Technical requirements for the acceptance of safety monitoring and early warning systems in flammable and explosive tank farms

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This post was last edited by hnan on 2015-12-8 at 11:38. Introduction: This standard is intended to provide technical support to the authorities responsible for safety management in carrying out safety pre-assessments and final inspections for new construction, renovation, and expansion projects. It also offers targeted comprehensive technical guidelines for the staff tasked with carrying out these tasks, ensuring that flammable and explosive storage areas constructed through such projects have an appropriate level of safety monitoring technology. This standard was proposed by the Work Safety Bureau of the Ministry of Economic Trade of the People’s Republic of China. Drafting units of this standard: Former Labor Protection Testing Technology Center, Donghua Engineering Company. Main drafters of this standard: Wang Zhimin, Xu Binghua, Lü Wuxuan, Wang Guohua, Jiao Gui. People’s Republic of China **Standard 1 Scope This standard applies to the acceptance of safety monitoring and early warning systems installed in explosive and flammable tank farms used for storing gaseous or liquid media. Where not specified in this standard, compliance with the relevant current **standard specifications shall be ensured. 2 Normative references The provisions contained in the following standards become provisions of this standard by virtue of being referenced herein. At the time of publication of this standard, the versions indicated are valid. All standards will be revised; parties using this standard should consider the possibility of using the latest versions of the following standards. GBJ74—1984 Code for Design of Petroleum Depots (including the partially revised provisions dated October 1995)
GB/T15408—1994 Power supply units for alarm systems, test methods and performance specifications
GB50058—1992 Code for Design of Electrical Installations in Explosive and Fire-Hazardous Environments
GB50160—1992 Fire protection code for the design of petrochemical enterprises
GB50166—1992 Code for construction and acceptance of automatic fire alarm systems
GB50169—1992 Code for construction and acceptance of grounding installations in electrical installation projects
GB50257—1996 Code for construction and acceptance of electrical installations in explosive and fire-hazardous environments

3 Definitions
3.1 Safety monitoring, controlling and early-warning system
A comprehensive engineering system equipped with detection and control instruments and equipment, designed to limit, control and eliminate the hazards caused by accidents; it serves to predict, forecast and warn about any unsafe conditions. 3.2 Safety early warning parameter: A physical or chemical quantity that can predict and forecast whether something is in a safe state. 4 Area division: Monitoring and early warning should be carried out in accordance with the areas specified in the relevant requirements of GB50058 and GB50160 standards. 5 Setting of safety warning parameter monitoring instruments 5.1 Ensure that the monitoring parameters are representative, and that the monitoring data is accurate and reliable. 5.2 Temperature monitoring points should be selected at representative locations. When measuring the temperature of the medium inside the tank, one or more representative temperature detection points can be set based on the tank’s capacity and the properties of the medium. 5.3 Tanks equipped with steam heaters shall be provided with appropriate facilities to control the temperature of the medium. 5.4 For pressurized storage tanks, pressure monitoring instruments shall be installed. If the medium inside the tank is a Class A material as defined in the GB50160 standard, a pressure alarm system should also be installed; where necessary, an alarm interlock system is recommended. 5.5 Liquid storage tanks must be equipped with level detection instruments; at least two different types of level detection instruments shall be installed on the same tank. Storage tanks holding flammable and explosive materials should be equipped with high and low liquid level alarm circuits; where necessary, they should also have an interlock system linking the liquid level to relevant process parameters. 5.6 Equip gas detectors with appropriate performance based on the different properties of the media stored in the tank area. In areas where flammable gases are present, flammable gas detectors must be used ； In areas where high temperatures and radiation may cause fires, temperature detectors, smoke detectors, or flame detectors, or a combination of these, should be installed. 5.7 When installing combustible gas detectors and fire alarms in the tank area and its pump rooms, factors such as the properties of the combustible gases, the location of leakage points, the overall layout, air flow in the surrounding area, and the building structure should be taken into comprehensive consideration. The distance between two combustible gas detection probes must not exceed 20 m. Intrinsically important areas should be equipped with separate inhalable combustible gas detectors. 