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GB/T 21451.5-2019 English PDF (GBT21451.5-2019)

GB/T 21451.5-2019 English PDF (GBT21451.5-2019)

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GB/T 21451.5-2019: Petroleum and liquid petroleum products -- Measurement of level and temperature in storage tanks by automatic methods -- Part 5: Measurement of temperature in marine vessels

This Part of GB/T 21451 provides the selection, accuracy, installation, debugging, calibration and inspection guidance for automatic tank thermometer (ATT), which is adopted for the measurement of temperature of petroleum and liquid petroleum products in marine vessels. This Part is applicable to the custody transfer metering of petroleum and liquid petroleum products with the Reid vapor pressure of not more than 100 kPa.
GB/T 21451.5-2019
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 75.180.30
E 30
Petroleum and Liquid Petroleum Products -
Measurement of Level and Temperature in Storage
Tanks by Automatic Methods - Part 5: Measurement of
Temperature in Marine Vessels
(ISO 4266-5:2002, MOD)
ISSUED ON: MARCH 25, 2019
IMPLEMENTED ON: OCTOBER 1, 2019
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Terms and Definitions ... 6
4 Requirements ... 7
5 Accuracy ... 8
6 Selection of ATT ... 11
7 ATT Equipment - Instruction of Electronic Temperature Sensing Element .. 12 8 Installation of Marine ATT ... 12
9 Calibration and On-site Inspection of Marine ATT ... 13
10 Data Communication ... 17
Appendix A (informative) Influencing Factors of Temperature Measurement Accuracy of Marine Vessels ... 19
Petroleum and Liquid Petroleum Products -
Measurement of Level and Temperature in Storage
Tanks by Automatic Methods - Part 5: Measurement of
Temperature in Marine Vessels
1 Scope
This Part of GB/T 21451 provides the selection, accuracy, installation, debugging, calibration and inspection guidance for automatic tank thermometer (ATT), which is adopted for the measurement of temperature of petroleum and liquid petroleum products in marine vessels.
This Part is applicable to the custody transfer metering of petroleum and liquid petroleum products with the Reid vapor pressure of not more than 100 kPa. This Part is inapplicable to temperature measurement in refrigerated cargo hold or pressure cargo hold in marine vessels.
2 Normative References
The following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 8927 Petroleum and Liquid Petroleum Products - Temperature Measurement - Manual Methods (GB/T 8927-2008, ISO 4268:2000, MOD);
ISO 1998 (all parts) Petroleum Industry - Terminology
3 Terms and Definitions
What is defined in ISO 1998, and the following terms and definitions are applicable to this document.
3.1 Automatic Tank Thermometer; ATT
Automatic tank thermometer refers to an instrument which continuously measures temperature in storage (or cargo) tanks.
NOTE: a type of marine ATT, also known as automatic tank temperature measurement 4.2.2 All the marine ATTs shall be designed, selected and installed in accordance with corresponding national and/or international (IMO, IEC, CENELEC, ISGOTT, ISO, etc.) vessel electronic safety standards. ATT shall have certified documents that are consistent with the classification of dangerous zones that it is applied to. 4.2.3 In terms of ATT installed on vessels, all the exposed metal components shall be firmly grounded, namely, connected to the vessel body.
4.2.4 All the ATT equipment shall be maintained under safe operating conditions. Equipment maintenance shall be conducted in accordance with the manufacturer?€?s requirements.
4.3 General Requirements
4.3.1 General requirements provided in 4.3.2 ~ 4.3.6 are applicable to various types of ATT.
4.3.2 Temperature and liquid level in marine vessels shall be simultaneously measured. 4.3.3 When temperature measurement is conducted on bulk cargo transportation, the data shall be immediately recorded, unless long-distance digital display equipment can regularly and automatically record the temperature.
4.3.4 During the loading and/or unloading at multiple ports, before the transportation of products (front reading) and after the transportation of products (rear reading), the same standard procedure shall be adopted to measure the temperature in marine vessels.
