A detailed introduction to the standard opening and closing operation procedures of forged steel ball valves

I. Preparations Before Operation

Inspection items and requirements

Valve status confirmation: Confirm that the valve is currently in the fully open or fully closed position and observe the position indicator or limit pointer

Visual inspection: There should be no external leakage, rust or mechanical damage at the valve body, valve stem, packing gland and flange connection

Operating space: There are no obstacles around the handle or handwheel, and the operator's position is stable

Pipeline status: Ensure that the pressure difference between the upstream and downstream is within the allowable operating range. It is strictly prohibited to force operation under a huge pressure difference before and after the valve

Actuator (if any) : Confirm that the air source/power supply is normal, the set air pressure of the filter pressure reducing valve is correct, and the lubrication system is normal

Ii. Manual Operation Process

Handle operation

Open the valve

Confirm that the valve is currently in the closed position (with the handle perpendicular to the pipe axis).

Hold the handle with one or both hands and apply the torque steadily.

Rotate the handle counterclockwise by 90° until it is parallel to the pipe axis.

Observe the position indicator to confirm that the valve is fully open.

Check that there is no leakage at the valve stem and packing.

Close the valve

Confirm that the valve is currently in the open position (with the handle parallel to the pipe axis).

Rotate the handle clockwise by 90° until it is perpendicular to the pipe axis.

Stop applying force after the handle is in place. Do not forcibly rotate over the position.

Observe the position indicator to confirm that the valve is fully closed.

Lock the handle (if equipped with a locking device) to prevent misoperation.

Worm gear operation

Open the valve

Confirm that the position indicator of the worm gear box points to "CLOSED".

Turn the handwheel smoothly and rotate it in the valve opening direction marked on the worm gear box.

Keep rotating until the position indicator points to "OPEN" and the handwheel cannot continue to rotate in the same direction.

Turn the handwheel in the reverse direction by 1/4 to 1/2 turns to release the meshing stress of the worm and prevent thermal expansion and jamming.

Close the valve

Confirm that the position indicator points to "OPEN".

Turn the handwheel smoothly in the direction of valve closing marked on the worm gear box.

Keep rotating until the position indicator points to "CLOSED", and stop when the handwheel torque increases significantly.

Rotate in the reverse direction by 1/4 to 1/2 turns to release the stress.

Lock the handwheel (if equipped with a locking device).

Key Warning

The use of extension rods is strictly prohibited: The designed torque of the worm gear box has already matched the valve requirements. Extension rods can cause overload of the worm gear, pitting on the tooth surface, and broken teeth.

Excessive reverse rotation of the handwheel is strictly prohibited: Rotation is only used to release the meshing stress of the worm. Excessive rotation will cause the ball to deviate from the fully closed position, resulting in internal leakage.

Iii. Pneumatic Operation Process

Remote activation

The DCS/PLC issues the start command.

When the solenoid valve is energized, compressed air enters the open side of the cylinder.

The piston drives the transmission mechanism to rotate the ball to the fully open position.

The limit switch feeds back a "fully open" signal to the central control room.

Confirm that the valve action time complies with the design requirements.

Remote shutdown

The DCS/PLC issues a shutdown command.

When the solenoid valve loses power, the cylinder opens and exhausts on the side.

Single-acting spring return or double-acting reverse gas supply can push the ball to the fully closed position.

The limit switch feeds back a "fully off" signal to the central control room.

On-site manual emergency response

Cut off the gas supply and confirm that the actuator has been depressurized.

Disengage the clutch between the pneumatic actuator and the worm gear box (if equipped).

Manually open and close the valve according to the worm gear operation process.

After the operation is completed, reset the clutch and restore the air supply.

Iv. Electric Operation Process

Remote activation

The DCS issues an activation command.

The contactor is engaged, and the motor starts to rotate in the forward direction.

The valve stem is driven by the reduction mechanism, and the ball rotates to the fully open position.

When the limit switch or electronic torque detection is in place, the power supply to the motor is automatically cut off.

The position transmitter feeds back a "fully open" signal to the central control room.

Remote shutdown

The DCS issues a shutdown command.

The motor starts in reverse.

When the sphere rotates to the fully closed position, the torque switch automatically cuts off the power upon detecting the set torque.

Feed back the "all off" signal to the central control room.

On-site operation

Switch the actuator control mode to "LOCAL/LOCAL".

Operate through the "OPEN/CLOSE" button on the in-place panel.

Observe the local position indicator to confirm that it is in place.

After the operation is completed, switch back to "REMOTE".

Special precautions for electric operation

Torque protection: The turning torque value of the electric actuator has been set at the factory. During operation, it is strictly prohibited to increase it without authorization, otherwise the valve seat sealing surface will be damaged.

Overheat protection: The continuous opening and closing times of the S2 duty motor are limited. Frequent operation and overheating will trigger thermal protection and automatically shut down.

Emergency power failure: Valve position retention when power is cut off. In case of emergency shutdown, the handwheel should be used for manual operation.

V. Safety Warnings

Prohibited items and consequences

It is prohibited to forcibly open the sealing surface under full pressure difference to avoid erosion damage. Excessive torque may cause the valve stem to break

Do not use the extension rod or strike the handle to deform the valve stem, break the worm gear or crush the sealing surface

Excessive reverse rotation is prohibited for the ball to shift to the fully closed position, which may cause internal leakage of the valve

It is prohibited to adjust the limit bolts at will. If the limit fails, the ball will be out of position or not closed properly

It is strictly prohibited to disassemble the packing gland under pressure as the medium may spray out and cause personal injury

Vi. Inspection after operation

Confirm that the position indicator is consistent with the actual valve status.

Check that there is no external leakage at the valve stem packing and the valve body connection.

Check that there is no leakage in the air path of the pneumatic actuator and the oil level of the three-piece oil mist lubricator is normal.

Check that the operating current of the electric actuator is within the normal range, and there is no abnormal vibration or noise.

Record the operation time, operator and valve status, and incorporate them into the operation log.