Instrumentation: [Weekly Question] Discussion question for Week 10 of 2011: What are the precautions that instrument technicians should take when working on site?

When repairing instruments at the site, it is necessary to inform the process engineering team; for example, when repairing valves, the team should be asked to set up a bypass, and when removing the valve base, it is important to determine whether the pipeline contains liquid or gas, as well as whether it is toxic or harmful to the environment. When disconnecting signal wires, it is essential to check with the process engineering team regarding any interlocks, as this could trigger alarms in the DCS system. It is necessary to ensure that the instruments are operating within normal parameters before leaving the job site. Detailed records should be kept for future reference

This post was last edited by denghl on 2012-11-26 at 22:58. 1. Understand the properties of the working medium, such as temperature, pressure, and characteristics of the fluid. 2. Wear appropriate protective clothing and safety gear; take proper safety measures when assembling or disassembling equipment. 3. Check whether the device is operating in automatic mode or with interlocks; disable them if necessary. 4. Have a process engineer present while working, and follow their advice. 5. When two or more people are working together, there must be someone to supervise them. 6. Avoid reckless behavior and working in violation of safety regulations.

This post was last edited by denghl on 2012-11-26 at 22:58. Reply to 1# Baghdad: 1. When using the ohm meter function of a multimeter, be sure not to take measurements while the device is powered on. 2. When using a logic probe or oscilloscope to detect signals, be careful not to let the probes make contact with two measurement pins at the same time, as this essentially creates a short circuit when power is applied. 3. When testing the filter capacitors in the power supply, the positive and negative terminals of the electrolytic capacitor should first be short-circuited. Do not use the test lead wires as a substitute for wires to discharge the capacitor during this process, as this can easily cause the core wire to burn out. A 220V, 60–100W lamp with a bulb lead can be used, connected across the capacitor; the bulb will flash at the moment of discharge. 4. When troubleshooting instrument faults in humid environments, it is necessary to use a multimeter to check whether the various points on the printed circuit are conductive, as the main issue in such situations is copper foil corrosion. 5. When servicing the internal circuits of instruments, if the contacts of the components and the circuit board are coated with insulating varnish, a regular sewing needle can be soldered to the probes of a multimeter in order to pierce through the varnish layer and measure the parameters at various points, thereby avoiding the need to remove a large area of the varnish layer. 6. Do not plug or unplug various control boards and plugs while they are powered on. Because when the power is on, plugging in or removing the control board generates a strong induced electromotive force; at this time the reverse voltage is very high, which can easily damage the corresponding control board and plug. 7. During maintenance, do not strike or touch things randomly to avoid exacerbating the fault and making it worse. 8. When removing or adjusting instruments, their original positions should be recorded for restoration. 9. When repairing precision instruments, if small parts are accidentally sent flying, one should first determine where they might have fallen; there’s no need to search around randomly. Magnet scanning and visual scanning can be used to locate them. In short, in the work of repairing instruments and meters, one must first understand their basic principles and acquire knowledge and skills related to electronics. It is also necessary to have available all technical documents such as manuals and diagrams for these instruments and meters. Additionally, developing good working habits is essential in order to improve efficiency and reduce errors in the repair process.

This post was last edited by denghl on 2012-11-26 at 22:58. First, contact the process team; after the work is completed, inform the process team so that they can give their confirmation. For devices with interlocks, the interlocks must be disabled before processing

This post was last edited by denghl on 2012-11-26 at 22:58. First, contact the process team to confirm whether it is a chain reaction, whether the medium is toxic, and what the pressure and temperature levels are For manual notifications, it should be done manually: has the valve been removed, and is the backflow preventer turned on? Has it been discharged? A work order is required for this work.

Reply to 1#: When repairing instruments at the Baghdad site, it is necessary to inform the process team. If valves are to be repaired, the process team should be asked to set up a bypass; when removing a valve base, it is important to determine whether the pipeline contains liquid or gas, and whether it is toxic or harmful to the environment. When removing signal wires, it is necessary to check with the process team to see if there are any interlocks, as this could trigger alarms in the DCS system. After repairs, it is essential to confirm that the instrument’s operating parameters are normal before leaving. Detailed records should be kept for future reference

This post was last edited by denghl on 2012-11-26 at 22:59. 1. When repairing equipment, the process must be informed； And there are specific solutions. 2. The working environment must be confirmed. Is there any cross-operation? ； Are there any sources of danger, such as flammable (toxic or harmful) gases or substances, and are the process safety conditions suitable for construction? 3. Be careful during the operation process to avoid disrupting the manufacturing workflow. Pay close attention to any unexpected factors that arise during the task.

This post was last edited by denghl on 2012-11-26 at 22:59. First, it’s necessary to determine whether the instrument can be disassembled for repair; when working in areas under pressure, be careful when loosening screws. Pay attention if there are any materials present or if anything unusual occurs – safety comes first. Once, while removing the valve core of a cut-off valve, the core popped out; it turned out that the operator thought the steam valve had been fully closed, but in reality it couldn’t be fully closed. Fortunately, I was cautious. Also, when working, one must not stand in front of the flange connections or pressure release ports. Before starting work, think ahead about the tools that will be needed, and as a last resort, consider whether spare parts are available in case repairs cannot be completed internally. Otherwise, after removal, temporary measures such as blind plates are needed. To remove the stitches, the threads need to be separated and wrapped properly~ Things must be done perfectly~ Resolved completely~ Don’t seek convenience~ Because it will still be your responsibility if it happens again

Be careful, including regarding personal safety and production safety. Observe the on-site environment and carry out operations appropriately. Understand the media and process parameters measured by various instruments.

This post was last edited by denghl on 2012-11-26 at 22:59. 1. The instruments work in close coordination with the process； 2. Coordinate and pay attention between the site and the control room ； 3. The ledger entries are timely and detailed. 4. Great attention is paid to safety on site, with appropriate protective measures in place. Let’s talk about these first