Category: Industrial valves knowledge

Leakage of valve body and bonnet:

Reason:

1. The casting quality of iron castings is not high, and there are defects such as blisters, loose tissues, slag inclusions on the valve body and bonnet body

2. Freeze cracking;

3. Poor welding, there are defects such as slag inclusion, non-welding, stress cracks, etc.;

4. The cast iron valve is damaged after being hit by a heavy object.

In the flow control system, valve is a device used to control the direction, pressure, and flow of the fluid. During the construction process, the quality of valve installation directly affects the normal operation in the future, so the construction unit and production unit must pay great attention to it.

Now let we talk about technical requirements for valve installation

Section 1 Maintenance of the valve during transportation 

The valve hand wheel is damaged, the valve stem is bent, the bracket is broken, and the flange sealing surface is bumped and damaged, especially the damage of the gray cast iron valve. A considerable part of it occurs in the valve transportation process. The reason for the above-mentioned damage is mainly caused by the poor understanding of the basic common sense of the valve by the transportation personnel and the brutal loading and unloading operations.

Manual valve is a kind of valve commonly used in equipment and devices, it is operated by handle and hand wheel. In general, clockwise rotation of the handle and handwheel is defined as the closing direction, and counterclockwise rotation is defined as the opening direction. However, the opening and closing direction of some valves is opposite to the above, so please pay attention to check the opening and closing signs before operating

Valve working pressure is required to be greater than or equal to the working pressure of the pipeline. Under the premise of not affecting the price, the working pressure that the valve can withstand should be greater than the actual working pressure of the pipeline; any side of the valve should be able to withstand 1.1 times the working pressure of the valve when the valve is closed Value without leakage; when the valve is open, the valve body should be able to withstand 1.5 times the valve working pressure.

With the rapid development of technology and innovation, valuable information that should be delivered to industry professionals is often covered up today. Although shortcuts or quick methods can well reflect short-term budgets, they show a lack of experience and overall understanding of what makes the system viable in the long run. Based on these experiences, the following (without special importance) lists 10 common installation mistakes that are easy to overlook:

1 Applicable safety regulations must be complied with.
2 Ensure that the pipeline is free of impurities before the valve is installed, otherwise it will cause damage to the valve.
3 Connect the valve and pay attention to aligning with the pipeline.
4 For all valves, the actuator must be disassembled before welding on the valve body.

Features and selection of diaphragm valve
(1) The fluid resistance is small.
(2) It can be used for the medium containing hard suspended solids; since the medium only contacts the valve body and the diaphragm, there is no need for stuffing box, there is no stuffing box leakage problem, and there is no possibility of corrosion to the valve stem.
(3) Suitable for corrosive, viscous, and slurry media.
(4) Cannot be used in high pressure occasions.

Diaphragm valve is a special form of shut-off valve. Compared with other valves, it has the following characteristics:

1.The elastic sealing opening and closing parts ensure that there is no internal leakage;

2.Streamlined flow channel makes pressure loss limited;

3. There is no packing, so there is no leakage;