Safety Management System for Explosion-Proof Electrical Equipment and Instrumentation

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1. Purpose: This regulation is established to prevent fire or explosion accidents caused by electric sparks or hazardous temperatures generated from explosion-proof electrical equipment and wiring in areas of the facility where there is an explosion risk. Appropriate safety technologies and management measures are implemented to ensure the safety of company employees and property. 2. This scope applies to the design, installation, safety and technical management, inspection and testing, as well as maintenance of all explosion-proof electrical equipment within the company’s plant area. 3. Classification of areas with gas explosion hazards: Areas where explosive gases or flammable vapors mix with air to form explosive mixtures are classified into three zone categories based on their degree of hazard. 3.1 Class 0 area: A place where, under normal conditions, explosive gas mixtures occur continuously, frequently for short periods of time, or persist for long periods. 3.2 Class 1 areas: Places where explosive gas mixtures may occur under normal conditions. 3.3 Class 2 areas: Places where, under normal conditions, explosive gas mixtures cannot occur, and only appear occasionally for short periods under abnormal conditions. 4. General safety regulations for explosion-proof electrical equipment 4.1 Explosion-proof electrical equipment used in areas with explosion hazards must, during operation, possess the capability of not igniting the explosive mixtures present in the surrounding area. 4.2 Explosion-proof electrical equipment used in explosive hazard areas must pass inspection by a qualified testing agency before it can be put into use. 4.3 Electrical equipment of various explosion-proof types shall be equipped with nameplates indicating the explosion-proof inspection certificate number as well as the type and grade of explosion protection; permanent marks indicating the explosion-proof inspection status and the type and grade of explosion protection shall be provided in a prominent location on the equipment. 4.4 The classification, grading, and grouping of explosion-proof electrical equipment follow the same methods as those for the classification, grading, and grouping of explosive substances; their grade parameters and symbols are also identical. 4.5 The maximum surface temperature of explosion-proof electrical equipment shall meet the requirements of the specifications; under normal operating conditions, it shall not generate any sparks or reach dangerous temperatures capable of igniting explosive mixtures. 4.6 The selection of explosion-proof electrical equipment shall comply with the requirements of “Explosion-Proof Electrical Equipment for Use in Explosive Atmospheres” and “Electrical Safety Regulations for Explosive Hazardous Areas”. 4.7 Electrical wiring in areas with explosion hazards should be installed in areas where the risk of explosion is lower or at locations farther away from the source of release. It should be kept away from places prone to mechanical damage, vibration, corrosion, dust accumulation, and hazardous temperatures. When the requirements cannot be met, appropriate protective measures should be taken to satisfy the safety requirements of these locations. 5. Operation and Maintenance of Explosion-Proof Electrical Equipment
5.1 General safety regulations
(1) Explosion-proof electrical equipment shall be operated, used, and maintained by personnel who have been trained and certified by the relevant safety inspection authorities. (2) Explosion-proof electrical equipment shall be operated under the operating technical conditions specified by the manufacturer. (3) Protective, locking, monitoring, indicating devices, etc., on equipment shall not be removed at will; they must be kept intact, sensitive, and reliable. When maintaining and inspecting equipment in locations with explosion hazards, it is strictly prohibited to disable protective, interlock, and signaling devices ； (4) Forced power restoration is prohibited before the cause of a fault-induced outage is identified ； It is strictly prohibited to connect wires while they are still energized (using an open flame for connection) and to use tools or equipment that can generate sparks. To clean the interior of equipment containing flammable and explosive materials, the power supply must be turned off, and a warning sign must be placed ； Before supplying power to equipment containing flammable and explosive substances, it is necessary to measure the concentration of explosive mixtures both inside and in the surrounding environment; power may be supplied only after safety has been confirmed. (5) New equipment should be disassembled for inspection before installation, and can be put into operation only after meeting the specified requirements. 5.2 The operation and maintenance inspections for explosion-proof electrical equipment are divided into three types: daily operation and maintenance inspections, specialized maintenance inspections, and safety and technical inspections. (1) Routine operation and maintenance inspections: The enclosures of explosion-proof electrical equipment must be kept clean, along with their surrounding environment. Any debris or flammable materials that could impede the safe operation of the equipment should be removed. Designated personnel should regularly measure the concentration of explosive mixtures in the vicinity of the equipment. When in operation, the equipment should have good ventilation and heat dissipation conditions. Check that the surface temperature of the enclosure does not exceed the maximum temperature and temperature rise limits specified for the product. During operation, the equipment should not be damaged by external forces, and there should be no tilting or component friction. The sound should be normal, and the vibration values must not exceed the specified limits. For motors in operation, the bearing areas should be inspected; they must be kept clean and supplied with the specified amount of oil. The surface temperature of the bearings should also be checked to ensure it does not exceed the specified limit. Check that all fixing bolts and spring washers at various parts of the housing are present and tightened; they must not be loose. The enclosure of the equipment should be free from cracks and any mechanical deformations that could compromise its explosion-proof properties. The cable entry device should be reliably sealed. Unused wire holes shall be sealed with steel plates or plug washers having a thickness of not less than 2 millimeters. The device is equipped with complete and proper protection, interlock, monitoring, alarm, grounding, and other devices. Check whether the explosion-proof lighting fixtures maintain the integrity of their explosion-proof structure and protective covers as required. The surface temperature of the lighting fixture must not exceed the value specified by the product. In areas with explosion hazards, except for motors whose