Inspection requirements for instruments and control systems

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I. Pressure and differential pressure transmitters
1. Check whether the pressure and differential pressure transmitters are in good condition.
2. Check for any leakage points on the instrument’s measurement wires and at the static sealing points.
3. Verify that the valves used for isolation, venting, and drainage of the instrument’s measurement wires as well as those for the flushing/isolation fluid lines are in the correct position, and that the vent caps/nuts are properly tightened.
4. Check the insulation and heating arrangements (if any) for the instrument’s measurement wires.
5. Inspect the waterproofing of the pressure and differential pressure transmitters.
6. Check whether there are any hazards such as vibration affecting the pressure and differential pressure transmitters.
7. Verify that the readings displayed by the transmitters match those shown by the local measuring instruments (such as pressure gauges and differential pressure gauges).

II. Pressure/differential pressure switches
1. Check whether the pressure/differential pressure switches are in good condition.
2. Check for any leakage points on the instrument’s measurement wires and at the static sealing points.
3. Inspect the waterproofing of the pressure/differential pressure switches.
4. Check whether there are any hazards such as vibration affecting the pressure/differential pressure switches.
5. Verify that the valves used for isolation, venting, and drainage of the instrument’s measurement wires as well as those for the flushing/isolation fluid lines are in the correct position, and that the vent caps/nuts are properly tightened. 6. Check the insulation and heating of the measurement leads (if any).
III. Temperature Transmitter
1. Check whether the temperature transmitter is in good condition.
2. Check the waterproofing of the temperature transmitter.
3. Check whether there are any hazards such as vibration affecting the transmitter.
4. Check whether the measurement value displayed by the temperature transmitter matches that of the local measuring instrument (such as a bimetallic thermometer).
IV. Float Level/Boundary Level Transmitter
1. Check whether the float level/boundary level transmitter is in good condition.
2. Check for any leaks in the float level/boundary level transmitter.
3. Check whether the measurement value displayed by the transmitter matches those of the local indicating instruments (such as glass plate/glass tube/magnetic flap level gauges) as well as other measuring instruments at the same measurement point (such as double-flange transmitters/magnetic float transmitters). 4. Check whether the switch states of the float isolation valve and the vent/drain valves are correct, and whether the vent pipe caps/plugs are tightened properly. 5. Check the waterproofing condition of the float level/level-sensing transmitter. 6. Check whether there are any hazards such as vibration affecting the float level/level-sensing transmitter. 7. Check the insulation/heat retention/heating mechanism of the transmitter’s cylinder (if available).

V. Float Level/Level-Sensing Switches
1. Check whether the float level/level-sensing switches are in good condition. 2. Check for any leaks in these switches. 3. Check whether the switch states of the float isolation valve and the vent/drain valves are correct, and whether the vent pipe caps/plugs are tightened properly. 4. Check the waterproofing condition of the float level/level-sensing switches. 5. Check the gas phase condition at the upper part of the transmitter’s cylinder to determine if there is a “gas accumulation” issue. 6. Check the insulation/heat retention/heating mechanism of the transmitter’s cylinder (if available). 7. Check whether there are any hazards such as vibration affecting the float level/level-sensing switches.

VI. Ball Level Transmitters
1. Check whether the ball level transmitter is in good condition. 2. Check its waterproofing condition. 3. Check for any leaks in the transmitter. 4. Check the fixing condition of the weight slider in the ball level transmitter. 5. Check the transmission and lubrication conditions of the transmitter’s moving parts; apply high-temperature resistant lubricant as needed. VII. Mass Flow Meter
1. Check whether the mass flow meter is in good condition.
2. Check for any leaks in the mass flow meter.
3. Inspect the waterproof performance of the mass flow meter.
4. Examine the vibration of the mass flow meter along with the process pipeline.
5. Verify that the status alarms of the mass flow meter are functioning properly, and that its measurement functions are normal (e.g., whether flow rate, density, and temperature values are within the normal range).

VIII. Pipe Vortex Flow Meter / Pipe Turbine Flow Meter / Pipe Electromagnetic Flow Meter / Insertion-Type Electromagnetic Flow Meter
1. Check whether the pipe vortex flow meter/pipe turbine flow meter/pipe electromagnetic flow meter/insertion-type electromagnetic flow meter is in good condition.
2. Look for any leaks in these flow meters.
3. Inspect their waterproof properties.
4. Check that the status alarms of these flow meters are functioning properly, and that their measurement functions are normal (e.g., whether flow rate values are within the normal range).

