API MPMS 2.2F:2004 pdf download
API MPMS 2.2F:2004 pdf download.Petroleum and Liquid Petroleum Products- Calibration of Horizontal Cylindrical Tanks Part 2: Internal Electro-optical Distance-ranging Method.
8.2 Location of target points — General principle
Target points shall be located on each surface, randomly but distributed over the entire surface. No target points shall be positioned within 300 mm of a welded seam or stiffener,
NOTE It is not a requirement of this method that any particular point be used as a target point
8.3 CylIndrical courses
A minimum of 16 target points per course in tanks of diameter less than 3 m, and a minimum of 24 target points per course in tanks of diameter 3 m or greater, shall be sighted. The uncertainty of califration will be reduced if the number of target points is greater than the minimum specified.
8.4 Heads
8.4.1 FIat end, elliptical, spherical head, conical head
A minimum of 50 target points, randomly but evenly distributed over the surface, shall be sighted. The uncertainty
of the calibration will be reduced If a greater number of target points Is used.
8.4.2 Knuckle-dished end (head)
A minimum of 16 target points, randomly but evenly distributed over the surface, shall be sighted. The uncertainty or the calibration will be reduced If a greater number of target points Is used.
9 Procedure for calibration
9.1 Measure and record the horizontal angle, the vertical angle and the slope distance to each reference target point. Two successive readings, at each point, shall be taken and they shall agree within the tolerance given in clause 10, Compute and record the average angles and distance to each point.
9.2 Measure the honzontal and vertical angles and the slope distance to each target point on a surface. See Figure 2.
9.3 If more than one measurement station is required, move the instrument from station to station, taking sufficient measurements at each station to ensure a proper traverse.
9.4 After all measurements from one measurement station are completed, repeat the measurements to the reference target points.
9.5 If the repeated horizontal and vertical angles and slope distances to each reference target point do not agree with the measurements taken in 9.1. within the tolerances given in dause 10, determine the reasons for such disagreement, eliminate the cause and repeat the calibration procedure.
9.6 Commence measurements at one head and progress through the tank to the other head.
9.7 Carry out all measurements without interruption.
10 Tolerances of reference target points
10.1 Distance verification
From each measurement station, the slope distance to each reference target point at the beginning and end of the calibration shall be within ± 2 mm.
A.1 Set up a stadia of 2 m土1 mm (his can be undertaken in the laboratory).
A.2 The stadia may be temperature compensated to maintain a distance of 2 m automatically by external
compensation or may be compensated manually.
A.3 Mount the stadia on a floor or in a tank as indicated in Figure A.1 and level the stadia.
A.4 Mount the tripod with EODR, as ilustrated in Figure A.1.
A.5 For a given distance, D, establish coordinates of target points A and B on the reference bar.
A.6 Compute the distance AB from EODR instruments.
A.7 The maximum variation between the value of AB computed in A.6 and 2 m shall be土3 mm.
A.8 Increase the distance D, remeasure the angles to the fixed points A and B on the stadia. Compute the distance AB using the remeasured angles. Continue this procedure until the variation between the computed value of AB and the standard length of the stadia exceeds 土3 mm. Note the smaller angle, of the two measured, and record it as the limiting angle of incidence.
