What is a Ball Valve?

Ball valve (ball valve), a valve that is driven by a valve stem and rotates around the axis of the ball valve. It can also be used for the regulation and control of fluids. The hard-sealed V-ball valve has a strong shear force between the V-shaped core and the metal valve seat of the hard alloy, which is especially suitable for fibers and small solid particles And other media. The multi-way ball valve can not only flexibly control the confluence, divergence, and flow direction of the medium on the pipeline, but also can close any channel and connect the other two channels. This type of valve should generally be installed horizontally in the pipeline. Ball valve is divided into pneumatic ball valve, electric ball valve and manual ball valve according to the driving mode.

Ball valves were introduced in the 1950s.

First, wear resistance; Because the valve core of the hard seal ball valve is alloy steel spray welding,

1. The three-way ball valve adopts an integrated structure in structure, a sealed type of four-sided valve seat, less flange connection, high reliability, and lightweight design.

2. Tee ball core is divided into T type and L type, with long service life, large flow capacity and low resistance.

3. The ball valve is divided into single-acting and double-acting types according to the action type. The single-acting type is characterized in that the ball valve will be in the state required by the control system if the power source fails.

Advantages :

1. Nominal pressure or pressure level: PN1.0-32.0MPa, ANSI CLASS 150-900, JIS10-20K;

2. Nominal diameter or caliber: DN6 900, NPS 1/4 36;

3. Connection method: flange, butt welding, thread, socket welding, etc.

4. Applicable temperature: -196 540 ;

5. Driving mode: manual, worm and worm drive, pneumatic, electric, hydraulic, gas-hydraulic linkage, electro-hydraulic linkage;

6. Valve body material: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8 (304), CF3 (304L), CF8M (316), CF3M (316L), Ti. Different materials are used, which can be suitable for various media such as water, steam, oil, nitric acid, acetic acid, oxidizing media, urea, etc.

The nameplate shows the maximum operating pressure allowed for the ball valve at the maximum and minimum operating temperatures.

Use PTFE or RTFE valve seats and seals. The operating temperature of other types of valve seats and seals should be checked by the KI factory.

The nominal pressure level (PN) of the valve can indicate the maximum working pressure of the valve under normal temperature conditions. (For example: PN4.0, indicating that the maximum working pressure is -40 Bar (4.0 MPa) when the operating temperature is -190C to 380C).

Electric or pneumatic

Having a long service life and maintenance-free period will depend on several factors: normal working conditions, maintaining a harmonious temperature / pressure ratio, and reasonable corrosion data

When the ball valve is closed, there is still pressurized fluid inside the valve body

Before maintenance: release the pipeline pressure and leave the valve in the open position; disconnect the power or air source; disengage the actuator from the bracket

The pressure on the upstream and downstream pipes of the ball valve must be verified before the disassembly operation can be performed.

During disassembly and reassembly, care must be taken to prevent damage to the sealing surfaces of the parts, especially non-metallic parts. Special tools should be used when removing the O-rings

The bolts on the flange must be tightened symmetrically, gradually and evenly during assembly

The cleaning agent should be compatible with rubber parts, plastic parts, metal parts and working medium (such as gas) in the ball valve. When the working medium is gas, gasoline (GB484-89) can be used to clean metal parts. Non-metal parts are washed with pure water or alcohol

Non-metal parts should be removed from the cleaning agent immediately after cleaning, and should not be soaked for a long time

After cleaning, it needs to be assembled after the wall cleaning agent is volatilized (can be wiped with silk cloth not soaked with cleaning agent), but it must not be left for a long time, otherwise it will rust and be polluted by dust

New parts also need to be cleaned before assembly

During assembly, metal chips, fibers, grease (except for the specified use), dust and other impurities, foreign matter, etc. should not be allowed to contaminate, adhere or stay on the surface of the part or enter the inner cavity. Then tighten the stem nut.

Note: Don't lock too tightly, usually lock it again for 1/4 to 1 turn, the leakage will stop.

A), disassembly

Keep the valve in a half-open position to flush and remove the dangerous substances that may exist inside and outside the valve.

Close the ball valve, remove the connecting bolts and nuts on the flanges on both sides, and then completely remove the valve from the pipeline.

Disassemble the driving device in sequence-the actuator, the connecting bracket, the lock washer, the stem nut, the butterfly spring, the Glam, the wear-resistant sheet, and the stem packing.

Remove the body cover connecting bolts and nuts, separate the bonnet from the valve body, and remove the bonnet gasket.

