Water-cooled High Temperature Forged Steel Valves

Water-cooled High Temperature Forged Steel Valves

Jan 06, 2021


1. Overview
A high temperature valve is one of the important and indispensable devices in the petrochemical industry, power station, long distance pipeline, nuclear industry, aerospace and high temperature engineering. With the rapid development of the industry and the development of export markets, the demand for high temperature valves and their requirements are getting higher and higher, and higher requirements are also put forward for the safety of high temperature valves. The structure of a water-cooled high temperature forged steel valve is introduced in this article.
 
2. Analysis of working conditions
(1) An extended valve bonnet is usually used for the high temperature forged valve to protect the packing. The extended bonnet adopts 3 connection methods such as the socket welding, threaded connection and butt welding.
When the connecting pipe and the valve bonnet are connected by socket welding or threaded connections, the outer diameter of the pipe should be increased in order to ensure the welding thickness, which increase the manufacturing cost. When the connecting pipe and the valve bonnet are connected by butt welding, the welding thickness remains unchanged, but the processing is complicated. In addition, the three connection methods have welding stress and seam quality problems, which brings hidden dangers to the safe operation of the valve.
(2) In the existing packing seal structure of the high temperature valve, the pre-tightening force applied to the packing by the eyelet bolt is constant. A slight decrease in the compression deformation of the packing caused by wear will increase the stress relaxation of the packing, thus reducing the stability and reliability of the sealing.
(3) After the packing is worn, the gap between the packing and the valve stem or the inner wall of the packing will become bigger. The packing seal structure of the high temperature valve does not have the ability to automatically compensate the pressing force. As the gap increases, the leakage will also increase.
 
3. Structure improvement
Considering the problem of valves used in high temperature conditions, a water-cooled high temperature forged steel valve was designed (Figure 1).
 

1. Valve bonnets 2. Cooling water tanks 3. Valve stems 4. Packing 5. Spring seats
6. Spring fixing rings 7. Springs 8. Eyelet bolts 9. Brackets
Figure 1 The water-cooled high temperature valve
 
Figure 2 Spring fixing rings

3.1 Technical parameters
Nominal diameters: from DN15 to DN50
Working pressure:14.0MPa
Working temperature: 900 ℃
Connection methods: butt welding and socket welding
Main parts: view table 1 for their materials.
 
Table 1 Materials of main parts
Names Materials
Valve bodies A105
Valve seats 1Crl3 + STL
Valve plates 1Crl3 + STL
Valve bonnets A105
Cooling water tanks 20
Spring fixing rings 2Cr13
Spring seats 2Cr13
Springs 304

3.2 Structural characteristics
(1) The extended valve bonnet adopts an integral forged structure. The valve bonnet and the bracket are connected by threads to avoid defects such as welding stress in the group-welded structure.
(2) A cooling water tank is provided on the extended valve bonnet. The cooling water tank adopts a half type, and the two halves of the cooling water tank are respectively inserted into the positioning groove of the extended valve bonnet and welded to ensure no leakage. The upper and lower cooling water tanks are respectively provided with cooling water inlets and outlets. The extended valve bonnet is cooled by the circulating cooling water in the cooling water tank, and the temperature difference between the inner and outer walls of the valve bonnet is controlled. The strength of the valve bonnet is improved, and the packing position is always maintained at a normal temperature.
(3) Place the spring in the uniformly distributed holes of the spring fixing ring (Figure 2). When the packing is worn, the spring pushes the spring seat to move and evenly distributes the elastic force on the packing for automatic compensation, so that the sealing end faces of the packing can always be kept in close contact automatically.
(4) Disc spring gaskets are used to compensate twice at the eyelet bolt connection to minimize the leakage rate.
 
4. Conclusion
The water-cooled high temperature valve has a significant cooling effect under the action of the cooling water tank, and the packing has certain compensation ability, excellent sealing performance and long service life. The water-cooled high temperature valve has been widely used in petroleum and chemical pipelines with stable performance and good effect.
 

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Launched in 1988, Topper Forged Valve Company is engaged in manufacturing forged steel valves. Our products cover Forged Steel Ball Valve, Gate Valve, Check Valve, Globe Valve, According to API, BS, DIN, JIS GB Standards.
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