The tasks of an instrument technician

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The routine maintenance of process monitoring and control instruments is a very important task; it is a crucial element in ensuring safe and smooth production operations. The daily maintenance of instruments reflects the preventive approach of total quality management; instrument operators should carry out their maintenance tasks diligently to ensure the proper operation of the instruments. The daily maintenance of instruments mainly includes the following: (1) Routine inspections, (2) Regular drainage and refueling, (3) Periodic lubrication and anti-corrosion measures, (4) Frost prevention checks, (5) Fault troubleshooting. 01. Routine inspections: Instrument technicians generally have their own areas responsible for the maintenance of instruments. Based on the distribution of instruments in those areas, they determine the routes for routine inspections, carrying out such inspections at least once a day. Main contents of the routine inspection: 1. Consult the on-duty process personnel about the operation status of the instruments. 2. Check the instrument indications to see if they are normal. Verify whether the indications from the field primary instruments (transmitters) and the display instruments in the control room, as well as the values shown on the DCS operator stations, are consistent. Also check whether the output of the control loop matches the valve position of the control valve. 3. Check whether the 24V power supply output is normal (a dimmed output voltage indicator often indicates an abnormality). Also, verify whether the air source pressure falls within the required range (0.14 MPa, 0.35 MPa, etc.). Are the power voltage and torque of the electric control valve normal? 4. Check the insulation and heating condition of the instruments (especially in winter), by using a thermometer to take temperatures. 5. Check for damage and corrosion on the instrument body and its connections, including whether the flexible tube connections are loose or damaged. 6. Check for leaks at instruments and process interfaces. 7. For outdoor instruments, protective measures such as plastic bags should be applied in a timely manner when the environment is harsh; the condition of these protections should be checked to ensure there are no damages or losses. 8. Check the alarm interlock device to ensure it is in good condition. Regularly test the alarm interlock function and keep test records. 9. Check the integrity of the gauges. The condition of the instruments can be checked in accordance with the \"Equipment Maintenance and Repair Procedures\" issued by the Ministry of Chemical Industry. (1) The components are complete and meet the technical requirements: a. The components should be in good condition and of standardized specifications ； b. All fasteners must be in place and not loose ； c. The connectors should make good contact ； d. Terminal wiring should be secure ； e. The adjustable parts should be in the adjustable position ； f. The seal should be leak-free. (2) Operates normally and meets usage requirements: a. During operation, the instrument should achieve the specified performance indicators ； The display and output should be normal, with the error not exceeding the allowable error range of the instrument. b. Under normal operating conditions, the instrument reading should be between 20% and 80% of the full scale ； (3) Equipment and environment should be tidy and clean, meeting work requirements: a. The entire machine should be clean; b. Instrument pipelines and wiring should be neatly laid out and securely installed ； c. Check that the power supply for the emergency shut-off valve, the battery, the handle, the oil tank level, controller parameters, etc., are all in normal condition. 02. Regular draining and oiling: With the significant rise in the level of automation, the number of pneumatic actuators has also increased dramatically. Therefore, for routine maintenance, it is necessary to regularly drain and oil the air source treatment equipment. Common components of air source treatment equipment: Filters, which remove solid impurities and some moisture from the air source, thereby providing cleaner compressed air. Reducer, used to lower and stabilize the pressure of compressed air supplied by the air source. Oil mist lubricators add oil mist to the air used by pneumatic equipment, thereby lubricating the equipment. Routine maintenance: Filter: (1) Manually drain water – it must be drained before the water level reaches below the filter element; (2) Clean the filter element (by soaking, scrubbing, or backwashing) or replace it. If there are too many impurities, it becomes airtight. Pressure reducer: When adjusting the pressure, it should be increased gradually and evenly to the desired value, rather than being adjusted all at once. If there are no faults, no maintenance is needed. Oil mister: Used for refilling and adjusting the oil dripping rate; there is a twistable element on top that is used to adjust the dripping speed. Do not fill the cup more than to eight parts full. If there is an air leak in the gas source treatment equipment, it is abnormal; measures should be taken to seal it or replace it. 03. Regular lubrication and corrosion prevention: Regular lubrication and corrosion prevention are also part of the daily maintenance tasks for instrument technicians, but they are often overlooked in practice. The lubrication cycle should be determined based on specific circumstances. The instruments and components that require regular lubrication and corrosion protection are as follows: 1. Pneumatic cam flexure valves, pneumatic ball valves, pneumatic butterfly valves, rotating parts of electric actuators ； 2. Protection box, door hinges of the insulated box, fastening bolts of the wiring box. 3. In harsh environments, the bolts and nuts securing transmitters, control valves, valve positioners, and electro-pneumatic converters are prone to rust, making disassembly and reassembly difficult. 