IX. Ultrasonic Flow Meter
1. Check whether the ultrasonic flow meter is in good condition.
2. Inspect its waterproof performance.
3. Verify that the probe of the ultrasonic flow meter is securely connected and fixed.
4. Check that the status alarms of the ultrasonic flow meter are functioning properly, and that its measurement functions are normal (e.g., whether flow rate and velocity values are within the normal range).

X. Ordinary Control Valve
1. Check whether the control valve and its accessories are in good condition.
2. Verify that the air supply pressure for the control valve’s positioner/electrical converter is correct, as well as its waterproof performance.
3. Check for any leaks in the air supply and signal lines of the control valve, and ensure that all connections are secure.
4. Verify that the feedback rod of the control valve’s positioner is firmly connected to the valve stem, and that the signal air pressure corresponds to the valve’s opening degree.
5. Check for any leaks at the flanges and gaskets of the control valve.
6. Verify that the handwheel of the control valve is in the correct position.
7. Check whether there are any risks such as vibration associated with the control valve and its accessories.

XI. Control/Interlock Valve
1. Check whether the control/interlock valve and its accessories are in good condition.
2. Verify that the air supply pressure for the control/interlock valve’s positioner/electrical converter is correct, as well as its waterproof performance.
3. Check for any leaks in the air supply and signal lines of the control/interlock valve, and ensure that all connections are secure.
4. Verify that the feedback rod of the control/interlock valve’s positioner is firmly connected to the valve stem, and that the signal air pressure corresponds to the valve’s opening degree.
5. Check for any leaks at the flanges and gaskets of the control/interlock valve.
6. Inspect the installation and waterproofing of the solenoid valve used with the control/interlock valve.
7. Check the connection between the valve position feedback switch and the valve stem, as well as its waterproofing.
8. Check whether there are any risks such as vibration associated with the control/interlock valve.

XII. Interlock/On-Off Valve
1. Check whether the interlock/on-off valve and its accessories are in good condition.
2. Verify that the air supply pressure for the interlock/on-off valve is correct, and check for any leaks in the air supply and signal lines, ensuring that all connections are secure.
3. Check that the signal air pressure of the interlock/on-off valve corresponds to the valve’s opening degree.
4. Check for any leaks at the flanges and gaskets of the interlock/on-off valve.
5. Inspect the installation and waterproofing of the solenoid valve used with the interlock/on-off valve.
6. Check the connection between the valve position feedback switch and the valve stem, as well as its waterproofing.
7. Check whether there are any risks such as vibration associated with the interlock/on-off valve.

XIII. Hydrogenation Treatment XV Interlock Valve
1. Check whether the XV interlock valve and its accessories are in good condition.
2. Verify that the air supply pressure for the XV interlock valve is correct (for HARTMANN ball valves, the air supply pressure should be set to its maximum value). Also, check for any leaks in the air supply and signal lines, ensuring that all connections are secure.
3. Check that the signal air pressure of the XV interlock valve corresponds to the valve’s opening degree.
4. Check for any leaks at the flanges and gaskets of the XV interlock valve.
5. Inspect the installation and waterproofing of the solenoid valve used with the XV interlock valve.
6. Check the connection between the valve position feedback switch and the valve stem, as well as its waterproofing.

XIV. Self-Acting Control Valve
1. Check whether the self-acting control valve is in good condition.
2. Verify that there are no leaks in the pressure lead lines of the self-acting control valve, and that all connections are secure.
3. Check for any leaks at the flanges and gaskets of the self-acting control valve.
4. Check whether there are any risks such as vibration associated with the self-acting control valve.

XV. Radar Level Gauge
1. Check whether the radar level gauge and the indicator mounted beside the tank are in good condition.
2. Inspect their waterproof performance.
3. Check for any leaks in the radar level gauge.
4. Verify that the measurement values displayed by the radar level gauge and the indicator beside the tank are within the normal range, and check for any alarm messages.

XVI. Servo Level Gauge
1. Check whether the servo level gauge and the indicator mounted beside the tank are in good condition.
2. Inspect their waterproof performance.
3. Check for any leaks in the servo level gauge.
4. Verify that the measurement values displayed by the servo level gauge and the indicator beside the tank are within the normal range, and check for any alarm messages.

XVII. Combustible Gas/Toxic Gas Detection Transmitter
1. Check whether there are any abnormalities in the readings shown on the combustible gas/toxic gas detectors at the DCS control station.
2. Verify that the combustible gas/toxic gas detection transmitter is in good condition.
3. Inspect its waterproof performance, as well as the condition and proper functioning of the probe’s rain cover.
4. Check whether the installation height of the probe of the combustible gas/toxic gas detection transmitter meets the requirements.
5. Verify that the readings from the combustible gas/toxic gas detection transmitter are normal, and check for any alarm messages