GB/T 17605-1998 Petroleum and liquid petroleum products — Calibration of horizontal cylindrical metal tanks — Manual method

Summary page. This page is a compiled excerpt/summary of the standard — it is not the full standard text and does not replace it. Verify every value against the official standard and the product certificate before use.

GB/T 17605-1998, Petroleum and liquid petroleum products — Calibration of horizontal cylindrical metal tanks — Manual method, specifies the measurement and calibration of fixed horizontal cylindrical metal tanks.

Evidence note: For the 1998 edition, partial supplementary learning text: based on the 22-page original held, the deduction of fittings, the volume composition, the temperature correction of the 20 °C capacity table and the reporting boundary were checked. Technical review is pending; the long-form equations for complex heads, angular units and unclosed boundaries are retained; this is not a complete algorithm, a controlled operating procedure or a product applicability commitment.

Scope: Chapter 1 Scope: This standard specifies the method for measuring and calibrating fixed horizontal cylindrical metal tanks. Not applicable: the available material does not provide an explicit exclusion clause. Related note: 5.6 In certain special cases, such as severely deformed tanks or underground tanks that cannot be entered, it is recommended to use the liquid calibration method for all or part of the tank volume in place of the measurement and calibration method for tank volume. 21.12.1 When the tilt ratio (tgβ) is not greater than 0.06, the volume is calculated by formula; when it is greater than 0.06, the liquid calibration method is recommended.

Principle: All the data required to compile a tank capacity table, and the methods by which these data are obtained, must be guaranteed by a rigorous measurement principle. By external measurement (length of the main cylinder, circumference, head dimensions, tilt, fittings, etc.) or internal measurement (Annex A), the total volume and partial volumes of the main cylinder, the straight flange of the heads and various heads (dished, spherical-cap, hemispherical, semi-ellipsoidal, conical, frustum, flat) are calculated; the volume of in-tank fittings is deducted or added, and the tank capacity table is compiled. 18 Calculation tolerance: tank dimensions are calculated to 0.01 mm; tank volume is calculated to 0.01 L. 24 Total uncertainty (95 % confidence level): the total uncertainty of the volume calibration is not greater than 0.3 %.

Apparatus: Steel tape (circumference tape): 0 to 15 m, conforming to the requirements of GB 13236. 4.2 Dip tape (sounding tape): 0 to 5 m, conforming to the requirements of GB 13236. 4.3 Steel rule: a) 0 to 1 m, scale interval 1 mm; b) 0 to 30 cm, scale interval 1 mm. 4.4 Telescopic rod gauge: scale interval 1 mm. 4.5 Radius tri-square: spans 0 to 350 mm and 0 to 1 000 mm, scale interval 1 mm; readable to 0.1 mm by means of the reading device. 4.6 Thickness gauge: 0.2 mm. 4.7 Level: class S₃. 4.8 Steel trammel: fixed or adjustable type. 4.9 Thermometer: total-immersion mercury thermometer, −30 to +50 °C, scale interval 0.2 °C. 4.10 Force gauge: measuring range 0 to 100 N, minimum scale interval 2 N. 4.11 Radius gauge: five sliding measuring scales mounted on a graduated steel bar 2 m long, minimum scale interval 1 mm; readable to 0.1 mm by means of the reading device. 4.12 Others: tape hooks, plumb bobs, magnetic bases, etc. 4 General: it is not necessary to use all the tools listed for the measurement of any one tank; the tank structure and the corresponding measurement method must be carefully considered before selecting tools; the tools used shall be in good condition; the steel circumference tape and the dip tape shall not be bent or kinked.