4. Rotating part of the feedback rod of the valve positioner in harsh environments. 5. Thermal resistors in harsh environments, as well as the bolts or screw threads on the cover of thermocouple junction boxes. 6. Connection parts between flexible tubes and instruments in harsh environments 04. Anti-freezing inspection: Inspecting the anti-freezing measures for instruments is one of the tasks in their routine maintenance. It is crucial for energy conservation, preventing instruments from being damaged by freezing, and ensuring the proper operation of the instrument measurement systems. Therefore, this is an essential aspect of instrument maintenance that must not be overlooked. This work is highly seasonal in nature; it involves checking whether there are any abnormalities in the medium inside the pressure transfer tubes of the gas tank level transmitters, as well as whether the insulation material has come loose. For certain instruments, it is necessary to inspect the heating systems in place, and to turn these heating systems on or off accordingly based on weather conditions, in order to prevent freezing while ensuring that the instruments function properly. 05. Fault Handling: Fault handling is an important part of the daily maintenance of instruments. It is necessary to address faults quickly and effectively, with seriousness and care, so as to avoid any potential issues. Any problems that cannot be resolved should be reported promptly for coordinated handling. Fault handling requires the proactive learning and experience accumulation of instrument operators; the \"Precautions for Starting and Stopping\" (attached) is provided as a reference for daily maintenance. When dealing with faults and performing maintenance on instruments, instrument technicians must prioritize safety above all else; there must be no risk to personal safety or disruption to the normal operation of production. The principle of safety first must be firmly upheld. Before starting any maintenance work, it is essential to be familiar with the process flow, and any instrument or equipment that needs to be disassembled must be handled only after obtaining permission from process engineers and under their supervision. Prevent safety accidents. Basic analysis and handling steps for faults in on-site instrument systems. The measurement parameters of on-site instruments generally fall into four categories: temperature, pressure, flow rate, and liquid level. Now, based on the different measurement parameters, we analyze the causes of various faults in field instruments. 1. First, before analyzing faults in on-site instruments, it is necessary to have a thorough understanding of the production process, manufacturing methods, and conditions related to the instrument system in question. It is also important to know the design scheme and intent behind the instrument system, as well as its structure, characteristics, performance, and parameter requirements. 2. Before analyzing and checking for faults in the on-site instrument system, it is necessary to obtain information from the operators on site regarding the production load and changes in the parameters of the raw materials. The recording curves of the faulty instruments should also be examined, and a comprehensive analysis conducted to determine the cause of the instrument failure. 3. If the instrument’s recorded curve is a straight line with no changes at all (a line with no variation is called a straight line), or if the curve, which was originally fluctuating, suddenly becomes a straight line ； The fault is likely in the instrumentation system. Since most of the current recording instruments are DCS computer systems, they have extremely high sensitivity, allowing them to respond very promptly to any changes in parameters. At this point, the process parameters can be manually adjusted to observe the changes in the curve. If there is no change, it can be concluded with certainty that there’s a problem with the instrument system ； If there are normal variations, it can be generally concluded that there is no major issue with the instrumentation system. 4. When changing process parameters, if it is observed that the recorded curve undergoes a sudden change or jumps to its maximum or minimum value, the fault often lies in the instrument system. 5. Before the fault occurred, the instrument recording curve showed normal behavior; once fluctuations appeared, the curve became irregular or made it difficult to control the system, to the point where even manual operation was ineffective. In such cases, the fault may be caused by the process control system. 6. When it is found that the displays on the DCS are abnormal, one can go to the site to check the readings of the same physical instruments; if there is a large difference between them, it is likely that there is a fault in the instrument system. In summary, when analyzing the causes of faults in field instruments, special attention should be paid to changes in the characteristics of the controlled process and control valves, as these can all be factors leading to failures in the field instrument system. Therefore, we must consider and carefully analyze both the field instrument system and the process operating system to determine the cause. 