Jul 24,2014

All kinds of commonly used valve technical specification

The valve refer to the following standards:

GB12234 gate design standard

GB12235 cut-off valve design standards

GB12236 check valve design standards

GB12237 ball valve design standards

GB12238 butterfly valve design standards

JB/T7748 valve cleanliness and measuring method

JB/T7928 general valve supply requirements

JB/T7911 convex integral cast steel flange

JB/T1751 valve structural elements, socket connection and with the pipe size

JB / 308-75 valve model establishment method

GB/T13927 valve pressure test

GB12221 flange connection structure of metal valve length

GB12220 general valve

ZBJ16 006 test and inspection of the valve

ZBJ98 015 boiler pressure steel pipe accessories technical conditions

A, gate valve,

Gate is one of the most commonly used block valve is mainly used to connect or truncation pipeline medium, does not apply to adjust the medium flow. Gate valve for pressure, temperature and diameter range is very large, especially suitable for medium and large diameter pipeline.

1, the main advantage of the gate

(1) the fluid resistance is small. Gate valve gate body internal media channel is direct, medium flows through the gate without change the direction of activity, thus activities less resistance.

(2) the opening and closing more effort. Open/close the gate vertical movement direction and the direction of media activities. Compared with the cut-off valve, gate valve opening and closing more effort.

(3) medium activity direction is generally not restricted. Medium flow from the gate on both sides of any direction, can achieve the goal of connected or truncate. Easy to install, suitable for medium activity may change in the direction of pipeline.

2, the main drawback of gate valves

(1) large height, opening and closing time. Because when opening the gate must be complete ascension into the upper seat channel again when closed the gate must be all drop blocking seat channel, so the gate opening and closing of the trip is very large, its height also increases accordingly, open/close for a long time. (2) the sealing surface are prone to scratch. Open/close the gate between the two in contact with the valve seat sealing surface relative sliding under the action of a force of medium susceptible to scratches, and the sealing performance, affect the service life.

3, the structure of gate valve

Gate valves according to the structure and movement mode is divided into the stem rising stem gate valves and non-rising stem gate valves. Rising stem gate valves with the stem drive disc lift, valve stem drive screw thread on the outside of the body, therefore, according to the movement direction of the valve stem and directly determine the gate opening and closing and location, and thread for lubrication and transmission fluid corrosion, but it requires a larger installation space. Non-rising stem gate drive screw is located inside the body, in the process of opening and closing, the valve stem rotation of the only, disc in the valve body. Therefore, the height of the valve size. Non-rising stem valve gate, usually installed above the valve cover open-close position indicator, to apply to vessels, pipe trench less space and dust content such as the big environment.

Gate valves can also be according to the different structures of the gate is divided into two categories, wedge type and parallel type.

Can be divided into the rigid wedge gate single ram, elastic single ram and double ram, etc.

Rigid single wedge gate has simple structure, small size, use more reliable. But the wedge Angle of processing, with high accuracy, easy clamping and bruises occur, it is interesting, in the temperature of the medium and pressure of the gate. Wedge elastic single ram can be generated by ram traces of elastic deformation of the compensation function to achieve good sealing, temperature change is not easy to cause death of wedge, wedge Angle precision is low. But should prevent excessive torque closed and make the gate to the elastic. It is suitable for all kinds of temperature and pressure of gate valves.

Double wedge type gate wedge to the sealing surface of machining accuracy is low, easy to seal, the temperature change is not easy to cause jam and abrasions, convenient maintenance after sealing surface wear. But the structure is more complex, parts, valve size and weight is bigger.

Parallel type single ram structure is simple, not on its own to achieve forced sealing, in order to ensure its tightness, generally USES the soft sealing of fixed or floating, suitable for medium and low pressure, large, medium, and medium for oil or gas and natural gas, etc.

Parallel-type double ram generally produces sealing force through the upper beam, relative movement between the sealing surface is small, not easy scratches, more than gate valves for low pressure, medium and small size.

4, gate the main criteria

(1) GB12232-1989 "the common valve flange connection iron gate"

(2) GB12234-1989 "general valve flange and butt welding steel gate"

(3) GB8464-1987 "internal thread connecting gate valve, globe valve, ball valve, check valve, general technical conditions"

(4) GB8465.1-1987 "internal thread connecting gate valve, globe valve, ball valve, check valve basic size iron gate"

(5) the JB/T53162-1994 "gate valve product quality grading"

(6) JB/T5298-1991 "pipeline with steel plate gate valve,

5, valve installation and maintenance

(1) double disc gate valves should be erected installation, the valve stem in a vertical position, the handwheel at the top. Manual single disc gate valves can be installed in any position.

Gate valve (2) the belt transmission mechanism (such as gear drive, electric, pneumatic or hydraulic, etc.), shall be in accordance with the regulations of the product instruction manual installation.

(3) the handwheel, transmission mechanism are not allowed to use lifting use, and it is forbidden to collision.

(4) with bypass valve gate valve, can balance the import and export of differential pressure and reduce the opening force, so before the opening, should first open the bypass valve.

Second, the cut-off valve

Globe valve is a kind of common block valves, is mainly used to connect or truncation pipeline medium, is generally not used to adjust flow. Globe valve for pressure, temperature range is very big, but is generally used in medium and small diameter pipeline.

(1) the main advantage of the cut-off valve

1) compared with gate valve, globe valve structure is relatively simple, manufacture and maintenance are convenient.