Key conditions: The tank shall be subjected to at least one pressure cycle, with the pressure reaching the maximum working pressure of the tank, or filled with water, and shall be stable for 72 h before measurement. 6.3 The interior of the tank shall be clean, and the measurement locations shall be free of any impurities such as oil residues, dirt and rust adhering to the tank bottom and side walls. 5.1 In all cases, the safety regulations in force shall be observed. 5.2 The number of persons in the measurement team depends on the site conditions (experience of the personnel, weather conditions, measurement schedule and tank size). 5.3 Ropes, ladders or other equipment of doubtful strength or condition shall not be used; this is especially important for ropes that are damp, soaked with oil products, or have been used on acid tanks. 5.4 When ladders are used, all rungs shall be inspected and tested on the ground; ladders shall not be extended beyond the normal safe range. 5.5 The measured values and descriptive information obtained on site shall be checked and recorded promptly and clearly. 10.5 / 11.1.5 / A2.2 / A4.2 A tensile force of 50 N is applied to the steel circumference tape during measurement. 7 Reading tolerances: 7.1 Circumference measurement with the steel tape: read and record to 0.5 mm. 7.2 Measurement of main cylinder length, total head length, head straight flange length, tilt, etc.: read and record to 0.5 mm. 7.3 Measurement of transition curve radius: read and record to 0.2 mm. 7.4 Measurement of spherical-cap radius: read and record to 0.2 mm. 7.5 Temperature value: read and record to 0.2 °C. 7.6 Measurement of tank plate thickness: read and record to 0.2 mm. 7.7 Measurement of in-tank fittings: read and record to 1 mm. A3.5 The internal diameter shall be read and recorded to 0.5 mm.

Annex volumes and volume composition: Equation (49): V₄ = m/ρ × 10³. Mass of fittings m (kg), density of steel ρ (kg/m³), result V₄ (L); the influence of steel ladders, stiffening rings, supports, etc. is related to liquid level, and local fittings need to be measured accordingly; it cannot be assumed that all fittings are uniformly distributed. Equation (50): V = V₁ + V₂ + V₃ − V₄. Equation (51): V_H = V₁H + V₂H + V₃H − V₄H. The volumes (L) correspond respectively to the main cylinder, the head straight flange, the head and the fittings; fittings are deducted or added according to whether they displace or contain liquid, and the signs must not be separated from their original definitions. θ was originally defined in rad or degrees, yet some partial-volume equations contain both θ itself and trigonometric functions, so the angular unit must be unified in calculation. Complex equations 29 and 48 have not been fully reconstructed; these boundaries are not to be guessed through OCR, trends or another version.

Capacity table at 20 °C, temperature correction and reporting: The capacity table gives volumes at 20 °C. For custody transfer measurement, equation (C1): V_t = V₂₀[1+β(t_s−20)], where β is the expansion coefficient of the tank shell, 34.5×10⁻⁶/°C, not the tilt angle β of the main text, and cannot be replaced by the liquid expansion coefficient. t_s is the tank shell temperature (°C): for an insulated tank, take the liquid temperature in the tank; for a non-insulated tank, if the difference between the liquid temperature and the ambient temperature is <40 °C, take the average of the liquid temperature and the surrounding air temperature; if >40 °C, measure the shell temperature at 4 or more equally spaced points around the circumference and take the average. The original branch for exactly 40 °C is not closed, so ≤ or ≥ is not supplied. The capacity table is compiled at 1 cm liquid height intervals, the millimetre part may be interpolated, and volume values are accurate to the litre; the calculated 0.01 L must not be taken directly as the number of decimal places of the external table. In accordance with Annex C, the report retains the tank number/location/type/design volume, calibration unit/date/signature and results. B1 record, C1 certificate cover and C2 capacity table are all blank formats rather than actual measured data or issued certificates; where no measurable data are available nothing is fabricated, and the templates have not been turned into controlled records. The total uncertainty of volume calibration is not greater than 0.3 % at the 95 % confidence level. This is not a statement of repeatability r/reproducibility R or of automatic acceptance of every field point, nor does the 0.01 L calculation precision prove that requirement.

Verification note: [To be verified] and [source unclear] mark points that still need to be checked against the original standard text; they do not mean the values have been verified. Do not use these values or procedures directly as a basis for work. This round added the volume of fittings and the total/partial volume composition, the temperature correction of the 20 °C table and the reporting boundary. Complex head equations 29/48 have not been fully reconstructed; the θ angular unit and the tilt β=0 must be checked separately; the original text for a temperature difference of exactly 40 °C is not closed. Annexes B/C are blank templates, not measured data or issued certificates. Chapter 18's 0.01 mm/0.01 L is calculation precision; Chapter 24's 0.3 % is the total uncertainty at the 95 % confidence level, and no claim of technical acceptance is made.

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