- Features and Application
Ball valve means that the closure (ball) rotation rounds the axes of stem to achieve open and/or close. It is installed in the pipeline as medium’s cut/off device, regulating device and it also can be used to change flow direction. It has features in simple construction, excellent seat sealing performance, small flow resistance and easy operation etc.
Double Block and Bleed
Seat is designed with inlet seal construction, which has the functions of bi-direction seal and automatic pressure relief. (Unusually rising in cavity pressure, See the following figures). The seat inserted appropriate polymer (e.g. macromolecule material NYLON) is floating with spring loaded, at close position, seat face always keep a tight contact with ball, ensuring a tight bubble free valve both under high differential pressure and low differential pressure. Upstream: The spring loaded seat can be moved along the longitudinal axis of the valve, upstream pressure P is exerted on A2, this will engender a direction force on A1, the force exerted on A2 is greater than that on A1, the remaining differential force X pushes the seat tightly seal on to the ball. Downstream: As pressure Pb increasing, the force exerted on A3 is greater than that on A4, this will engender a differential force X2, move the seat against the action of the springs away from the ball surface, so that relive the excessive pressure, after that, the seat returned to the ball under spring action.
Emergency Sealant Injection
Valve is designed with a subsidiary seat emergency seal system, as the illustration. In case soft seat is damaged, or soft seat can’t seal in an emergent, emergency seal can be done by injection of the sealant into this subsidiary system. If necessary, the seat area can be flushed and lubricated by this system. Also, it is available for the stem.
Fire safe construction
According to the service conditions and user’s request, the ball valve is designed with fire safe construction conforming to API 607. In case soft seat are decomposed duo to extremely high temperature in fires, fire safe can prevents the leakage.
Antistatic Construction
When rotation of the ball, the friction between ball and seat ring will engender a static electricity gathered on the ball. To prevent the static spark, valve is designed with an antistatic device to transmit out the spark.
Block and Drain
When valve at the closed position, the seats cut off the flow, the dirt in body cavity can be drained through this block and drain device.
Locking Device
Valve is designed with a Locking device both at the fully open and fully closed position to prevent unnecessary or accidental valve operation, especially for the pipeline handled flammable medium and for the outdoor pipeline system.
Corrosion Resistance Design
Wall thickness of the body has a corrosion allowance, stem, trunnion, ball, and seats and bottom caps are treated with ENP as per ASTM B733 and B656. Further more, other anti-corrosion materials are available. Valve external coating adopts the paint produced by Relia Valve can meet various ambient requirements.
Shipping and storage
1、Preparation before transportation
Valve end passage and stem exposed surface are important place, the following measures shall be done:
(a) Clean the dirt inside the valve, keep valve inside cleaning and dryness.
(b) Machined and exposed surface shall be coated with antirust oil.
(c)Valve’s closure (ball) shall be in the fully closed position.
2、Transit
While valve transit shall be careful, not allowed rudely throw down, especially for the big size valves, the handwheel and stem shall not allowed as the lifting lug.
3、Storage
(a) Clean the dirt inside the valve, keep valve inside cleaning and dryness.
(b) Machined and exposed surface shall be coated with antirust oil.
(c)Valve’s closure (ball) shall be in the fully closed position.
2、Transit
While valve transit shall be careful, not allowed rudely throw down, especially for the big size valves, the handwheel and stem shall not allowed as the lifting lug.
3、Storage
What should notice to during storage is usually same as that during the preparation. But time factor is very important; generally, the storage time is depended on the warranty period of seat ring material. If want to extend the storage time for several weeks or months, then will spend funds to improve the storage condition. Valve usually store indoor, if valve have to be stored outdoor, then valves shall be covered with waterproof protectors and keep the valves leave the ground.
Installation
1．7 Installation is the key to determine the valve’s service life. The improper installation will make valve’s performance drop. Therefore, the following points shall be confirmed before the installation.
- Removal of the package, comparison with the material list and specification, check the label or nameplate.
- Please pay more attention to the caution labels attached on the valve, and take proper measures.
- Check the flow direction arrow on the body, if have, please install the valve as per the arrow direction.
- Checks if the valve inside is clean, no dirt and corrosive. Removing the special wrappage, such as the disc protector.
- Before the installation, check if the pipe is lean and have no the dirt.
2、The installation of flanged end valve with the pipeline
The seal performance of the pipe flange connection is depended on the compressive distortion of the gasket that installed between the companion flanges. Bolting connection resulting a mechanical acting force, which not only need to resist the normal pressure that can make the bolting connection loose, but also need to keep a necessary compressive stress exerted on the gasket. In order to ensure a perfect connection, please note the following points:
(a) Check the flange sealing face, if found a defective that can cause leakage (e.g. a deeper groove or the surface impress), repair these before the installation.
(b) Check if the dimension, length and material of the bolt is suitable for the service condition.
(c) ASME B16.5; Check if the gasket material is correct.
(d) Check the gasket ability resisting the defective.
The seal performance of the pipe flange connection is depended on the compressive distortion of the gasket that installed between the companion flanges. Bolting connection resulting a mechanical acting force, which not only need to resist the normal pressure that can make the bolting connection loose, but also need to keep a necessary compressive stress exerted on the gasket. In order to ensure a perfect connection, please note the following points:
(a) Check the flange sealing face, if found a defective that can cause leakage (e.g. a deeper groove or the surface impress), repair these before the installation.
(b) Check if the dimension, length and material of the bolt is suitable for the service condition.
(c) ASME B16.5; Check if the gasket material is correct.
(d) Check the gasket ability resisting the defective.
