A brief discussion on the primary task of operators in chemical enterprises – inspections

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Those in the dry chemical industry know that inspections are always the top priority. Work can be paused for a while, but the inspection tasks that need to be carried out throughout the day must not be stopped. Next, I will discuss several aspects of inspection, in the hope that it will be helpful to everyone. I. Monitoring DCS screens – Operators oversee the operation of the equipment through the DCS system. It is crucial to closely monitor the operating conditions reflected on the DCS, so that operators can take proactive measures to ensure the safe and efficient operation of the plant. 1. Unstable operating conditions during shift handover: Seize any conditions that may stabilize the situation, at least to control it until the equipment can be restored smoothly. 2. Inspection and comparison under normal operating conditions: Check the controller’s output and compare it with the normal position. The result can indicate whether the rotating equipment is transporting the process fluid properly ； Strengthen communication between internal and external teams to identify the root causes of fluctuations. 3. Record all actions: All operational actions taken for correction must be documented, and all adjustments made must be recorded. 4. Tracking adjustments made: Monitoring whether any process adjustments achieve the desired results ； Check all process parameters and conditions that are affected by the adjustments, in order to determine whether they are developing as expected ； For the operation of the tank, set a stop point and an estimated completion time. 5. Handover to the next shift: Emphasize the situations that require special attention ； Describe the actions taken by a class and the reasons behind them ； Describe the expected changes that will occur next. II. Inspection of centrifugal compressors 1. If abnormal noises or vibrations are detected, pay special attention to heat-generating equipment: identify any differences in noise and vibration by listening or touching, and report them. 2. Check for leaks in the process fluid, lubricating oil, and seal oil systems. Note: During each lubricant inspection, the lubricant and seal oil systems must be checked: verify for any leaks at the connections of the compressor casing ； Check the shaft and bearings for signs of leakage ； For compressors sealed with seal oil, it is necessary to regularly inspect the seals to determine the leakage rate of the seal oil ； For compressors sealed with dry gas, it is necessary to monitor the seal gas control panel in order to determine the seal gas leakage rate and potential issues. 3. Check the liquid level at the sight glass of the suction tank: This is a cross-check to ensure that the liquid level gauge and controls in the suction tank are functioning properly, as liquid entrainment in the suction tank can cause serious damage to the compressor. 4. Check the oil return line sight glass: When the compressor is operating, there should be an adequate flow of lubricating oil in the compressor’s bearing housing. Note: The amount of oil flowing out of the thrust bearing housing is generally larger. 5. Ensure the lubrication system is working properly: The lubrication pressure is normal ； The pressure difference of the lubricating oil filter is normal ； The lubricating oil standby pump is not running but is in auto-start mode ； The lubrication oil pipe does not leak ； The lubricant temperature is within the normal range ； The safety valve shows no leakage and has not activated. 6. Check all on-site meters and instruments: Verify that the readings are normal and consistent with those of the electronic meters. 7. Record any abnormalities in the logbook: fill in a comparison record and explain the deviations; if they cannot be explained, an investigation must be conducted and a report submitted ； Hand over the reported or unreported issues at the end of the shift. III. Inspection of pipelines Water is the main cause of external corrosion of pipelines. Look for areas where water has accumulated, especially around the supports. Take measures to prevent accumulation around the support. Underground pipes are generally covered to prevent external corrosion. However, if the ground is wet, the possibility of external corrosion still exists. 1. Signs of external corrosion detected: cracks in the paint surface were found. Mark the damaged areas, clean them, and paint them to prevent further corrosion ； Pay attention to the insulated pipelines that are used intermittently. Check that no moisture has penetrated inside the insulation. 2. Identifying problems with underground pipelines: Check the areas where the pipelines enter the ground to see if there are any wrapping issues ； Signs of hydrocarbons emerging from underground have been detected. Note that a large amount of water leakage can cause the ground to collapse. 3. Check pipeline supports: Identify areas where water accumulation may lead to corrosion ； Check whether the support is in good condition and free from any lateral misalignment ； Check the support horseshoes to ensure that no brackets have fallen off ； Check that the pipeline guide allows free rotation of the horse shoe. 4. Pay special attention to steam pipes: be aware of water hammer. Check the condition of the strainer ； The leakage of superheated steam from flanges is invisible; the sounds produced range from a mild hissing to a harsh, high-frequency noise. It is necessary to isolate and repair the pipeline as soon as possible to prevent the steam from damaging the flange connections. 5. Check the valve: Verify whether there is any leakage from the valve packing ； Is the instrument air for the control valve in use? ； Are the upstream and downstream drain valves closed? ； Whether the valve is in the on state. IV. Inspection of insulation: It is not uncommon for the insulation around pipelines to be damaged, leading to fires. The reason is oil leakage, so it is necessary to check the integrity of the insulation. 1. Inspector’s inspection of pipeline insulation: Check whether the metal coating is loose ； Check whether the insulation is sunken (someone might step on it) ； Checking for leaks in the valve packing will prevent leakage into the insulation ； Prevent water from entering the insulation. 2. Equipment insulation inspection: Check whether the insulation tape is broken ； Check whether the adhesive has cracked, allowing water to enter the insulation ； The equipment needs to be repaired, and the damaged coating must be replaced. 3. Inspection after the storm: Check that the insulation covering has not been torn apart by the wind, especially on the tank body. V. Inspection of the pump 1. Check the lubricating oil level and quality of the pump ； 2. Check for leaks in the mechanical seal ； 3. Check the motor current ； 4. Check the pump’s outlet pressure and seal oil pressure ； 5. Check the temperature and vibration of the bearing housing and motor; the equipment should make no abnormal noises ； 6. Check whether the pump’s cooling water is functioning properly ； 7. Check the preheating status of the standby pump. 8. Perform pump rotation checks on both the standby pump and the pumps that are not in use ； 9. Keep proper records of pump barring and operation. VI. Inspection of the safety valve 1. Check for internal leakage: If the temperature of the outlet pipeline of the safety valve is the same as that of the upstream pipeline, or if the pipeline downstream of the outlet freezes, it indicates internal leakage in the safety valve. 2. Other characteristics of internal leakage in safety valves: Check torch emissions ； Check for liquid accumulation in the buffer tank. 3. Check the integrity of the Interlock: Verify that the Interlock is properly locked. 4. Inspection after the safety valve activates: Check whether the safety valve has returned to its original position ； Check whether the exhaust pipeline is displaced. Identify abnormal phenomena by looking, listening, touching, and smelling. Working in a chemical plant, risks can be controlled, and this first requires careful inspections by the operators.