Inspection and maintenance of explosion-proof electrical installations
1. Terms and Definitions
General examination
This includes visual inspections as well as inspections using proximity equipment such as ladders (where necessary) and tools to identify obvious defects, such as loose bolts.
Continuous supervision
Regular maintenance, inspection, management, monitoring and maintenance of electrical installations are carried out by professionals experienced in professional installation and use environments in order to maintain the explosion-proof performance of the installations in good condition.
Check in detail
This includes general inspections as well as inspections in which obvious defects, such as loose terminals, can only be identified by opening the housing and/or (if necessary) using tools and inspection equipment.
Hazardous locations
Areas where explosive atmospheres are or are expected to occur in such large quantities that special measures are required for the construction, installation and use of electrical equipment.
Initial checks
Inspection of all electrical equipment systems and installations prior to commissioning.
examine
In order to obtain the conclusion that the equipment is safe and reliable, the equipment is not disassembled or partially disassembled as needed, supplemented by some test measures.
maintenance
Comprehensive activities to maintain or restore products to a state that meets the requirements of the relevant technical specifications and to achieve their required functions.
Non-hazardous locations
Areas where explosive atmospheres are not expected to occur in large quantities and do not require special measures for the construction, installation and use of electrical equipment.
Regular check-ups
Routine inspection of all electrical equipment, systems and installations.
Spot checks
Inspections of certain electrical equipment, systems and installations
Professionals
Personnel who have undergone operational training, including various explosion-proof types, installation practices, the requirements of this section, relevant national regulations and corporate regulations applicable to installation, and general principles of hazardous location classification.
Technicians with administrative functions
Professionals who perform technical management, have sufficient knowledge of the field of explosion protection, are familiar with local conditions, are familiar with installation, and have full responsibility and management functions for the inspection system of electrical equipment for hazardous locations.
Visual inspection
Inspections that use the naked eye without approaching equipment or tools to identify obvious defects, such as missing bolts, etc.
2. General requirements
1. Documents
For inspection and maintenance, the following up-to-date documents should be provided
a) Hazardous location classification and equipment protection level (EPL) required by the site (see GB 3836.14 and GB12476.3);
b) Gases: equipment category (II.A, II.B, and II.C) and temperature group requirements;
c) Dust: Equipment category (III.A, III.B, and III.C) and maximum surface temperature requirements
d) Equipment characteristics, e.g. temperature range, explosion-proof type enclosure protection class (IP code), corrosion resistance;
e) Records that enable the explosion-proof equipment to be maintained to conform to its explosion-proof type (see GB3836.15) (e.g. equipment list and equipment location, spare parts, certificate of conformity and technical information):
f) Documents not covered by the photocopies of previous inspection records may be in accordance with the requirements of GB 3836.15 or GB 3836.13.
2. Personnel qualifications
Experienced and trained qualificationsTraining content: including various explosion-proof types, installation practices, requirements of this section, installation-related national regulations/corporate regulations, and general principles of hazardous location classification, etc.: Receive regular continuing education or training.
3. Check
An initial inspection of the entire plant or equipment should be carried out before they are put into operation. In order to ensure that the electrical installation is in good condition and can be used in hazardous locations for a long time, the following two inspections should be carried out
a) Periodic inspections;
b) Continuously supervised by professionals and, if necessary, maintained.
Any subsequent adjustments, maintenance, repairs, restorations, modifications or replacement of equipment and associated equipment components shall be subject to a detailed inspection.
When a nameplate or marking on an explosion-proof device is missing or illegible, a common alternative is to establish an explosion-proof certificate of conformity traceable to the equipment. The following methods can be used: attach an identification tag containing a unique tag number, a serial number, or an installation-related file. Methods of attaching or fixing signage should not detract from the integrity of the equipment.
The equipment dossiers and identification marking methods used to manage explosion-proof equipment should be able to track the replacement or repair status of the equipment, which may have different certification marks and specific requirements than the original equipment
If, at any time, there is a change in the classification of hazardous locations, a change in the required level of protection (EPL) of equipment, or a change in the location of electrical equipment, an inspection should be carried out to ensure that the appropriate type of explosion protection and surface temperature are appropriate to the conditions that have been altered. If the unit or equipment needs to be disassembled during inspection, measures should be taken to ensure that the integrity of the explosion-proof type is not compromised when reassembled, including removal of residual dust and replacement of gaskets.
3.1 Check the grade
The inspection level is classified as a visual inspection, a general inspection, or a detailed inspection.
Visual inspections and general inspections can be performed while the equipment is live, and detailed inspections generally require the equipment to be de-energized.
3.2 Types of Inspections
The initial inspection is used to check the suitability of the selected explosion-proof type to its installation requirements, based on a detailed inspection.
Periodic inspections can be visual or general inspections and may require further detailed examinations. Sampling inspections can be visual, general, or detailed. The specification and structure of the sample should be determined according to the purpose of the inspection.
3. Regular inspections
1. Personnel
Routine periodic inspections require personnel
a) Knowledge of Site Classification/Equipment Protection Level (EPL) and knowledge sufficient to technically judge the actual situation on site;
b) Knowledge of the theoretical and practical requirements of electrical equipment for hazardous locations from a technical point of view;
c) Understand the requirements for visual inspection, general inspection and detailed inspection in relation to the installed equipment and installations.
These personnel should be given sufficient independence to carry out, for example, maintenance activities, so as not to interfere with the reliability of the results of the inspections they report.
2, Stationary device
Accurately predicting the right interval for periodic check-ups is a complex task. The determination of the inspection level and the interval between periodic inspections should take into account the type of equipment, the manufacturer's instructions, factors affecting the degree of damage, the classification of the site and/or the requirements of the Equipment Protection Level (EPL) and the results of previous inspections. When inspection levels and time intervals have been established for similar equipment installations and environments, these experiences should be used to determine the inspection protocol.
In general, the interval between regular inspections should not exceed 3 years.
Once the inspection interval is fixed, a temporary sampling inspection of the unit should be carried out in order to verify that the proposed interval needs to be modified. Again, the inspection level needs to be determined, and the sampling check can be used again to verify that the proposed time interval needs to be modified. It is necessary to conduct a prescribed review of the inspection results to adjust the inspection interval and inspection level.
3. Mobile equipment
Mobile electrical equipment (portable, portable and mobile) is particularly susceptible to damage or misuse, so the interval between periodic inspections can be shortened according to actual needs. General inspections should be carried out at least every 12 months for mobile electrical equipment, and detailed inspections should be carried out at least every 6 months for frequently opened enclosures (e.g. battery covers). In addition, such equipment is visually inspected by the user before use to ensure that there is no visible damage to the equipment.