5.8 Gas detectors should be installed preferentially on the downstream side of the prevailing wind direction at the medium leakage point. 5.9 Control rooms or automatic analyzer rooms located within the tank area shall be equipped with combustible gas detectors or smoke detectors, as well as audible and visual alarm systems. 6 Guidelines for hardware configuration of safety monitoring and early warning systems. 6.1 The setup of the system can be divided into three levels: local safety monitoring and early warning system ； Control room safety monitoring and early warning system ； Security monitoring and early warning system for the central dispatch control center. 6.2 On-site safety monitoring and early warning system 6.2.1 It shall be capable of transmitting safety early warning parameters to the control room and/or central dispatching control center. 6.2.2 It shall be located at a position where it can be easily observed by operators. 6.2.3 The audible and visual alarm signals emitted shall be clearly distinguishable from background noises and lights. 6.2.4 Each measuring instrument for safety monitoring and early warning parameters shall be labeled with a name. 6.2.5 At least one manual accident alarm button shall be installed in each monitoring and early warning area. If the area is large, more than two manual accident alarm buttons can be installed as needed. The manual accident alarm button should be located in a visible and easily accessible position, and should be clearly marked. 6.3 Safety monitoring and early warning system for control rooms
6.3.1 Necessary facilities shall be provided to collect, display, record, store, and process real-time detection results of safety early warning parameters; to predict and forecast the safety status, make judgments, and issue instructions accordingly. The results shall be transmitted to the central dispatch and control center. 6.3.2 The emitted audible and visual signals or voice alarms shall be clearly distinguishable from the alarm signals for process operating parameters. 6.3.3 Communication facilities such as walkie-talkies or intercoms should be provided with the central dispatch control center or fire station. 6.3.4 Disaster and accident broadcasting facilities shall be provided to enable the emergency deployment of personnel and resources. 6.3.5 An accident alarm button shall be installed; this button should be placed in a suitable location, equipped with a protective cover and clear markings. 6.4 Safety monitoring and early warning system for the Central Dispatch and Control Center ； 6.4.1 Necessary facilities should be provided to receive safety monitoring warning signals from the field and control rooms, as well as to have functions for display, recording, storage, and processing; these facilities should also be capable of predicting, forecasting, and assessing the safety status, and issuing corresponding commands. 6.4.2 Equipped with communication facilities between the control room and the fire station. 6.4.3 There is a disaster notification and communication system with the local fire department. 6.4.4 A plant-wide disaster accident broadcasting system is installed. 6.5 The aforementioned three-level monitoring and early warning system shall also meet the following requirements: 6.5.1 The reliability of the safety monitoring and early warning facilities must comply with relevant standard requirements. 6.5.2 The safety monitoring and early warning signal circuits shall be configured separately from the alarm circuits for normal process parameter signals, and a redundant hot standby system shall be employed. The early warning signal circuit should have a spare capacity of 10% to 20%. 6.5.3 In the event of a malfunction in either the optical alarm signal system or the audible alarm system of the safety monitoring and early warning system, they shall not affect each other. 6.5.4 The interlock alarm circuit of the safety monitoring and early warning system shall be equipped with checking and resetting devices, and shall have identification and memory functions when necessary. 6.5.5 Instruments, meters, and electrical equipment used in explosive hazard areas within tank farms must comply with the relevant regulations regarding explosion-proof performance classification. All products must be inspected and certified as qualified by an explosion-proof product quality supervision and inspection agency recognized by **relevant authorities**. 6.6 Power Safety Monitoring and Early Warning System: The power safety monitoring and early warning system shall be equipped with a main power supply, a DC backup power supply, and an automatic switching device. The main power supply should be a reliable power source. A DC backup power supply should be an independent power supply system composed of dedicated batteries, or a UPS uninterruptible power supply device. The voltage of the DC backup power supply should be 24V, and its capacity should be sufficient to provide power for at least 30 minutes. 