ISO 7507-1:2003 石油および液体石油製品—垂直円筒形タンクの校正—パート1：ストラップ方法 | ページ 6

3.1

argument

independent variable of a function

Note 1 to entry: A table is entered with value(s) of the independent variable(s), the value(s) extracted from the table being known as the dependent value(s).

3.2

bottom calibration

procedure to determine the quantity of liquid contained in a tank below the calibration datum-point

3.3

calibration

process of determining the capacity of a tank, or the partial capacities corresponding to different levels

3.4

capacity

total volume of a tank

3.5

capacity table

tank table

tank capacity table

table showing the capacities of, or volumes in, a tank corresponding to various liquid levels measured from a stable reference point

3.6

course

one circumferential ring of plates in a tank

3.7

calibration datum-point

point used as the datum in the preparation of a calibration table

Note 1 to entry: Course heights and the effective levels of deadwood are measured from this point, to which the bottom calibration is also related.

3.8

deadwood

any tank fitting that affects the capacity of the tank

Note 1 to entry: Deadwood is referred to as “positive deadwood” when the capacity of the fitting increases the effective capacity of the tank, or “negative deadwood” when the volume of the fitting displaces liquid and reduces the effective capacity.

3.9

dip

innage

depth of a liquid in a tank above the dipping datum-point

3.10

dip-hatch

gauge-hatch

opening in the top of a tank through which dipping and sampling operations are carried out

3.11

dip-point

point on the dip-plate which the dip-weight touches during gauging and from which the measurements of the oil and water depths are taken

Note 1 to entry: The dip-point usually corresponds to the datum-point, but when this is not so, the difference in level between the datum-point and the dip-point has to be allowed for in the calibration table.

3.12

dip-plate

striking-plate positioned below the dip-hatch

Note 1 to entry: The position of the dip-plate should not be affected by bottom or wall movements.

3.13

dip-tape

graduated steel tape used for measuring the depth of the oil or water in a tank, either directly by dipping or indirectly by ullage

3.14

dip-weight

weight attached to a steel dip-tape, of sufficient mass to keep the tape taut and of such shape as to facilitate the penetration of any sludge that might be present on the dip-point or the dip-plate

3.15

floating cover

screen

lightweight cover of either metal or plastics material designed to float on the surface of a liquid in a tank

Note 1 to entry: The cover rests upon the liquid surface and is used to retard evaporation of volatile products in a tank.

3.16

floating-roof tank

tank in which the roof floats freely on the surface of the liquid contents, except at low levels when the weight of the roof is taken through its supports by the tank bottom

3.17

function

when two variable quantities are interrelated, one quantity is said to be a function of the other

Note 1 to entry: In the context of tank calibration, the volume of liquid contained in a tank is said to be a function of the dip or of the ullage.

3.18

gauging

process of taking all the necessary measurements in a tank in order to determine the quantity of liquid that it contains

3.19

interpolation

process of obtaining the value of a function corresponding to a value of the argument intermediate between those given

3.20

Littlejohn grip

quick-release clamp that may be fitted around a strapping tape at any convenient position throughout its length

Note 1 to entry: A handle is attached to the Littlejohn grip so that the strapping tape can be pulled to the correct tension.

3.21

open capacity

calculated capacity of a tank or part of a tank before any allowance has been made for deadwood

3.22

reference height

vertical distance between the dip-point and the upper reference point

3.23

overall height

total external height from the top of the shell to the base of the tank (plate)

3.24

referee method

application of the strapping method of tank calibration to give a calibration of a tank for custody transfer purposes or to provide a basis for assessing the accuracy of other methods of tank calibration

3.25

reference method

application of the strapping method of tank calibration to the measurement of a reference circumference for use in other methods of tank calibration

Note 1 to entry: An example of such a method is the optical-reference-line method (see ISO 7507-2).

3.26

reference point

a point to which measurements in either calibration or gauging are related

3.27

step-over

device used in strapping for measuring the distance apart, along the arc, of two points on a tank shell where it is not possible to use a strapping tape directly because of an intervening obstruction, e.g. a protruding fitting

3.28

step-over constant

distance between the measuring points of a step-over as measured along the arc of the particular course of the tank concerned

3.29

step-over correction

difference between the apparent distance between two points on a tank shell as measured by a strapping tape passing over an obstruction and the true arc distance as measured by a step-over, i.e. the step-over constant

3.30

strapping tape

specially designed and calibrated steel measuring tape graduated in units of length and used for taking circumferential measurements in tank calibration

3.31

strapping method

method of tank calibration in which the capacities are calculated from the measurement of the external circumferences, due allowance being made for the thickness of the shell of the tank

3.32

tape positioner

guide sliding freely on the strapping tape, used to pull and hold it in the correct position for taking measurements

3.33

tensioning handles

handles fastened to the strapping tape, used for pulling it into the correct position and applying tension

3.34

ullage

outage

capacity of a tank not occupied by the liquid

3.35

upper reference point

point clearly defined on the dip-hatch directly above the dip-point to indicate the position at which dipping or ullaging shall be carried out

3.36

working method

application of the strapping method of tank calibration by a simplified procedure that may result in some loss of accuracy and is unsuitable for assessing other methods