Requirements for Assembly of Forged Steel Gate Valves

Forged steel gate valve seat shall have no gaps, there is no stress to increase the gap. After adjusting seat, does not allow the valve seat has rotation or rotation trend, do not allow that form the plastic deformation due to the expansion of the valve seat and the gate plate.

Need to use special expansion, assembled valve is used as as a positioning benchmark, expanding both ends. Forged steel gate valve body recover more than the amount of spring seat rebound, the valve body hole tightly surrounds the valve seat, does not have the gap, the seal is good. Therefore, it is necessary to strictly control the axial load. When the valve seat pressed to the valve body, the inner wall need be deformed within the elastic limit, to ensure that the expansion force disappears, the valve body wall rebound to make up the valve seat rebound, it is necessary to limit the maximum axial load.

Precautions for Maintenance of Forged Steel Gate Valve

Forged steel gate valve is suitable for small diameter pipe with working temperature -29 ~ 425 ℃ (carbon steel) or -29 ~ 500 ℃ (stainless steel), used to cut off or turn on the media in the pipeline. In daily use, the maintenance work is also particularly important, so the maintenance of forged steel gate valve is also a way to improve operating efficiency.
1. forged steel gate valve maintenance prevent the electric head and its transmission from the water, especially in the rainy season.
2. if the forged steel gate valve often switch, at least use lubrication once a month.
3. forged steel gate valve often overlook the problem of grease. After grease gun refueling, operators select the valve and grease injection mode, the grease injection operation.
4. regularly clean up forged steel gate valve to prevent debris to enter, affecting the normal operation of equipment.
5. the valve shaft parts have sliding sleeve or packing, also need to maintain lubrication status, to reduce the frictional resistance during operation. 

Fault Analysis of Stainless Steel Bellows Globe Valves

Stainless steel bellows valve installed in the pipeline of ship power plant, valve occurred stem leaks and stem rust and other issues. After fault analysis, taken appropriate solutions to eliminate the failure to ensure the performance of the valve. Binding site usage analysis, stem leakage mainly due to the valve main structure, the working environment and use operation. 

Bellows globe valve harsh working environment is one of the reasons of causing the failure. Since the bellows valve mounted on the hull in the salt spray environment, and often the upper part of condensate dripping, resulting in an upper thrust ball bearing corrosion, cause the stem contact corrosion.

In use, if open or closed bellows globe valve excessively, it may cause the valve can not meet the performance requirements. When we close the valve, it is possible to crush the sealing surface, cause seal failure, when the valve is opened excessively, resulting in valve leakage.

Quality of Forged Steel Gate Valve

Quality of forged steel gate valve depends on the quality of the sealing portion, its seat assembly is one of the key projects in the manufacturing process.
press-fit the seat usually used press-fitting process for the assembly, but for the seat with the wedge surface, its circumference is difficult to accurately control the position, the inner sealing surface may have deformation. For larger-diameter valve, the circumferential assembly error is larger, seriously affect the quality of the product. It adopted and the body gap with the surface of the wedge seat, get matched shutter to find positive position, then brakes tight, after the expansion of the whole assembly at both ends, so that deformation of the rear is less. All modifications must comply with stringent process parameters.

Valve Installation Requirements

Valve should be located in easily accessible, easy to operate, repair place. Valve on rows piping arrangement should focus on platforms and ladders, the valve on the pipeline should be arranged parallel, the center line should be neat. Accident valve such as fire and water valves, fire steam valves should be decentralized arrangement, consider the safe operation of the accident. Such valves to be arranged in the control room, behind security wall or outside the plant, to ensure that the operator is safe to operate.
Lift check valve should be installed in horizontal pipelines, vertical lift check valve can be mounted in a vertical pipe tube, swing check valve priority should be installed on a horizontal pipe, it can also be installed in the tube. Valves around operating platform handwheel platform edge from the center of not more than 450mm, when the valve stem and hand wheel extends into the top of the platform and a height of less than 2 meters, it should not affect the operation and traffic operator.

Improvement Experiments about Globe Valve on The Sealing Material

Practice shows that valves seal often only a few times for the opening and closing, because sealing abrasion caused by the leak. Minor scratches need open and repair, abrasions serious were scrapped damage, such consequences will not only increase the company's manufacturing costs, but also affect the performance of the globe valve. In order to solve such problems of the valve sealing material has been improved.
Change on the sealing material. Cone on the stem seal surfacing alloy good anti-abrasion performance, this method has yielded good results, but on the one hand because the good alloy cost is too high, on the other hand, since the stem base material for the 13Cr martensitic stainless steel, weldability is poor, required to preheat before welding, after welding, insulation and welding complex air compressor valve, spring safety valve, inching valve spring. In addition, in order to ensure the dimensional accuracy of the stem, but also increase the roughing process. Comprehensive analysis, in addition to special requirements, the cost of this program is not good.