Requirements for the metrological performance of vertical metal tanks as specified in JJG168-2005 calibration regulations
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1. Requirements for the expanded uncertainty of calibration results: For vertical metal tanks with a capacity of 20 m3 to 100 m3 (including 100 m3), the expanded uncertainty of the total capacity after calibration shall be 0.3% (k=2)； Vertical metal tanks with a capacity of 100 m3 to 700 m3 (including 700 m3), for which the expanded uncertainty of the total capacity after calibration is 0.2% (k=2) ； For vertical metal tanks with a capacity of 700 m3 or more, the expanded uncertainty of the total capacity after calibration is 0.1% (k=2). 2. Ellipticity requirement for the tank body: The ellipticity of the tank body in newly constructed tanks must not exceed 1%. 3. Tilt requirement for the tank: The tilt of the tank must not exceed 1°.
The inclination of the tank body shall not exceed 1°, and the ellipticity of the tank body in newly built tanks shall not exceed 1%. This is the exact wording from JJG168-2005
1. Tank construction requirements: The tank shall be constructed in accordance with the proper engineering specifications and must meet the relevant safety requirements for oil tanks； A permanent nameplate shall be installed in a prominent position on the tank, indicating the tank’s name, specifications and model, equipment number, manufacturer, date of construction, etc ； The tank shall have sufficient strength; under normal conditions, it shall not suffer any permanent deformation that affects its capacity ； For floating roof tanks, it is necessary to ensure that the floating roof can move freely up and down with the liquid level. 2. Reference height requirement: Regardless of changes in the liquid contained in the tank or in temperature, the reference height is allowed to change only slightly, and such changes have an impact on the measurement uncertainty that can be ignored. 3. Requirements for the gauge groove below the measuring port: The measuring port of the tank must have a gauge groove to determine the position for measuring the height. 4. Requirements for the gauge plate: The tank must be equipped with a gauge plate, with the lower gauge reference point located on this plate. 5. Requirements for the stability of the tank bottom plate: The foundation of the tank must be stable, and there must be no gaps between the tank foundation and the tank bottom plate that could affect measurement accuracy. 6. Requirements for the measurement position of the base circle diameter: The measurement position for the base circle diameter is 100 mm above and below 3/4 of the outer height or inner height of the first ring plate. No obstacles are allowed in its position.
Promote the inspection regulations for vertical metal tanks to those involved in storage and transportation; only one aspect can be discussed at a time.