06. Precautions for starting and stopping operations: Instrument-based shutdown: This type of shutdown is relatively simple, and the precautions are as follows: 1. Work closely with process engineers ； 2. Understand the process shutdown time and the maintenance schedule for chemical equipment ； 3. Remove the instruments or sensing elements from the equipment in accordance with the maintenance schedule, to prevent damage to these instruments during maintenance; cut off the power and gas supplies before removing them. 4. Remove the instruments in a timely manner as per the maintenance plan, and when removing flanged transmitters, make sure that the tank is empty before proceeding. 5. When removing thermal resistors, transmitters, and other instruments, wrap the signal cables with insulating tape and store them properly. 6. When removing pressure gauges and pressure transmitters, be careful as the pressure tapping ports may become blocked, resulting in localized pressure buildup ； Material bursting out can cause injury; the correct procedure is to first loosen the mounting bolts, release the gas and residual liquid, and only then remove the instrument after all gas and liquid have been discharged ； 7. For electrical valve positioners, disconnect the air supply before removing them ； 8. When removing the ring chamber orifice plate, pay attention to its orientation to prevent it from being installed backwards ； 9. Clear markings should be provided when removing instruments, and they should be reinstalled in their corresponding positions to prevent confusion among instruments of the same type due to different measurement ranges, which could lead to instrument failures ； 10. For instruments with interlock control, with the consent of process personnel, switch them to manual mode to release the interlock, and then remove the instruments for maintenance. Instrument-driven operation: 1. Instrument-driven operation must be closely coordinated with the process. Depending on the process equipment, pipeline pressure testing and leak detection are carried out promptly, along with the installation of instruments, so as not to delay the start-up of the process due to these instruments ； 2. When installing instruments, be sure to pay attention to the tag numbers and match them accordingly. 3. Instrument power supply. Turn on the corresponding power switches, and check whether the 24V power voltage is normal, as well as whether the power supply for each DCS module and the UPS is functioning properly. 4. Gas source drainage. Over time, moisture and impurities accumulate in the gas supply pipeline; these amounts increase further due to start-up and shutdown operations. It must be removed before driving. Following the principle of moving from the main line to the branches, contaminants are removed step by step to prevent blockages in the constant-throttling orifice, which could otherwise cause instrument failures. 5. When installing throttling devices such as orifice plates, attention must be paid to the direction to prevent them from being installed incorrectly. Ensure that the straight sections before and after are smooth and clean, and remove any dirt promptly. The annular chamber should be located at the center of the pipeline; once the throttling device is installed, the pressure-taking valve should be opened promptly to prevent the absence of a pressure signal during startup. It is recommended to fully open the pressure tap valve using the handwheel and then turn it back half a turn. 6. When installing the control valve, ensure that the arrow on the valve body points in the same direction as the flow direction. 7. When measuring the liquid level using full-range negative migration, make sure that the negative pressure connection tube is filled with liquid. 8. For differential pressure transmitters and pressure transmitters that are protected by an isolation fluid, be sure to fill the isolation tank with this isolation fluid when restarting the equipment. 9. When wiring thermocouple compensation wires, pay attention to the positive and negative polarities to prevent incorrect connections. For thermal resistors, care must be taken not to mix up the three wires. 10. After maintenance, prior to starting up the instrument, coordinated calibration should be carried out to ensure that the readings from the field primary instruments (transmitters, sensing elements, etc.) are consistent with those of the secondary instruments in the control room (panel-mounted, rack-mounted, computer displays, etc.), or that the output values from the primary instruments match the input values from the rack-mounted instruments in the control room (distribution units, DCS input cards) ； Check that the regulator, DCS output, operator panel output, and valve position indication are consistent (or the inputs to the electrical valve positioner are consistent). The up and down strokes of the electric valve switch must be consistent. 11. For instruments with interlocks, switch them to the automatic interlock mode only after the instruments are operating properly and the process is functioning normally. So, as a qualified instrumentation professional, what are our responsibilities? Responsibilities of various instruments in the instrument control center (for reference only): I. Responsibilities of senior supervisors (senior deputy supervisors in charge of operations) 1. Take overall responsibility for the operation and maintenance of instruments in the devices located in different areas of the operation team; exercise administrative and production management powers under the leadership of the center, and complete the tasks assigned by the leadership. 2. Properly implement all the rules and regulations of the center as well as instructions from higher authorities; in addition, be responsible for addressing the mental well-being of all employees in the operation team, and develop plans for the allocation of team members as well as systems for rewards and penalties. 3. Responsible for implementing the economic responsibility system for the operation team as well as conducting assessments of various indicators, and keeping track at all times of the operating conditions of the equipment under the team’s supervision as well as any weaknesses in the production process. 