API MPMS 4.4:1998(R2010) pdf download.Manual of Petroleum Measurement Standards Chapter 4—Proving Systems
4 Equipment
4.1 GENERAL CONSIDERATIONS All components of the tank prover installation, including connecting piping, valves, and manifolds, shall be in accor- dance with applicable pressure codes. Once a closed tank prover is on stream, it becomes part of the pressure system. Provisions should be made for expansion and contraction, vibration, reaction to pressure surges, and other process conditions. Consideration should be given to the installation of valving to isolate the tank prover from line pressure when the system is not in use or during maintenance. All closed tank provers should be equipped with vent and drain connections. Provisions should be made for the disposal of liquids and/or vapors that are drained or vented from the tank prover. The dis- posal may be accomplished by pumping liquids or vapors back into the system or by diverting them to a collecting point. Blind flanges or valve connections should be provided on either side of a double block-and-bleed valve in the tank prover piping system. These connections can serve as loca- tions for proving portable meters or as a means of calibrating the tank prover by the master-meter or waterdraw method. 4.2 VALVES All valves used in a tank prover system that can provide or contribute to a bypass of liquid around the tank prover or the meter or to leakage between the tank prover and the meter shall be double block-and-bleed valves, or the system shall be provided with valves and piping that are the equivalent. A method for checking leakage in the valve system is required. 4.3 WIRING AND CONTROLS All wiring devices and controls shall conform to the appli- cable codes. Electrical controls and components should be located in a convenient place for operation and maintenance.
The construction of a tank prover shall be strong and rug- ged enough to prevent distortion of the vessel that would sig- nificantly influence measurement when the tank prover is full of liquid at the proving pressure. Tank provers shall be con- structed to ensure complete drainage of all liquid to the lower reference level without trapping pockets of liquid or sedi- ment. Changes of cross-sections should be gradual and suffi- ciently sloped so that gas bubbles will not be trapped, but will travel to the top of the tank prover. As the tank prover is emp- tied, the liquid will quickly drain. The tank prover should be as self-cleaning as possible so that corrosive products, valve grease, and other foreign matter will not collect inside. Arrangements should be made for peri- odic internal inspection of the tank prover. Lining a tank prover to prevent rust can, in some cases, greatly extend the intervals between calibrations. Gauge glasses should be capa- ble of being cleaned, or swabbed out, without being removed from the tank prover. Appurtenances should be installed in locations that are convenient for quick and practical operation and precise readability.
API MPMS 4.4:1998(R2010) pdf download
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