2) the sealing surface is not easy to wear, abrasion, good sealing, long service life.

3) disc stroke is small when opening and closing, opening and closing time is shorter, smaller valve height.

(2) the main drawback of globe valve

1) fluid resistance. Body medium channel is more twists and turns, so the energy consumption is bigger. But the once-through cut-off valve fluid resistance is relatively small.

2) the open-close torque, opening and closing the effort. When closed, because the disc movement direction generally in the opposite direction to the medium pressure, must overcome the forces of the medium, so the open-close torque. And high pressure large diameter valve can be used in balance type structure, to reduce the opening and closing torque.

3) the direction of medium activity restricted. General requirements of medium from the bottom up.

(3) the structure of globe valve As the structure of the valve body has a straight-through, straight and right Angle type. Straight-through are the most common type of structure, but the fluid resistance is the largest. Straight flow of the fluid resistance small, usually for containing solids or the viscosity of fluid. Right Angle type body use casting, more suitable for small size, high pressure cut-off valve.

(4) the main standard globe valve

1) GB12233-1989 "general iron globe valve valve and lift check valve"

2) GB12235-1989 "general valve flange connection steel globe valve and lift check valve"

(5) cut-off valve installation and maintenance

1) hand wheel, lever manipulation of stop valve can be installed in any position.

2) hand wheel, lever and the transmission mechanism do not allow for lifting.

3) when installation should pay attention to make the flow of medium and the body referred to in the same direction of the arrow.

4) the belt transmission mechanism of cut-off valve (e.g., gear drive, electric, pneumatic or hydraulic), shall be in accordance with the regulations of the product instruction manual installation.

Third, the check valve

Check valves are automatically prevent fluid backflow valve. Check valve open valve under the effect of fluid pressure, fluid flow from inlet side to export side. When the import side pressure is lower than the export side, the disc in the fluid pressure difference, itself under the action of gravity factors such as automatic closed to prevent fluid backflow.

Check valves are generally divided into lift, swing, butterfly and several types such as diaphragm type.

Lift check valve general similar to cut-off valve, the structure of the disc along the center line of the channel for lifting movement, reliable action, but the fluid resistance is bigger, is suitable for the occasion of a small diameter. Lift check valve can be divided into straight-through and vertical two kinds. Straight-through lift check valve generally can only be installed in a horizontal pipe, and the vertical lift check valve should be installed in a vertical pipe commonly.

Swing check valve disc around the axis of rotation. The fluid resistance is generally less than lift check valve, it is suitable for large caliber of occasions. Swing check valve according to the number of the disc can be divided into single swing, more than double disc swing and swing three segments. Single swing check valves are generally applicable to medium caliber. Large diameter single swing check valve is used in the pipeline, to reduce the water hammer pressure, had better use can reduce the water hammer pressure slowly-closing check valve. Double disc swing check valve applicable Yu Dazhong diameter pipeline. Double disc swing check valve to the clamp structure is small, light weight, is a kind of check valve fast development; More disc swing check valve is suitable for large diameter pipe road.

The structure of the butterfly check valve is similar to the butterfly valve. Its simple structure, small flow resistance, water hammer pressure is small.

Diaphragm type check valve has a variety of structural form, adopt the diaphragm as open-close part, hammer due to its waterproof performance is good, simple structure and low capital, has developed rapidly in recent years. But the use of diaphragm type check valve temperature and pressure is limited by a diaphragm material.

Check the main criteria:

(1) GB12233-1989 "general iron globe valves and valve lift check valve"

(2) GB12235-1989 "general valve flange connection steel globe valve and lift check valve"

(3) GB12236-1989 "general valve steel swing check valves,

(4) GB/T13932-1992 "general iron swing check valves, valve

Check the installation and use

Straight-through lift check valve should be installed in horizontal pipe road, the bottom of the vertical lift check valve and valve is generally installed in a vertical tube road, bottom-up activities and media.

Swing check valve installation position is not restricted, are normally installed in horizontal pipe, but also can be installed in vertical or inclined tube road.

Install the check valve, should pay special attention to the medium activity direction, should make the normal activity of medium direction consistent with the direction of the arrow on the valve body, otherwise it will be truncated normal activities of the medium. Bottom valve should be installed at the bottom of the pump suction pipe.

Check valve is closed, middle water hammer in pipeline pressure, will cause serious damage to valves and piping or equipment, especially for large diameter pipeline or high pressure pipeline, reason should be the height of the causes of the check valve selection.

Four, ball valve

Ball ball valve is used with circular hole as opening and closing parts, ball with stem movement, in order to realize the on-off movement.ball valve.

1, the advantages of ball valve

(1) the fluid resistance is small. Full open channel, the body of ball and the connection of the pipe is equal to the cross-sectional area, and in a straight line are interlinked, medium flows through the ball valve, equivalent to flow through a straight pipe, in each kind of valve ball valve fluid resistance is minimal.

(2) the opening and closing fast. Only when the opening and closing the ball rotate 90 °, convenient and fast.

(3) the structure is simple, smaller volume, lighter in weight. In particular, it is far less than the height of gate and globe valves.

(4) the sealing performance is better. Ball valve generally adopt flexible soft sealing ring.

2, the shortcomings of ball valve

Use small temperature range. Ball valve generally adopt soft sealing ring, using temperature restricted by sealing ring material.