4. Regularly organize operation meetings to convey instructions from higher authorities, assign tasks, and promptly analyze the status of various devices. 5. Responsible for organizing the implementation of equipment maintenance tasks in various areas; for the maintenance of large and complex equipment, it is necessary to personally oversee the work and be present on site to provide supervision and direction. 6. Keep abreast of the information related to the equipment in various areas; based on any changes in the equipment, promptly urge the relevant personnel to update the records, and submit suggestions for amending the relevant provisions in the maintenance team’s procedures. 7. Responsible for organizing technical and safety training for the personnel in the operation team, implementing plans for accident prevention measures and safety technical measures; analyzing the causes of accidents and potential hazards faced by the operation team and formulating corresponding measures, in order to adhere to the principle of not letting any accident go unaddressed. 8. Be fully responsible for the HSE work of the operation team. 9. Complete other tasks assigned by the leadership. II. Instrumentation Technical Supervisor of the Operation Team: 1. Under the direct supervision of the Operation Team leader, responsible for the technical aspects of the instrumentation operation team and bearing technical responsibilities. 2. Responsible for drafting and reviewing various procedures for the maintenance of instruments in various devices, as well as organizing technical personnel to provide training and guidance to various work teams. 3. Organize and review the urgent reports on equipment failures submitted by the work teams, analyze the causes of these failures, and promptly propose improvement or optimization solutions. And report to the supervisor of the operation team and the management staff of the center’s technical team. 4. Organize the review of the monthly maintenance plans and temporary maintenance plans submitted by the work teams; after the review is completed, the responsible party will coordinate with the maintenance team. 5. Responsible for organizing technicians to conduct timely static inspection and receipt of the delivered materials. 6. Organize the review of the submission status of the monthly reports on equipment operations. 7. Organize the review of the inventory material and spare parts replenishment plans, as well as the maintenance plans, submitted by team leaders. 8. Responsible for drafting or reviewing the technical plans for major and critical maintenance projects submitted by the organizers; after review, these plans are submitted to the management staff and supervisors at the Instrumentation Center for approval. 9. Regularly organize personnel to inspect the performance of instrument inspection and maintenance tasks by various teams, report promptly to the senior deputy supervisor of the operation team, and provide evaluation suggestions for the teams. 10. Organize instrument technicians to carry out assessments of the safe operation of instruments, and analyze existing problems and solutions. 11. In the event of malfunctions or accidents with the instruments on site, the organization should actively participate in the on-site work and provide technical support to the team members. 12. Allocate tasks reasonably based on the individual’s, host’s, and technician’s familiarity with each device. 13. Responsible for all technical tasks related to the maintenance, repair, and technical upgrading of valves in various devices. III. Responsibilities of the Shift Leader in the Operation Team 1. Under the direct supervision of the head of the operation team, responsible for the technical aspects of the instrument operation team and bearing technical responsibilities. 2. Master the performance and usage methods of various instrumentation devices, as well as the safety protection measures, and be responsible for ensuring safe production during shifts. 3. According to production needs and work plans, reasonably assign work tasks to team members, and organize the employees on duty to complete all tasks on time and to a high standard. 4. Responsible for strengthening the management and supervision of work discipline; on-duty personnel must not leave their posts without permission, must concentrate on their tasks, and must not doze off or engage in activities unrelated to their duties. 5. Be responsible for the safe operation of the instrumentation equipment during shifts; conduct inspections in accordance with the requirements of the inspection management system and keep records thereof. Perform routine maintenance on all equipment along the inspection routes within the assigned area at least once a week, and keep records of such maintenance. 6. Strengthen the inspection and management of instruments and equipment during shifts; require staff on duty to strictly follow the safety operating procedures for their positions and ensure that these procedures are implemented. 7. Be responsible for all aspects of HSE work during the shift. 8. Responsible for managing the operation records and reports of the equipment during the shift, to ensure that the records are accurate, timely, and complete. 9. Responsible for ensuring that employees on duty maintain cleanliness in their respective areas, urging them to adhere to civilized production practices, and overseeing the implementation of cleaning tasks. 10. Responsible for completing various temporary tasks that require coordination by the operations team supervisor or technicians, ensuring they are finished on time and to a high standard. Any difficulties should be reported promptly, and if completion is not possible on time, the reasons must be explained immediately. 