7 Cable Laying 7.1 The cable laying for the safety monitoring and early warning system shall be carried out in accordance with the relevant provisions of GB50257. 7.2 General Provisions 7.2.1 Rubber/plastic-sheathed cables or intrinsically safe cables shall be selected according to the category and level of explosive hazard areas, as well as the rated voltage and current ratings of the explosion-proof electrical equipment. Signal transmission lines should use insulated wires with copper cores or copper cables; furthermore, cables with heat resistance, low-temperature resistance, flame-retardant insulation properties, and corrosion resistance should be selected depending on the operating environment. 7.2.2 When wires and cables are installed exposed, they should be protected using steel pipes or cable trays. When laid in a cable trench, it shall be laid separately from power transmission cables, maintaining the specified distance. If a steel-banded armored cable is used for underground installation, no protective measures may be necessary in locations where it is not prone to mechanical damage, but the relevant regulations for underground cable installation must still be followed. 7.2.3 When using multi-core cables, spare conductors shall be provided, and the number of such spare conductors shall be no less than 15% to 20% of the number of working conductors. 7.3 Intrinsically Safe Circuits 7.3.1 For circuit wiring, twisted pair signal transmission wires/cables are typically used; it is necessary to avoid any contact with non-intrinsically safe circuits in order to prevent static induction or electromagnetic induction caused by such circuits. 7.3.2 Cables, steel pipes, and terminal boards in circuit wiring shall have blue markings. When two or more intrinsically safe circuits share a terminal block, the wire ends should be marked with circuit numbers for identification. 7.3.3 During circuit acceptance, it is necessary to verify that all components, connectors, and cables in the circuit possess intrinsic safety certificates; no non-intrinsically safe devices shall be present among them. 7.4 Grounding protection facilities
7.4.1 The tank farm shall be equipped with a grounding protection system to prevent lightning and static electricity. 7.4.2 The grounding electrode for operational grounding shall be located near the control room; there shall be two or more connection points between the grounding main line and the grounding electrode, and the operational grounding resistance shall be less than or equal to 4Ω. 7.4.3 The metal sheath or shielding layer of cables entering explosive hazard areas shall be grounded at the control room end; grounding is permitted only at one end. The grounding electrode shall be installed in a non-explosive hazard area. 7.4.4 In principle, intrinsically safe circuits shall not be grounded; in cases where special requirements exist, their grounding system and grounding resistance values must comply with the relevant specifications outlined in the product manual or design guidelines. 8 Acceptance of the safety monitoring and early warning system 8.1 General provisions 8.1.1 The safety monitoring and early warning system for areas containing flammable and explosive materials shall be accepted simultaneously with the main construction work. 8.1.2 The acceptance shall be carried out under the supervision of the competent department for work safety, presided over by the unit in charge of the construction project, and jointly conducted by professionals from relevant units such as those responsible for design and construction. 8.2 Application for acceptance: Before the application system is accepted, the project owner shall submit an acceptance application report to the competent department in charge of work safety, along with the following technical documents: 8.2.1 Information on the types and properties of hazardous materials, the classification of their explosion hazards, as well as details related to the project. 8.2.2 Design approval documents, system as-built drawings, and system as-built sheet (including a list of monitoring and control points). 8.2.3 Construction records (including records of acceptance for concealed works), commissioning reports. 8.2.4 Registration forms for maintenance and management systems, organizational structure, and staffing. 8.2.5 Technical documents such as product manuals and certificates of conformity provided by the manufacturer. 8.3 Approval of acceptance applications
8.3.1 The department responsible for work safety is in charge of reviewing the technical documents submitted by the applicants for acceptance. The key aspects of this review are as follows:
