API MPMS 3.1B:2001 pdf download

API MPMS 3.1B:2001 pdf download.Manual of Petroleum Measurement Standards Chapter 3- Tank Gauging.
3.1 B.4.4.1 Use of ATGs for Custody Transfer Purposes
3.1 B.4.4.1 .1 The ATG should meet the factory calibration tolerances prior to installation (refer to Section 3.IB.4.3.2).
3.1 B.4.4.1 .2 The ATG should meet the field verification tolerance for custody transfer (refer to Section 3.IB.7.3.3), including the effects of installation methods and changes in operating conditions (refer to Section 3.IB.4.3.3).
3.1 B.4.4.2 Use of ATGs for Inventory Control Purposes
3.1 B.4.4.2.1 The ATG should meet the factory calibration tolerances prior to installation (refer to Section 3.1 B.4.3.2).
3.1 B.4.4.2.2 The ATG should meet the field verification tolerance for inventory control (refer to Section 3.1B.7.3.3), including the effects of installation methods and changes in operating conditions.
3.1 B.4.4.3 Remote Readout Custody Transfer
The remote readout, if used, should meet the requirements of this standard (refer to Section 3.1 B.4.6).
3.1 B.4.5 INSTALLATION OF ATGs
3.1 B.4.5.1 Manufacturer’s Requirements
The ATG and the associated electronics should he installed and wired in accordance with the manufacturers’ instructions, NFPA National Electrical Code and/or local standards.
3.1 B.4.5.2 Mounting Location of UIIage-ATGs
The mounting location of an ATG may affect its accuracy after installation. The mounting location of the ATG should be such that the ATG may be easily verified by manual gauging from the official gauge hatch.
For custody transfer accuracy, it is essential that the mounting location should be stable, with minimal vertical movement with respect to the tank reference (which is typically the joint where the tank shell and bottom meet). If the datum plate is found to be stable, it may be used to verify the stability of ATG mounting.
The stability of the mounting location is affected by the changes in liquid head, vapor pressure or loading of the roof or gauging platform.
For best accuracy, an ullage-ATG should be mounted on a properly supported. slotted (or perforated) still pipe, as illustrated in Figures 1 and 2.
3.1 B.4.5.2.1 Top Mounting With a Slotted Still Pipe
Figure 1 shows an ullage-ATG mounted on a slotted still pipe supported by tank bottom. Figure 2 shows an ullageATG mounted on a slotted still pipe supported by a bracket.
Ullagc-ATGs mounted on properly supported slotted still pipes, as illustrated in Figures 1 and 2, deliver higher accuracy because the slotted still pipe is supported on a stable location and ATG movement is minimized when the tank is filled or emptied.
3.1 B.4.5.2.2 Top Mounting Without a Slotted Still Pipe
Alternatively, an ullage-ATG may be supported on the roof of a fixed-roof tank or on a “gallows” on a fixed or floating roof tank, as illustrated in Figure 3. This kind of mounting may cause the ATG to move vertically when the tank is filled or emptied. Ullage-ATGs mounted without slotted still pipes can be used for custody transfer or inventory control if the ATG as installed, can he verified to meet the requirements set forth in Section 3.1 B.4.3.4.
3.1 B.4.5.2.3 Mounting Without a Slotted Still Pipe for SmallTanks
For small (less than 500() barrels) tanks, an ullage—ATG may be mounted without a slotted still pipe. The Reference Height variation should be measured with the tank full and empty.
3.1 B.4.5.3 Mounting Location of lnnage-ATGs
The gauge head of an innage-ATG may he mounted in any suitable location. The mounting location of the ATG should be such that the ATG may be easily verified by manual gauging from the official gauge hatch.
The zero point of the measuring element should be mounted at a stable location on the tank bottom that has mini— mal vertical movement with respect to the bottom corner (which is the joint where the tank shell and bottom meet).
3.1 B.4.5.3.1 Mounting lnnage-ATGs.