API MPMS 2.2D:2003 pdf download

API MPMS 2.2D:2003 pdf download.Manual of Petroleum Measurement Standards Chapter 2—Tank Calibration Section 2D—Calibration of Upright Cylindrical Tanks Using the Internal Electro-optical Distance-ranging Method.
Appendix A. Then select and clearly mark on the tank shell wall two reference target points.
Note 5: The two reference target points should be approximately 100 gon apart and preferably on the same horizontal plane as the instrument.
7.2.3 The slope distances to each of the two reference target points shall be measured. Two successive readings to each reference target point shall be taken. The two readings, at each point, shall agree within ± 2 mm. The average distance to each point shall be calculated. The slope distances shall he recorded.
7.2.4 Wait 15 mm and repeat 7.2.3. The repeated slope distances shall agree within ± 2 mm with the slope distances originally measured. The slope distances shall be recorded.
7.2.5 If the original and repeated average slope distances do not agree within ± 2 mm. determine the reason for the difference.
a. If the reason for differences is due to the instrument and or its stability, repeat the procedure from 7.1.
h. If the instrument was switched off during the determination of the differences, repeat the procedure from 7.2.1.
c. If neither a) nor b) is appropriate, repeat the procedure from 7.2.3
d. Repeat the appropriate procedures until two successive readings agree within ± 2 mm.
8 Selection of Target Points
8.1 Select two sets of target points per course, one at 1/5 to
1/4 of course height above the lower horizontal seam, the other
at 1/5 to 1/4 of course height below the upper horizontal seam.
The number of target points per set, on each course of the tank shell wall, is dependent on tank circumference. The minimum number of target points per set, as a function of tank circumference, is given in Table I and illustrated in Figure 1.
8.2 The target points shall be at least 300 mm from any vertical welded seam.
9 Calibration Procedure
9.1 Sight all of the target points along the horizontal plane at each course location, and measure the slope distance, horizontal angle and vertical angle to each, as illustrated in Figure 2.
9.2 Measure and record the slope distance, horizontal angle and vertical angle to each of the reference target points.
9.3 Complete the measurements to the target points on each course prior to moving to the next course.
Note 6: Measurements should begin at the bottom course and extend, course by course, to the top.
9.4 After all measurements on a course are completed. repeat the measurements to the reference target points.
Note: A number of points greater than the minimum number of points in Table 1 may be chosen depending on specific circumstances and tank conditions.
9.5 If the repeated slope distances to the reference target points do not agree with the measurements taken during the setting up of the instrument, within the tolerance given in 10.1. then repeat 9.1109.5.
9.6 If the horizontal and the vertical angles to the reference target points do not agree within the tolerance given in 10.2, repeat 9.1 to9.5.
9.7 If statistical agreement is not obtained between the original and repeated measurements of slope distances, horizontal angles or vertical angles, then the reasons for such disagreement shall be determined, the cause eliminated and the tank calibration procedure repeated.
9.8 Carry out all measurements without interruption.
10 Tolerances
10.1 REFERENCE TARGET POINT: DISTANCE VERIFICATION
The slope distance to each of the reference target points before and after the tank calibration has been carried out shall be within ±2 mm.
10.2 REFERENCE TARGET POINT: HORIZONTAL AND VERTICAL ANGLE VERIFICATION
The horizontal and vertical angle to each of the reference target points before and after the tank calibration has been carried out shall be within ± 0.001 gon.
11 Other Measurements
11.1 The tank bottom shall be calibrated by the liquid method in accordance with API Standard 2555, or by use of the clectro-optical ranging instrument as a surveyor’s level or by use of a surveyor’s level in accordance with API MPMS Chapter 2.2A, or by use of water-filled tubes in accordance with APi MPMS Chapter 2.2A.