8.3.1.1 Classification of zones with explosion hazards. 8.3.1.2 Safety monitoring and early warning measures taken (including the composition of system software). 8.3.1.3 Selection and configuration of instruments, electrical equipment, and materials. 8.3.1.4 Whether other documents and materials meet the specifications of the safety monitoring and early warning system. 8.3.2 After the competent department for work safety approves the application report for acceptance, it shall designate a specialized agency to organize and carry out the implementation. 8.4 Implementation of acceptance 8.4.1 The acceptance of the safety monitoring and early warning system shall be carried out in accordance with the requirements of this standard, and with reference to the relevant provisions on \"Project handover and acceptance\" in Section 6 of GB50257—1996. 8.4.2 For power supply inspection, in accordance with GB/T15408, the automatic switching device of the uninterruptible power supply shall be subjected to three switching tests, and each switch should operate properly. 8.4.3 Functional sampling tests for detectors in the safety monitoring and early warning system shall be carried out on detectors in accordance with the following requirements: 8.4.3.1 When the actual number of installed detectors is 10 or less, five of them shall be sampled for testing. 8.4.3.2 When the actual number of installations is 10 or more, a sample inspection shall be conducted at a rate of 30% to 50% of the total number, with the total number of units inspected being no less than five. 8.4.3.3 In case of any detectors found to be non-compliant in terms of functionality, double the number shall be randomly sampled for inspection; all additionally sampled detectors must also be functioning properly. 8.4.4 Acceptance inspection of the grounding system: The grounding resistance of the lightning protection, anti-static, protective and working grounding systems, as well as the intrinsically safe grounding system, and these systems themselves must comply with the relevant specifications. 8.4.5 Sampling Inspection of Interlock Alarm Functions 8.4.5.1 The functional performance of the test, confirmation, mute, and reset buttons used in the interlock alarm system, as well as the local alarm buttons and the interlock release switches, shall all be satisfactory. 8.4.5.2 If the number of alarm points is below 100, 5 to 10 alarm circuits are sampled; if the number of alarm points is above 101, sampling is carried out at a rate of 5% to 10%, and all sampled circuits must be qualified; otherwise, the sampling volume should be doubled. 8.4.6 Acceptance of communication and broadcasting systems 8.4.6.1 The communication equipment in each control room and fire station, or central dispatch control center, shall be in proper working condition. 8.4.6.2 The telephones in the control room or central dispatch control center should function normally when tested for communication with the “119 Service”. 8.4.6.3 Broadcast tests shall be conducted at the positions where the broadcast system is installed, and the speakers and amplifiers must function properly. 8.4.7 Acceptance of system software 8.4.7.1 The repeatability of interlocking operations should generally be checked three times; if accurate, it is considered qualified. 8.4.7.2 Simulate signals of safety warning parameters for input, operate the system, and observe whether the monitoring and warning functions achieve the intended objectives. 8.4.7.3 The safety monitoring and early warning system software shall have a self-diagnosis function. 8.4.8 Safety management systems and verification of personnel qualifications 8.4.8.1 Safety management systems should include: operating procedures, a system for registering safety hazards, a responsibility system for safe production, a system for regular inspection and maintenance of equipment and instruments, as well as safety education and training programs for personnel. 8.4.8.2 Inspection and verification of safety management and the qualifications of duty personnel: The persons in charge of the safety monitoring and early warning system, as well as the duty personnel, must have a thorough understanding of all aspects of the safety early warning and monitoring system as well as its operation and maintenance requirements. They must receive training on safety management knowledge and hold valid certification for such training ； One must pass the training assessment before being allowed to take up the position. During acceptance, the knowledge and skills that relevant personnel should possess can be assessed; those who fail the assessment will have their eligibility to work revoked. 8.5 Signing and issuance of the certificate of acceptance: After all the aforementioned acceptance tasks are completed, the inspection personnel submit their opinions on acceptance; thereafter, the department responsible for work safety, along with the construction, design, and installation units, jointly sign the certificate of acceptance, in four copies. Issued after stamping.