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Structural features of triple eccentric butterfly valve
发布时间：2018-10-25 来源：艾德威尔•瑞拓
Since its inception, the triple eccentric butterfly valves have undergone a process of self-improvement and continuous development in order to meet increasingly stringent working conditions. Even basic zero leakage, theoretically three eccentric butterfly valves can be achieved, but in fact depends on careful design and precision manufacturing. On the basis of absorbing and summarizing the lengths of other brands of three eccentric butterfly valves,
1, API specifications
As we all know, API609 has in fact become an international specification for valves used in industrially important pipelines. The three eccentric butterfly valves are designed and manufactured in strict accordance with the new 1997 edition of API609. What is more valuable is that the basic design of the three eccentric butterfly valves is not limited to the API specifications, BS5155ANSIB16.34, ASMESECVIII and other major specifications, which ensures that the three eccentric butterfly valves are used in all industrial fields.
2, balanced fixed structure
Starting from the shape characteristics of the sealing surface of the triple eccentric butterfly valve, the sealing method of the triple eccentric butterfly valve is fixed by the elliptical shape of the bolt, not only the positioning is accurate, but also the balance of each bolt is balanced, and the uneven distribution of stress is eliminated. The resulting seal pair is loose and leaks.
3. Double safety structure
The three eccentric butterfly valves are strictly in accordance with the specifications of API609, in order to prevent deformation of the disc caused by fluid pressure and temperature, misalignment of the valve stem, engagement of the sealing surface, and two independent thrusts on the lower side of the disc. Ring, thus ensuring the normal operation of the valve under any working condition;
At the same time, in order to prevent the sudden damage caused by the valve stem from being damaged or flying out due to unknown reasons, the independent valve stem flying out prevention mechanism is designed in the inner and outer parts of the lower end of the valve, which also ensures the three eccentric butterfly valve from the side. Pressure ratings can be as high as 2,500 pounds.
4, the body seat structure
There are two types of valve seat mounting structures for the three eccentric butterfly valves, most of which are mounted on the butterfly plate for convenience, but the three eccentric butterfly valves adopt the body valve seat structure and the valve seat is mounted on the body. The advantage is that compared with the butterfly seat, the chance of the valve seat directly contacting the medium is greatly reduced, thereby reducing the degree of erosion of the valve seat and prolonging the service life of the valve seat.
In the design process, the three eccentric butterfly valve specially considers the application problems in the regulation field, makes full use of the sealing principle of the triple eccentric butterfly valve, and realizes that the butterfly does not scrape the valve seat when the valve is switched, and the torque of the valve stem is directly transmitted through the butterfly plate. To the sealing surface, that is to say, there is almost no friction between the butterfly plate and the valve seat, thus eliminating the common jumping phenomenon of opening the ordinary valve, eradicating various unstable factors such as friction in the low opening range of the valve. The regulation can not be a phenomenon, that is, the dead zone is eliminated (not feeling), which means that the three eccentric butterfly valve can enter the controllable area from the 0 degree opening to 90 degrees, and its normal regulation ratio is more than twice that of the general butterfly valve. The regulation ratio can be as high as 100:1 or more. This creates good conditions for Tritec to be used as a regulating valve, especially at large diameters, where the cost of the shut-off valve is extremely high, and in addition, the shut-off valve cannot achieve zero leakage, in the case of emergency shut-off, at the shut-off valve The side valve is installed with a shut-off valve, and the three eccentric butterfly valves are controlled and shut down in one body, and the economic benefits are extremely considerable.
6, thin layer valve seat structure
The valve seat of the triple eccentric butterfly valve is formed by laminating stainless steel sheets and graphite sheets. This structure can effectively prevent the influence of minute solids in the medium and the sealing surface engagement caused by thermal expansion, even if slight damage occurs. Leakage occurs, which is unimaginable for double eccentric butterfly valves or other triple eccentric butterfly valves.
7. Essential refractory structure
Many valves claim to have a refractory construction, but most of them use a soft and hard double seat construction to reduce leakage, which is dangerous. Because the non-combustion of the soft-sealed valve seat in the fire causes stress and temperature difference deformation of the metal support valve seat, resulting in failure of the fire-resistant function. Therefore, at present, Europe and the United States are gradually eliminating such a nameless fire-resistant valve. Because the three-eccentric butterfly valve is zero-leakage, it does not require the help of a soft seal, a veritable essential refractory structure, and has a certificate of fire resistance inspection of API607, API6FA and BS6755Part2. This ensures that the three eccentric butterfly valves can be applied to various hazardous areas such as petroleum and petrochemical.
8, replaceable seal pair
The sealing pair of the triple eccentric butterfly valve can be described as unique, not only can the body seat be replaced, but also because the sealing surface of the butterfly plate is independent of the butterfly plate, and the sealing surface of the butterfly plate can also be replaced, that is, when the sealing surface of the butterfly plate is damaged, It is no longer necessary to move back to the manufacturing plant or to disassemble the valve, and only need to change the sealing surface of the butterfly plate, which not only greatly reduces the maintenance cost, but also greatly reduces the maintenance man-hour and maintenance intensity and difficulty.
