German STINIS valves STINIS models STINIS prices

The closing element of the STINIS valve is a plug-shaped disc, with a flat or conical sealing surface. The disc moves linearly along the centerline of the valve seat. The stem movement type (common name: rising stem) also includes lift-and-rotate stems. It can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, slurry, oil products, liquid metals, and radioactive media. Therefore, this type of shut-off stop valve is very suitable for isolation, regulation, and throttling. Because the opening or closing stroke of the valve stem of this type of valve is relatively short, and it has a very reliable shut-off function, and because the change in the valve seat port is directly proportional to the disc stroke, it is very suitable for flow regulation.

STINIS valve stop valve features

Compared with another commonly used shut-off valve in industrial production, the gate valve, the stop valve is simpler in structure, making it easier to manufacture and maintain. In terms of service life, the sealing surface of the stop valve is not easily worn or scratched. During the opening and closing process, there is no relative sliding between the disc and the seat sealing surface, resulting in less wear and damage to the sealing surface, thus extending the service life of the sealing pair. The disc stroke of the stop valve during full opening and closing is small, and its height is relatively smaller than that of the gate valve. The disadvantage of the stop valve is that the opening and closing torque is large and rapid opening and closing is difficult to achieve. Because the flow channel inside the valve body is quite tortuous, the fluid flow resistance is high, causing significant loss of fluid power in the pipeline.

Precautions for STINIS valve performance testing

1) When valves of a specific specification are manufactured in batches, an official agency should be commissioned to perform the following performance tests: (1) Opening and closing torque of the valve under working pressure conditions; (2) Detection of the flow resistance coefficient of the valve under pipeline water transmission conditions. 2) The following tests should be performed on the valve before leaving the factory: (1) With the valve in the open position, the valve body shall withstand an internal pressure test at twice the valve's working pressure; (2) With the valve in the closed position, both sides shall separately withstand 11 times the valve's working pressure without leakage; however, for butterfly valves with metal seals, the leakage value shall not exceed the relevant requirements.

STINIS valve operation

For stop valves, one must not only know how to install and maintain them, but also how to operate them. When opening or closing a stop valve, apply force steadily; do not use impact. Certain high-pressure stop valves designed for impact opening and closing have components that account for this impact force and cannot be equated with general stop valves. When the stop valve is fully open, turn the handwheel back slightly to tighten the threads and prevent loosening and damage. When the pipeline is first used, there may be a lot of dirt inside. You can slightly open the stop valve and use the high-speed flow of the medium to flush it away, then close it gently (do not close quickly or forcefully to prevent residual impurities from damaging the sealing surface), then open it again. Repeat this process several times to flush out the dirt before putting it into normal operation. For normally open stop valves, dirt may adhere to the sealing surface. When closing, use the above method to flush it clean, then close it tightly. If the handwheel or handle is damaged or lost, replace it immediately. Do not use an adjustable wrench as a substitute, to avoid damaging the square section of the valve stem, which could cause ineffective opening and closing and lead to accidents in production. For certain media, cooling after the stop valve is closed causes the valve parts to contract. The operator should close it again after an appropriate time to ensure no fine gaps remain on the sealing surface. Otherwise, the medium flowing through the fine gaps at high speed can easily erode the sealing surface. During operation, if the operation feels excessively strenuous, analyze the cause. If the packing is too tight, loosen it appropriately. If the valve stem is skewed, notify personnel for repair. Some stop valves experience difficulty in opening when the closing element expands due to heat in the closed state. If opening is necessary at this time, loosen the valve cover threads by half to one turn to relieve valve stem stress, then turn the handwheel.

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