Jul,02

API MPMS 2B-2002 pdf download

API MPMS 2B-2002 pdf download

API MPMS 2B-2002 pdf download.Manual of Petroleum Measurement Standards Chapter 2-Tank Calibration Section 2B- Calibration of Upright Cylindrical Tanks Using the Optical Reference Line Method .
The optical reference line method (ORLM) is an alternative method to the manual tank strapping method (MTSM) for determining tank diameter. The primary difference between the ORLM and the MTSM is the procedure for determining tank diameter at shell courses other than the bottom course. The ORLM provides for measuring a reference diameter on the bottom course by manual strapping and measuring deviations in tank diameter at other predetermined horizontal and vertical stations by using an optical device. The other required special measurements. procedures, methods. and analytical tools for the development of a tank capacity table are identical to those stated in API Standard 2550. 2.2B.2 Scope This standard describes measurement and calcula- tion procedures for determining the diameters of up- right welded (lap/butt) cylindrical tanks, or vertical cylindrical tanks, with a smooth outside surface and either floating or fixed roofs. This standard should be used in conjunction with API Standard 2550. For external application of the ORL .M on insulated tanks, the insulation must be removed. The ORLM may be used on the interior of the tank; however, when the reference circumference on the bottom course is established externally, the insulation al the bottom ring must be removed. This measurement shall conform to the procedures described in API Standard 2550. Abnormally deformed tanks (that is, tanks that are dented or have other visible signs of damage) should be repaired before any calibration is undertaken.
2.2B.3.4 The reference offset is the measurement observed through an optical device on the horizontal scale of a traversing magnetic trolley at the vertical station on the bottom plate. 2.2B.3.5 The reference circumference is the circum- ference of a tank measured by the MTSM on the bottom ring. 2.2B.3.6 The reference radius is the reference cir- cumference divided by 2π. where π= 3.141593. 2.2B.3.7 An optical device is an optical plummet or a theodolite equipped with a precision level. 2.2B.4 Referenced Publications The following publications are referenced in this chapter: API Std 2550 Measurement and Calibration of Upright Cylindrical Tanks (ANSI/ASTM D 1220) Manual of Petroleum Measurement Standards Chapter 1, “Vocabulary” 2.2B.5 Significance Accurate tank circumference/radius measurements are critical in determinations of liquid volume. These measurements are infuenced by both random ertors associated with physical measurements and systematic errors associated with the particular device and/or procedure used. The combination of random and systematic errors has an impact on the overall preci- sion, or accuracy, of any measurement. The ORLM is as precise as the MTSM and can be used as an altermative method of determining tank circumferences or diameters (radi).
c. The perpendicularity shall be verifed (see 2.2B.7.3). and the reference offset (for example, Distance a in Figures 3 and 4) shall be measured from the first horizontal station. d. The trolley shall be vertically traversed to the next predetermined vertical station in each ring, and the offset (for example. Distance m in Figures 3 and 4) shall be read. This procedure shall be repeated se- quentially at each of the vertical stations. e. After the offset in the topmost course is read, the trolley shall again be lowered to the bottom ring and the reference offset measurement shall be repeated. The initial and fnal reference offsets at each horizontal station shall be within 0.005 foot (or 1 millimeter) of each other. If the initial and final reference offsets for a horizontal station do not agree within 0.005 foot (or 1 millimeter), the procedure should be reinitiated, beginning with Step c. f. Steps b e shall be repeated for each horizontal station. g. After the optical measurements around the tank are completed, the reference circumference measurement (Step a) shall be repeated using the same master tape. The initial and final readings shall agree within 0.005 foot (or I millimeter). If they do not agree

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