valve and safety valve shall be tested, washed and adjusted according to the design requirements, and the adjusted marks shall be made.

8. When flushing the pressure reducing valve, close the inlet valve of the pressure reducer and open the flushing valve for flushing.

5、 Steam trap

1. Block valve (stop valve) should be set before and after the steam trap, and a filter should be set between the steam trap and the front block valve to prevent the dirt in the condensate from blocking the steam trap.

2. A check pipe should be set between the drain valve and the rear block valve to check whether the drain valve works normally. If the check pipe is opened and a large amount of steam is emitted, the drain valve is broken and needs to be repaired.

3. The bypass pipe is set to discharge a large amount of condensate during start-up and reduce the drainage load of the steam trap.

4. When the steam trap is used to drain the condensate from the hot equipment, it should be installed at the lower part of the hot equipment, so that the condensate pipe can be connected to the steam trap vertically to prevent the hot equipment from storing water.

5. The installation position should be close to the drainage point as far as possible. If the distance is too far, air or steam will accumulate in the slender pipe in front of the trap.

6. When the horizontal pipeline of steam main is too long, the problem of drainage should be considered.

6、 Safety valve

1. Before installation, the product must be carefully inspected to check whether there is a certificate and product instructions, so as to clarify the constant pressure situation when leaving the factory.

2. The safety valve should be arranged near the platform as far as possible for inspection and maintenance.

3. The safety valve should be installed vertically, the medium should flow from the bottom to the top, and the verticality of the valve stem should be checked.

4. In general, the front and back of the safety valve can not be set with block valve to ensure safety and reliability.

5. Pressure relief of safety valve: when the medium is liquid, it is generally discharged into the pipeline or closed system; When the medium is gas, it is generally discharged to the outdoor atmosphere.

6. The oil and gas medium can be discharged into the atmosphere generally. The outlet of the relief pipe of the safety valve should be 3M higher than the highest structure around, but the following situations should be discharged into the closed system to ensure safety.

7. The minimum diameter of the pipeline shall be equal to the inlet diameter of the valve; The diameter of the discharge pipe shall not be less than the outlet diameter of the valve. The discharge pipe shall be led to the outside and installed with elbow, so that the outlet of the pipe faces the safety zone.

8. When the safety valve is installed, when the connection between the safety valve and equipment and pipeline is open hole welding, the opening diameter shall be the same as the nominal diameter of the safety valve.

The above boiler valves are installed in different places, and each has its own purpose. During the installation of boiler pipes, the operators should be careful and carry out the construction according to the drawings, with both quality and safety.