A tank strapping table is the lookup chart that turns a tank level reading into an actual volume. Because a real tank is never a perfect cylinder, you cannot compute its contents from height alone - you need its measured capacity table. This guide explains what a strapping table is, how a tank is strapped, and how the table is used to get volume in the field and in SCADA.
Tank Strapping Table in one line: A tank strapping table (or gauge/capacity table) is a calibration chart that maps a tank's liquid level to the volume it contains at each height. It is produced by physically measuring - strapping - the tank, and it is what converts a level reading into a barrels or gallons figure for inventory and custody.
A storage tank is never a perfect geometric shape. The shell bulges slightly under liquid load, plates have thickness, there are internal structures (heating coils, a floating roof and its legs, deadwood), and the bottom may not be flat. So a simple height x area calculation would be wrong, especially near the bottom and top. The strapping table captures the real, measured relationship between level and volume, typically as an incremental volume for each unit of height (for example barrels per inch, or a volume value at every quarter inch).
With the table, a gauged level of, say, 12 feet 4 inches is looked up (or interpolated) to a precise gross volume. For custody-grade work the table also accounts for corrections such as shell temperature and, where relevant, the displacement of a floating roof.
Strapping is the process of calibrating the tank to build the table. The traditional method wraps a calibrated steel tape (a strap) around the tank at multiple heights to measure circumference, from which the internal cross-sectional area at each level is derived. Modern methods use optical or electro-optical distance-ranging (EODR) or laser scanning to measure the shell geometry without a tape. Bottom calibration and any internal deadwood are measured separately and subtracted.
The procedures and accuracy requirements are defined by standards - the API Manual of Petroleum Measurement Standards (MPMS) Chapter 2 covers upright cylindrical tank calibration. A tank is re-strapped periodically or after significant repair, because a changed shell or bottom changes the table.
In manual operation, a pumper gauges the level and reads volume from the printed strapping (gauge) table, applying temperature and BS&W corrections for a net standard volume. Automated tank gauging systems and flow computers store the strapping table digitally and apply it in real time, so the tank's level reading is continuously converted to gross and net volume without a person looking anything up.
When a cloud SCADA such as Merobix reads a tank's volume tag over Modbus or DNP3, that value has usually already had the strapping table applied by the ATG console or flow computer at the site. The strapping table is the reference standard that makes every barrel figure - and therefore inventory and custody reconciliation - defensible.
It is a calibration chart that maps a tank's liquid level to the volume it holds at each height. Because a real tank is not a perfect cylinder, the table - built by physically measuring the tank - is what converts a level reading into an accurate barrels or gallons figure for inventory and custody.
Traditionally by wrapping a calibrated steel tape around the tank at several heights to measure circumference and derive cross-sectional area, then measuring the bottom and internal deadwood separately. Modern methods use optical or laser scanning. The procedures follow standards such as API MPMS Chapter 2.
They are effectively the same thing - a strapping table is the volume-versus-level chart produced by strapping (calibrating) the tank, and gauge table or capacity table are common alternative names for that same lookup used to convert a gauged level into volume.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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