Safety, taboos, and precautions for the maintenance of centrifugal pumps

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Safety, prohibitions, and precautions for the maintenance of centrifugal pumps I. Prohibitions and preparations before maintenance 1. Failing to cut off power and the medium – Prohibition: Starting maintenance without disconnecting the power supply, closing the inlet and outlet valves, or releasing pressure or emptying the medium. - Consequences: It may cause electric shock, injury from splashing media, or accidental activation of the equipment. - Correct procedure: - Turn off the power supply and hang a warning sign at the switch. - Close the inlet and outlet valves, open the drain valve to empty the medium, and install blind flanges to isolate the system if necessary. - For high-temperature medium pumps, they need to be cooled to room temperature before maintenance. 2. Failure to clean the work site and prepare tools – Prohibition: A messy repair site, insufficient tools, or failure to check the condition of the tools. - Consequences: loss of tools, damage to parts, incorrect or missing installation, or even leaving tools inside the equipment. - Proper procedure: - Clean the area to ensure it is tidy and organized. - Prepare all necessary maintenance tools, measuring instruments, and spare parts, and check their condition. 3. Lack of understanding of equipment condition – Prohibition: Failure to know the pump’s operating history, defect records, or to anticipate components that may fail. - Consequence: Accidents may occur during maintenance due to unexpected problems. - Proper operation: - Review the equipment operation records to understand the pump’s operating mode, internal structure, and the purpose of its components. - Prepare spare parts in advance for components that may be damaged, such as bearings and impellers. II. Prohibitions and Operating Procedures During Maintenance 1. Rough disassembly and assembly – Prohibited: Using hammers to strike, chisels to pry off bolts, or forcing parts to be lifted or pried apart. - Consequences: Damage to equipment parts, generation of sparks (which can cause explosions in flammable and explosive environments). - Correct procedure: - Use non-sparking tools such as copper rods and copper hammers. - When bolts are rusted, they can be cut with a saw, and soap water or glycerin can be used to assist in removal. - When removing for lifting, ensure that the lifting equipment has sufficient capacity to avoid overloading. 2. Unmarked or unrecorded – Prohibited: Failing to mark the parts or record the assembly sequence after disassembly. - Consequence: Chaos and mistakes during reinstallation, leading to equipment damage or abnormal operation. - Proper procedure: – For complex equipment such as multi-stage pumps, mark the parts in their original assembly order. - Small parts that are difficult to label (such as keys) can be placed together with impellers or vanes of the same grade. - Record key data during disassembly (such as balance disc clearance and rotor play). 3. Failure to inspect part defects – Prohibition: Reinstalling the part without checking for wear, cracks, corrosion, or erosion. - Consequence: The device fails again after being put into operation, potentially even leading to serious accidents. - Proper operation: - Check the wear, cracks, and fit clearance of key components such as the pump shaft, impeller, and bearings. - Non-destructive testing (such as ultrasonic testing) is carried out on shafts, impellers, etc. when necessary. - Measure the circular runout and clearances of various parts of the rotor, and perform dynamic balance verification if necessary. 4. Unisolated flammable and explosive environments – Prohibition: Using non-ventilated areas or non-explosion-proof tools in flammable and explosive environments. - Consequence: Causes fire or explosion. - Proper procedure: – For pumps handling flammable and explosive materials, ensure adequate ventilation before maintenance to keep the concentration of combustible gases below the lower explosion limit. - Use explosion-proof tools to avoid generating sparks. - Smoking or the use of open flames is strictly prohibited during maintenance. III. Prohibitions after maintenance and commissioning specifications 1. Failure to clean the site or leaving tools behind – Prohibition: Leaving debris or tools at the site after maintenance. - Consequence: The tool gets stuck or damages the equipment while it is in operation. - Correct procedure: - Clean the area to ensure no debris is left behind. - Inspect the inside of the device to ensure that no tools or parts are missing. 2. Misalignment or lack of tightening not checked – Prohibited: Starting the machine without checking the coupling alignment or without tightening the bolts. - Consequences: severe equipment vibration, bearing damage, or coupling failure. - Proper operation: - Check the coupling alignment to ensure that the radial and end-face clearances are within the specified limits. - Tighten all bolts to ensure there is no looseness. 3. No test run or starting under load – Prohibited: Starting without an idle test run or directly under load. - Consequences: equipment jamming, motor burnout, or pipe rupture. - Proper operation: - Conduct a no-load test run to check the pump’s direction of rotation, vibration, noise, and seal leakage. - Once normal operation is confirmed, gradually increase the load to the rated operating conditions while monitoring the operational parameters (such as flow rate, pressure, and current). IV. Contraindications in Special Environments 1. Underground pump maintenance – Contraindication: Failure to ensure ventilation or failure to follow procedures for entering confined spaces. - Consequences: Hypoxia or poisoning. - Proper operation: – Ensure good ventilation in the underground pump pit, and monitor the levels of oxygen and toxic gases. - Follow the confined space entry procedures and wear appropriate safety equipment. 2. Maintenance of high-temperature or high-pressure pumps – Prohibition: Performing maintenance before the pumps have been cooled to room temperature or before the pressure has been released. - Consequence: Burns or injury from medium splashing. - Correct procedure: - Wait for the pump to cool down to room temperature before performing maintenance. - Release pressure slowly to avoid medium splashing caused by sudden pressure changes. V. Prohibitions for Operator Actions 1. Operation by unauthorized personnel – Prohibition: Centrifugal pumps must not be operated by persons who have not received training or authorization. - Consequence: Improper operation leads to accidents. - Proper operation: – Only authorized and experienced personnel are allowed to operate the centrifugal pump. - Receive safety training before operation to become familiar with the equipment operating procedures. 2. Failure to wear protective equipment – Prohibited: Performing maintenance without wearing a safety helmet, protective goggles, gloves, etc. - Consequences: Injuries to the head, eyes, or hands. - Proper procedure: – Wear full protective equipment to ensure personal safety.