specifications permit frequent starting, no other type of explosion-proof motor is allowed to be started frequently. When an abnormal situation occurs during the operation of electrical equipment, the operator can take emergency measures to shut down the equipment and notify professional maintenance personnel to conduct inspections and repairs. The personnel responsible for operating the equipment should handle any abnormalities identified during routine operation, maintenance, and inspections as soon as possible. If they are unable to deal with such issues, they should inform the electrical maintenance staff to take care of them. All problems or accidents that occur must be recorded in the equipment operation logs. (2) Professional maintenance checks: Replacing lighting bulbs, fuses, and the power batteries of intrinsically safe devices must all comply with the specifications specified in the design; no changes should be made arbitrarily. Clean the internal and external dust from the control equipment, and carry out rust removal and anti-corrosion treatment. Check the condition of the equipment and electrical wiring. Check the reliability of the grounding wire as well as the condition of cables, junction boxes, etc. During a power outage, check whether the internal moving parts of the electrical appliance show wear beyond the specified limits, and whether the wiring terminals are secure and reliable. Check the explosion-proof structural parameters of various types of explosion-proof electrical equipment, as well as the parameters of intrinsically safe circuits. Verify whether control devices, measuring instruments, telecommunications equipment, and protective devices meet the explosion-proof safety requirements, and whether they are in good condition, sensitive, reliable, and free from any other defects. Examine the issues noted in the equipment operation records or defect records; any issues that can be resolved promptly should be addressed to eliminate potential hazards. Any issues that cannot be handled should be reported promptly. 6. Maintenance of explosion-proof electrical equipment 6.1 General safety regulations The maintenance of explosion-proof electrical equipment should be carried out by designated professional repair units.  Personnel responsible for the maintenance and inspection of explosion-proof electrical equipment should receive training in the skills required for repairing such equipment; only those who pass the relevant assessments may undertake maintenance and inspection tasks.  After the maintenance of explosion-proof electrical equipment, the maintenance personnel fill out a maintenance record, which must then be inspected by qualified professionals specializing in explosion-proof safety. Only after a certificate of compliance is issued can the equipment be put into use.  In areas with explosion hazards, it is prohibited to perform maintenance on electrical equipment and circuits while they are energized (except for intrinsically safe circuits), as well as to schedule power outages or restorations. A warning sign reading “Work in progress, do not close the switch” should also be placed at the power-off point. The maintenance of flameproof enclosures shall be carried out in accordance with **current technical regulations. During maintenance, no modifications or replacements shall be made to the shell structure, nor to the materials and dimensions of the main components. When modification or replacement is necessary, changes must be made only with the consent of the original testing and certification agency for that product, while ensuring the equipment’s original safety performance. When performing maintenance on explosion-proof electrical equipment and circuits in areas with explosion hazards, it is necessary to obtain approval for carrying out such work. 6.2 Minor repairs: In addition to the routine operational maintenance and electrical inspection tasks mentioned above, minor repairs should also include the following key tasks: removing dust and dirt from inside and outside the equipment casing ；  Replace or repair worn-out components and fasteners ；  Repair or adjust the operating mechanisms and locking devices of the equipment ；  Clean the flameproof surface, remove rust, apply a thin layer of anti-rust grease, and check the condition of the flameproof surface ；  Measure the gap of the flameproof surface and check the condition of the enclosure; test the insulation resistance and inspect the electrical system ； Repair or replace individual components of the electrical system ； Oil samples are taken from the oil filling equipment for chemical analysis and electrical insulation strength testing ； Check all wiring connections of the equipment for looseness and other defects, and carry out repairs. 6.3 Medium repair: In addition to the minor repair tasks, medium repair should also include the following main tasks: disassembly and inspection of the equipment, thorough cleaning ； Addressing the local deformation of the housing caused by external force damage ； Thoroughly inspect the electrical and mechanical structures; repair or replace their components ； Repair the flameproof surface, remove rust, and measure the flameproof gap ； Strengthen and treat the winding insulation of motors and transformers ； Change the internal wiring of motors and transformers as needed ； Verification and adjustment of the setting values of relay protection devices and the accuracy of instruments ； Conduct insulation performance tests on electrical equipment as specified ； The inner walls of the shell cavity are coated with arc-resistant paint, while the outer surface of the shell is coated with anti-rust paint. 6.4 Major Overhaul: In addition to the routine maintenance tasks, a major overhaul should also include the following key activities: replacement and repair of the explosion-proof components of the enclosure, as well as conducting necessary hydrostatic tests ； Perform repairs such as fitting sleeves for the motor end cover rabbets, replacing the end cover, fitting sleeves for the rotor shaft, and welding repairs ； Replace the base plate, core frame, and wiring of the magnetic starter or feeder switch ； Rewinding the windings of motors and transformers ； Adjust the characteristics of various relay protection devices in tests ； Conduct insulation strength tests and inspections of electrical equipment and wiring as required, as well as adjustment tests of control and protection devices ； Replace cable lines and steel pipe wiring in a localized area ； Update the fixing components for cable lines and steel pipe wiring, and remove rust from the exterior surface and apply paint. 7. Establish equipment records. The company shall establish records for explosion-proof electrical equipment. From equipment installation, commissioning, operation, maintenance, defect handling, accident repair, and modernization/retrofitting, to the explosion-proof downgrading and scrapping of the equipment, all kinds of technical data from various stages should be comprehensively collected, organized, and archived for easy reference.