【Standard Text】GB 50074-2014 Code for Design of Oil Depots (Automatic Control Section)

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This post was last edited by auto360 on 2016-3-2 at 08:38. The following is an excerpt from the GB 50074-2014 Code for Design of Oil Depots; it is in electronic format, making it easier to carry and consult. Specifications related to various automatic control instruments are updated from time to time. 15 Automatic Control and Telecommunications 15.1 Automatic Control Systems and Instruments 15.1.1 Tanks with a capacity of more than 100 m3 shall be equipped with remote liquid level measurement instruments, and the following requirements shall be met: 1 The continuous liquid level measurement signals shall be transmitted to the automatic control system in either analog form or via communication methods. 2 High and low liquid level alarms should be installed in the automatic control system. 3 The set height for the high liquid level alarm in storage tanks shall comply with the relevant provisions of the current industry standard \"Design Code for Tank Areas in Petrochemical Storage and Transportation Systems\" SH/T 3007. 4 The set level for the low liquid level alarm in storage tanks should be such that cavitation does not occur in the pumps. For external floating roof and internal floating roof storage tanks, the set level for the low liquid level alarm (measured from the bottom of the tank) should be at least 0.2m above the height at which the floating roof touches the bottom of the tank. 15.1.2 The following storage tanks shall be equipped with high liquid level alarms and interlocks; the high liquid level alarm shall be capable of interlocking to close the control valve of the tank’s inlet pipeline simultaneously ； Class A B liquid storage tanks with a turnover rate of more than 6 times per year and a capacity of 10,000 m3 or more ； Class A B and Class B liquid storage tanks with a turnover rate of 6 times or less over 2 years, and a capacity of more than 20,000 m3 ； 3 Storage tanks for liquids of toxicity grades I and II. 15.1.3 External floating roof tanks and internal floating roof tanks with a capacity of 50,000 m3 or more shall be equipped with a low-low liquid level alarm. The set height for the low-low liquid level alarm (measured from the bottom of the tank) should not be lower than the height at which the floating roof touches the bottom; the low-low liquid level alarm should also be capable of triggering the pump to stop simultaneously. 15.1.4 The level measuring instruments used for high and low high/low level alarm signals in storage tanks shall be separate continuous level measuring instruments or level switches, and alarms and interlocks shall be provided in the automatic control system. 15.1.5 Storage tanks whose storage temperature needs to be controlled and monitored shall be equipped with temperature measuring instruments, and the temperature measurement signals shall be transmitted remotely to the control room. 15.1.6 For external floating roof storage tanks with a capacity of 50,000 m3 or more, their foam fire extinguishing systems shall employ an automatic control method that requires manual confirmation. 15.1.7 For the key processes in Class I oil depots, as well as electric equipment such as pumps, fire pumps, and tank agitators, and control valves, it is required that they can not only be operated on-site but also be controlled from the control room, with their status displayed there. For the important processes in headphone oil depots, electric equipment such as pumps, fire pumps, tank agitators, and control valves should not only be operable on-site but also enable control and status monitoring from the control room. 15.1.8 Pressure measuring instruments shall still be installed on the outlet pipelines of combustible liquid transfer pumps; these instruments should be capable of displaying readings locally. In primary oil depots, the pressure measurement signals shall also be transmitted to the control room. 15.1.9 The installation of toxic gas and flammable gas detectors shall comply with the following provisions: 1 Detectors for toxic gases shall be installed in areas where leaks of toxic gases may occur, such as pump stations for toxic liquids, loading/unloading stations, metering stations, areas where valves are located on storage tanks, and drainage wells. 2 In rooms equipped with Class A flammable liquid equipment, such as Type A, automatic detection and alarm devices for combustible gas concentrations should be installed. 3 In open areas of Class A and Class B A liquids in primary oil depots, such as pump stations, loading/unloading stations, metering stations, locations where valves are concentrated on above-ground storage tanks, and drainage wells, where flammable gases may leak or accumulate, flammable gas detectors should be installed ； Portable combustible gas detectors can be installed in the stairwells of the attached tank complex and gas-grade oil depots. 4 The design of the combustible gas and toxic gas detection and alarm systems for Class I oil depots shall comply with the relevant provisions of the current standard **\"Design Code for Detection and Alarm of Combustible Gas and Toxic Gas in Petrochemical Industries\" GB 50493. 15.1.10 For monitoring and sequential control operations related to fire protection in Class 1 oil depots, one of the following two methods shall be adopted: 1 Use a dedicated monitoring system that communicates with the depot’s automatic control system via a communication interface ； 2 Install separate I/O cards and a separate display operation station in the automatic control system of the oil depot. 15.1.11 The start and stop of the fire pumps in Class I oil depots, as well as the opening and closing of the control valves on the fire water pipelines and foam liquid pipelines, shall all be capable of being controlled remotely from the fire control room. The main control panel shall display the operating status of the pumps and the valve position signals of the control valves. 15.1.12 The instrumentation and computer monitoring management system shall be powered by a UPS uninterruptible power supply; the backup battery pack of the UPS shall provide at least 30 minutes of AC power supply time after the external power source is disconnected. 15.1.13 The outdoor cable laying for automatic control systems shall comply with the following provisions: 1 Instrument cables laid in the production area should preferably be installed underground using methods such as cable trenches, cable protection pipes, or direct burial. When a cable trench is used, it should be filled tightly with sand. 2 For cables that truly need to be laid on the ground in certain areas of the production site, they should be installed using galvanized steel protective tubes or fully enclosed metal cable trays with covers.