API MPMS 2.2E 2014 pdf download.Petroleum and Liquid Petroleum Products—Calibration of Horizontal Cylindrical Tanks Part 1: Manual Methods.
1 Scope This part of ISO 12917 specifies manual methods for the calibration of nominally horizontal cylindrical tanks, installed at a fixed location. It is applicable to horizontal tanks up to 4 m in diameter and 30 m in length. The methods are applicable to insulated and non-insulated tanks, either when they are above-ground or underground. The methods are applicable to pressurized tanks, and to both knuckle-dish-end and flat-end cylindrical tanks as well as elliptical and spherical head tanks. This part of ISO 12917 is applicable to tanks inclined by up to 10 % from the horizontal provided a correction is applied for the measured tilt. For tanks over and above these dimensions and angle of tilt, appropriate corrections for tilt and appropriate volume computations should be based on the “Coats” equation . 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 12917. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 12917 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1998 (all parts), Petroleum industry — Terminology ISO 7507 (all parts), Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks 3 Terms and definitions For the purposes of this part of ISO 12917, the terms and definitions given in ISO 1998, ISO 7507-1 and the following apply. 3.1 telescopic rod extendable tubular measuring device to measure a distance between two points NOTE For example, to measure the internal diameter of a cylindrical tank.
4 Precautions 4.1 General The general and safety precautions given in ISO 7507-1 shall apply to this part of ISO 12917. 4.2 Internal method Before a tank which has been used is entered, a safe-entry certificate, issued in accordance with local or national regulations, shall be obtained. All lines entering the tank shall be disconnected and blanked. The national or local regulations regarding entry into tanks which have contained leaded fuels shall be meticulously observed. 4.3 External method National or local regulations regarding entry to the tank area shall be observed. 5 Equipment 5.1 Equipment as used in the ISO 7507 series The equipment required to carry out the calibration is dependent on the method to be employed. This part of ISO 12917 uses techniques and equipment described in ISO 7507-1. Equipment used in the calibration of horizontal tanks shall conform with the specifications laid down in the relevant parts of ISO 7507. All equipment shall be traceable to a reference standard. 5.2 Telescopic rod 5.2.1 In addition to the equipment mentioned in 5.1, a telescopic rod shall be used. This telescopic rod shall have a scale capable of being read to 1 mm, and shall be calibrated to within ± 0,5 mm. 5.2.2 The telescopic rod shall give a repeatability of maximum 1 mm. 6 General requirements 6.1 The tank shall be filled to its normal working capacity and working pressure at least once and allowed to stand while full for at least 24 h prior to emptying and preparing the tank for calibration. NOTE The hydrostatic test applied to new or repaired tanks will satisfy this requirement when additional pressure tests are carried out.8.3 Repetition of measurements After the circumference has been measured, the tension shall be released and the tape brought again to the required level and tension. The readings shall then be repeated and recorded. 8.4 Tolerances Measurements shall be read to the nearest 1 mm and shall be considered satisfactory if two consecutive readings are within ± 0,03 % of the circumference or 3 mm, whichever is greater. If agreement is not obtained, further measurements shall be taken and recorded until two consecutive readings agree. The average of these two readings shall be taken as the circumference. If consecutive measurements do not agree, the reason for the disagreement shall be determined and the calibration procedure shall be repeated. 8.5 Other measurements on tank-shell plates 8.5.1 Plate and paint thickness Plate, paint and any coating thickness shall either be measured for each course, whenever possible, by an ultrasonic device/primary method, or will be taken from the drawings. The plate and paint thickness for each course shall be recorded to the nearest 0,5 mm. Physical measurements are preferred to readings from drawings. 8.5.2 Length of the horizontal cylinder The length of the horizontal tank (cylindrical part) shall be measured at the welding of the first knuckle at four measuring points representative of the length of the tank (see Figure 2). For each measuring point, a reference point shall be marked on the tank. The measurement of the length should be repeated at least twice. Measurements shall be read to the nearest 1 mm and shall be considered satisfactory if two consecutive readings are within 0,03 % of the length or ± 3 mm, whichever is greater. Determine the overall length by taking the average of the two consecutive readings.