Cegelec 2007 25431: Reconciliation 1

RECONCILIATION

Reconciliation

Flow Chart Calibration

Meter Readings

Manual Gauging Figures

Automatic Gauging Figures

Loading-Shipping Figures

Cegelec 2007 25431: Reconciliation 2

Lesson Objectives

At the end of this Lesson You will be Able to:

Describe the process of reconciliation

Describe a flow chart calibration method

Explain the process for preparing meter readings for reconciliation

Describe the process for preparing gauging readings for reconciliation

Describe the process for preparing ATG readings for reconciliation

Describe the process for preparing loading-shipping figures

Cegelec 2007 25431: Reconciliation 3

Defining Reconciliation

The inventory reconciliation procedure entails taking a

volumetric measurement of the product from a port in the tank

(a "stick reading") and comparing this volume with the

expected volume, based on the prior end volume measurement,

sales and deliveries (a "book reading").

Combined with periodic

tank tightness tests, it is

also a temporary leak

detection method, which

may be used to evaluate

the integrity of

underground storage

tanks (UST).

Cegelec 2007 25431: Reconciliation 4

Dipstick Readings

Each dipstick is specific to the

dimensions of an individual tank so it is

important to check that it is the correct

one for the tank and that there are no

signs of wear on the dipstick. Each

division on a dipstick represents a

volume of fuel, so the divisions at the

middle of the tank are smaller than those

at the top and bottom of the tank

Dipstick at the bottom

of the tank

If the bottom 5 cm is missing from a dipstick the stick will sit 5 cm lower in the

tank. At the bottom of the tank 5 cm is equivalent to 1 division on the dipstick,

which represents 1 unit of volume (in this example 1 division = 100 litres).

Therefore this short dipstick would measure 600 litres of fuel when there are

only 500 litres in the tank

Cegelec 2007 25431: Reconciliation 5

Theory of Reconciliation - Calculation

Cegelec 2007 25431: Reconciliation 6

Automatic Tank Gauging (ATG)

ATG is programmed to monitor volume changes in

underground storage tanks. It consists of a panel on a wall

and probes that sense product level and temperature changes.

ATG has two modes: inventory mode and leak test mode.

When an ATG is in the inventory mode, it provides information about product level, volume, and temperature.

When the ATG is in the leak test mode, it is checking for product level changes that may indicate a leak.

The following records must be kept as long as the ATG is used:

Documentation of the manufacturers written performance claims. Documentation of the manufacturers written maintenance and calibration schedules.

Cegelec 2007 25431: Reconciliation 7

Calibration Charts

Each tank should be provided with its own

calibration chart. It is important to use only that

chart associated with that tank, unless the tanks

are all of the same volume and manufactured by

the same company. Each chart is to be calibrated

to 1/8 inch to gallon conversions.

Considerations for calibration of

storage tank:

Newly Constructed After any structural modifications In conjunction with an API 653 Inspection

Minimal 15 years intervals as recommended by API

Cegelec 2007 25431: Reconciliation 8

Statistical Inventory Reconciliation (SIR)

Statistical inventory reconciliation analyzes

inventory, delivery, and dispensing data

collected over a period of time to determine

whether or not a tank system is leaking

To be allowable as monthly

monitoring, a SIR method

must be able to detect a

leak at least as small as 0.2

gallons per hour and meet

the requirements regarding

probabilities of detection

and false alarm. Data must

be submitted monthly

Statistical Inventory Reconciliation

should not be confused with other

release detection methods that also

rely on periodic reconciliation of

inventory, withdrawal, or delivery

data. Unlike manual tank gauging,

automatic tank gauging systems, or

inventory control, SIR uses a

sophisticated statistical analysis of

data to detect releases

Cegelec 2007 25431: Reconciliation 9

SIR Typical Log Form

Cegelec 2007 25431: Reconciliation 10

Lesson Objectives

You should now be Able to:

Describe the process of reconciliation

Describe a flow chart calibration method

Explain the process for preparing meter readings for reconciliation

Describe the process for preparing gauging readings for reconciliation

Describe the process for preparing ATG readings for reconciliation

Describe the process for preparing loading-shipping figures