11. Responsible for collecting suggestions from employees regarding safety production needs and the rational operation of instrumentation equipment, and conveying them promptly to the regional supervisor. 12. Conduct handover tasks strictly in accordance with the handover management regulations, and keep proper records. 13. Responsible for carrying out various on-site inspections and statistical tasks assigned by the company or center; ensure proper handover between team leaders, with the team leader on duty at that time compiling the information and submitting it to the technical management technician. 14. Be directly responsible for preparing the weekly work plan, monthly maintenance plan, and material requirement plan for the assigned area, as well as keeping records of equipment failures during shifts, managing work orders, and other related tasks. 15. Be responsible for the overall management of the shift, and attend the production meetings held by the Operations Department as required. Communicate and coordinate promptly with the process personnel in the Operations Department regarding any instrument failures that occur during shift. In the event of a parking accident, it is necessary to report it to the management of the operations team immediately, and arrange for personnel to handle the situation. After the accident has been handled, an incident report must be submitted to the technical supervisor of the operations team in accordance with the standard format required by the center. 16. Strictly implement the work order management system, and be responsible for handling work orders during the shift as well as ensuring their compliance with relevant requirements. 17. Responsible for organizing team learning and team building. 18. Complete various reports as required. 19. Responsible for attending the production meetings and equipment meetings held by the Operations Department, ensuring that the issues raised in these meetings are addressed promptly and reporting back to senior management. 20. Responsible for making changes to the interlocking settings during shifts, handling interlocking operation tickets, organizing and archiving interlocking-related documents as required, and being accountable for the entire interlocking operation process. 21. Responsible for the assessment and performance evaluation of team members. 22. Responsible for communicating and coordinating with the Operations Department regarding projects that require shutdown for maintenance within the designated area, formulating maintenance plans, and submitting them to the technical supervisor of the Operations team. 23. Accept and complete various temporary tasks assigned by the shift supervisor. 24. Be responsible for managing the warehouse during shifts and keeping proper records of goods entering and leaving the warehouse. 25. Responsible for submitting reports: (1) Submit maintenance plans and material plans on time ； (2) Submit monthly reports and weekly work plans on time ； (3) Submit weekly equipment failure statistics on time ； (4) Cooperate with the maintenance team in the regular inventory checking of materials. (5) Monthly accident record book. (6) Responsible for maintaining the ledger of leaks and losses in the assigned area, as well as tracking the resolution of such issues. (7) Responsible for maintaining the records of weekly inspections of instrument equipment in the assigned area, as well as the results of any issues resolved. (8) Submit various on-site inspection reports arranged by the center as required. (9) Maintain the ledger for the operation and maintenance of instruments in the assigned area. (10) Statistically report on the operation status of equipment in the tank farm. (11) Statistically report the operation status of safety instruments. (12) Operation status of instruments in the tank farm and flare system. IV. Responsibilities of Instrumentation Team Members (1) Check the operation status of instrumentation equipment in the plant area on a daily basis; address any issues that are detected promptly. If it is not possible to resolve them immediately, report them to the team leader and make a record, following up until the problem is resolved. (2) Carry out the repair tasks for instrumentation equipment assigned by the shift leader, as well as the tasks related to rectifying or addressing issues identified through self-inspections arranged by the team. (3) Responsible for the maintenance and repair of instruments, as well as conducting routine inspections, oiling, waste removal, calibration, and maintenance tasks at the instrument inspection and adjustment points in the area. (4) Able to operate instruments skillfully, as well as repair, calibrate, and put faulty instruments back into service. (5) Be responsible for the commissioning of new instruments for projects such as technical upgrades and hazard elimination; the commissioning must be carried out in strict accordance with the requirements specified in the drawings and instructions. (6) Keep timely records of the instruments that are repaired, including records of the repair process; these records should be as detailed as possible. (7) When using standard instruments, it is necessary to strictly follow the technical operating procedures; such instruments and meters must be submitted to the metrology department for calibration once a year. (8) Responsible for submitting monthly requests for spare parts and materials, as well as material plans. (9) Responsible for tasks such as preventing freezing, moisture damage, lightning strikes, and rain damage to instruments. (10) Under the leadership of the team leader, carry out maintenance work for the renovation and expansion of the installation.