Make sure the valve ball is in the "off" position, which makes it easier to remove it from the valve body and then remove the valve seat.

Push the valve stem from the middle hole of the valve body until it is completely removed, and then remove the O-ring and the packing under the valve stem.

Note: Be careful to avoid scratching the surface of the valve stem and the sealing part of the valve body stuffing box.

B), reassembly

Clean and inspect the removed parts. It is highly recommended to replace the seals such as the valve seat and bonnet gasket with a spare parts kit.

Assemble in the reverse order of disassembly.

Cross-tighten the flange connection bolts with the specified torque.

Tighten the stem nut with the specified torque.

After installing the actuator, input the corresponding signal to drive the valve core to rotate by turning the valve stem to make the valve to the open and closed positions.

If possible, perform pressure seal testing and

(1) Dismantling and disassembling operations must be carried out after confirming that the pressure on the upstream and downstream pipes of the ball valve has been relieved.

(2) Non-metal parts should be removed from the cleaning agent immediately after cleaning, and should not be soaked for a long time.

(3) The bolts on the flange must be tightened symmetrically, gradually and evenly during assembly.

(4) The cleaning agent should be compatible with rubber parts, plastic parts, metal parts and working medium (such as gas) in the ball valve. When the working medium is gas, you can use gasoline (GB484-89) to clean metal parts. Non-metal parts should be cleaned with pure water or alcohol.

(5) Each single ball valve part disassembled can be cleaned by dipping. Metal parts with non-decomposed non-metal parts can be scrubbed with a clean and fine silk cloth impregnated with cleaning agent (to prevent the fibers from falling off and sticking to the parts). When cleaning, all grease, dirt, glue, dust, etc. that adhere to the wall must be removed.

(6) When disassembling and reassembling the ball valve, care must be taken to prevent damage to the sealing surfaces of the parts, especially non-metal parts. Special tools should be used when removing the O-rings.

(7) After cleaning, it must be assembled after the wall cleaning agent is evaporated (can be wiped with silk cloth not soaked with cleaning agent), but it must not be left for a long time, otherwise it will rust and be polluted by dust.

(8) New parts should also be cleaned before assembly.

(9) Lubricate with grease. The grease should be compatible with the ball valve metal materials, rubber parts, plastic parts and working medium. When the working medium is gas, for example, special 221 grease can be used. Apply a thin layer of grease to the surface of the seal installation groove, apply a thin layer of grease to the rubber seal, and apply a thin layer of grease to the sealing and friction surfaces of the valve stem.

(10) Metal fragments, fibers, grease (except those specified for use) shall not be allowed to contaminate, adhere or stay on the surface of parts or enter the inner cavity during assembly.

Advantages: has the lowest flow resistance (actually 0); can not be stuck during work (without lubricant), so it can be reliably used in corrosive media and low boiling point liquids; in the larger It can be completely sealed within the range of pressure and temperature; It can realize rapid opening and closing, and the opening and closing time of some structures is only 0.05 ~ 0.1s, so as to ensure that it can be used in the test bench automation system. When opening and closing the valve quickly, the operation is shock-free. The spherical closure can be automatically positioned at the boundary position; The working medium is reliably sealed on both sides; When fully open and fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, so the medium passing through the valve at high speed will not Causes erosion of the sealing surface; compact structure and light weight, it can be considered as the most reasonable valve structure for low temperature media systems; valve body symmetry, especially the welded valve body structure, can well withstand the stress from the pipeline The closing part can withstand the high pressure difference when closing. Ball-welded ball valve can be directly buried in the ground, so that the internal parts of the valve are not eroded, and the maximum service life is up to 30 years. It is the most ideal valve for oil and gas pipelines.
Disadvantages: Because the main valve seat sealing material of the ball valve is polytetrafluoroethylene, it is inert to almost all chemicals, and has a small coefficient of friction, stable performance, not easy to age, wide temperature range and seal Comprehensive performance with excellent performance. However, the physical characteristics of PTFE, including higher expansion coefficient, sensitivity to cold flow, and poor thermal conductivity, require that the design of the valve seat seal must be based on these characteristics. Therefore, when the sealing material becomes hard, the reliability of the seal is impaired. Moreover, polytetrafluoroethylene has a low temperature resistance level and can only be used at temperatures below 180 ° C. Beyond this temperature, the sealing material will age. In the case of long-term use, it is generally used only at 120 ° C. Its regulating performance is worse than that of globe valves, especially pneumatic valves (or electric valves).