(e) Work carefully to ensure the companion flange has a good symmetric center. The thread part of the bolt shall be coated with lubricant. Bolts shall be fastened orderly while assembling, ensuring the contact surface between flange and gasket parallelism and smoothness. Bolts shall be fastened orderly and equably to avoid the flange distortion. Use of moment wrench can help ensuring the correctness of the flange bolting connection and smoothly fastening.
The parallelism and concentricity of the flanges are especially important while installation of the valve on to the pipeline. Please consider, if the companion flanges are not parallel, then will cause the distortion. Especially for the large diameter pipeline, the engineer should take this problem into consideration, if necessary, shall take the remedial measures.
Note: As the above mentioned, bolting connection shall be fastened by moment wrench. In case the torque is fluctuating during the operation, then this bolt has been bended, replacement and rejection is required.
The parallelism and concentricity of the flanges are especially important while installation of the valve on to the pipeline. Please consider, if the companion flanges are not parallel, then will cause the distortion. Especially for the large diameter pipeline, the engineer should take this problem into consideration, if necessary, shall take the remedial measures.
Note: As the above mentioned, bolting connection shall be fastened by moment wrench. In case the torque is fluctuating during the operation, then this bolt has been bended, replacement and rejection is required.
Operation and Maintenance
Pipeline china ball valve is a special product consisting of a series of rotation components and wearability components. To get a satisfactory service performance, then need to keep well care for the machined surface.
Under the normal operation condition and accord with the pressure, medium and temperature, the continuous service life is at least 3 years.
1、Operation
Most of the valves are operated through the linearity movement or the rotation of handwheel, wrench and handle etc, please careful and don’t so quickly or slow, and the operating force shall be exerted at a moderate distance.
At the closed position, the closure (ball) shall be correctly contacted with seats.
Ball valve need the closures have a correct contact to ensure the tight sealing. While open or close the valve, please make sure that the valve has been fully open or close according to the position indicator.
(a) The materials of seats and packing are the polymers. It is electric-pneumatic insulation between ball and stem, so, ball valve has antistatic devices, one is installed between the stem and ball, and another one is between the stem and body.
Under the normal operation condition and accord with the pressure, medium and temperature, the continuous service life is at least 3 years.
1、Operation
Most of the valves are operated through the linearity movement or the rotation of handwheel, wrench and handle etc, please careful and don’t so quickly or slow, and the operating force shall be exerted at a moderate distance.
At the closed position, the closure (ball) shall be correctly contacted with seats.
Ball valve need the closures have a correct contact to ensure the tight sealing. While open or close the valve, please make sure that the valve has been fully open or close according to the position indicator.
(a) The materials of seats and packing are the polymers. It is electric-pneumatic insulation between ball and stem, so, ball valve has antistatic devices, one is installed between the stem and ball, and another one is between the stem and body.
(b) For the combustible medium, soft-seated ball valve shall provide with a subsidiary sealing system.
Because ball valve is 1/4 turned valve, fluid pressure will possibly generate a large open torque or closed torque exerted on the closures. If don’t take a powerful control, valve will be forced to suddenly open and close, even generate the “water hammer”, destroy valve’s construction.
Because ball valve is 1/4 turned valve, fluid pressure will possibly generate a large open torque or closed torque exerted on the closures. If don’t take a powerful control, valve will be forced to suddenly open and close, even generate the “water hammer”, destroy valve’s construction.
- Maintenance
Valve is a mixed construction by the pressure vessel and operating mechanism, require to its maintenance that should not only consider the accidental open and close, and also consider the valve most of the time is in an immovable and pressure loaded status.
If valve stick on one position no movement a long time, then valve’s operability will be down in a way, this is caused by the packing ageing, motion components wearing or the dirt accumulation. In some working occasion, need to perform a periodicity plan or a fully circulation plan.
Stem leakage is often caused by the packing abrasion. Generally this can be remedied through fastening the packing gland. Packing force to high possibly result in rising the stem friction, stem operating is difficult, and expediting the packing abrasion. Under a severe service condition, the evaluation of the sealing effectiveness and repair is out of the range specified in this manual.
Valve external surface is easy for inspection and maintenance.
If valve stick on one position no movement a long time, then valve’s operability will be down in a way, this is caused by the packing ageing, motion components wearing or the dirt accumulation. In some working occasion, need to perform a periodicity plan or a fully circulation plan.
Stem leakage is often caused by the packing abrasion. Generally this can be remedied through fastening the packing gland. Packing force to high possibly result in rising the stem friction, stem operating is difficult, and expediting the packing abrasion. Under a severe service condition, the evaluation of the sealing effectiveness and repair is out of the range specified in this manual.
Valve external surface is easy for inspection and maintenance.
Common Malfunctions, Reasons and Repair Methods
| Malfunction | Reasons | |
| Packing leakage |
1) Gland doesn’t be fastened adequately.
2) Packing ring is not enough.
3) Packing is out of the life or effectless packing.
|
1) Fix the bolts.
2) Adds the packing rings.
3) Use of the new packing.
|
| Seat leakage | 4) Sealing face adhere with the dirt or sealing face is damaged. | 4) Cleaning or repair the sealing face or replacing the seal component. |
| Gasket leakage | 5) Bolts have no pretightening force. | 5) Fastening or pretightening the bolts. |
| Valve driving is not agile or closures are not working. |
6) Packing is too tight.
7) Gland is not in correct position.
8) Driving mechanism or connection components are damaged.
9) Stem has been distorting.
|
6) Properly loosen the gland bolts.
7) Adjusting the gland.
8) Disassembling and repair the driving mechanism or connection components.
9) Calibrating the stem.
|
This is from:Ball Valves Operation & Maintenance Manual