4.3.5 In order to prevent unauthorized adjustment or intervention, safety guarantee shall be provided to ATT. When ATT is applied to custody transfer metering, certain conditions shall be provided to the sealing of the calibration adjustment device. NOTE 1: this kind of protection might need to install ATT sensor in a temperature casing. NOTE 2: ATT sensor may be integrated in the combination (for example, float, belt or rod) of automatic level gauge (ALG). When some designs (float and belt) are not in service, the combination of liquid level/temperature sensor might be raised to the location of ?€?retention?€?. During the tank-washing period, ATT cannot be used. 4.3.6 When ATT is applied to special occasions, its design and installation might need to obtain type approval from relevant national institutions. After conducting a series of specific tests on ATT and complying with the authorized installation mode, type approval will generally be released.
5 Accuracy
5.1 Overview
circumstances are exceptions here:
---Cargo tank capacity is less than 159 m3, or, liquid level is lower than 3 m; ---The maximum variation of vertical temperature is less than 1 ??C;
---The manually measured average temperature is used for custody transfer metering.
NOTE: when liquid temperature in the vessels is uniform, or, when temperature stratification in the vessels is relatively small and acceptable (see GB/T 8927), single-point temperature measurement may be adopted.
7 ATT Equipment - Instruction of Electronic
Temperature Sensing Element
7.1 Resistance Temperature Detector
In terms of generally used automatic temperature measurement equipment, its basic operating principle is that the resistance of metal (for example, copper or platinum) varies with the temperature.
Generally speaking, copper or platinum RTD is used for temperature measurement in custody transfer metering, because it has extremely high accuracy and stability. The resistance of RTD may be measured through Wheatstone bridge circuit or other suitable electronic components. RTD may be resistance wires intertwined on non- conductor support core, or, thin-film type or other types. This component shall be correctly installed in a stainless-steel shell. If necessary, circuit shall be intrinsically safe. Temperature sensing element shall be installed in a suitable temperature casing. The length of the sensing part of point-type temperature sensing element shall not exceed 100 mm.
7.2 Other Temperature Sensing Element
Other temperature sensing elements (such as thermocouple, thermistor,
semiconductor and optical fiber, etc.) may also be adopted. However, they shall be calibrated and comply with the inspection tolerance provided in this Part, otherwise, it shall not be deemed that their accuracy is applicable to custody transfer metering. 8 Installation of Marine ATT
8.1 Overview
The installation of marine ATT shall comply with the requirements in the instructions provided by ATT and ALG manufacturer.
applied for temperature measurement in custody transfer metering, the calibration tolerance provided in this Part shall be satisfied. The reference standard of ATT calibration shall be traceable to corresponding national standards.
NOTE 1: precise electronic temperature element and on-site transmitter used for fixed automatic tank thermometer need to be calibrated before installation. Generally speaking, on-site calibration adjustment device for transmitter will not be provided.
NOTE 2: the objective of 9.2 ~ 9.4 is to inspect the calibration adequacy and accuracy of ATT (including temperature element, transmitter and on-site/long-distance digital display device) after its installation.
When manual temperature measurement is adopted to inspect or calibrate ATT, manual temperature measurement shall be conducted in accordance with GB/T 8927. The uncertainty of the reference standard for on-site calibration shall not exceed 0.1 ??C (necessary calibration correction value shall be adopted).
ATT may be calibrated/inspected in accordance with system or component. 9.2 Calibration and Inspection of Single-point ATT for Custody Transfer Metering
9.2.1 Calibration before installation
The reference standard of ATT calibration shall be traceable to corresponding national primary standards. Before installation, single-point ATT shall be calibrated under controllable conditions (namely, factory or laboratory) in accordance with one of the two methods below:
a) In three or more temperature points within ATT?€?s operating range, through thermostatic bath and use standard thermometer to measure its temperature. Conduct overall calibration of ATT (including temperature sensor, temperature transmitter/converter and digital display device); the requirement of accuracy is shown in 5.3.2.
b) Or, independently calibrate ATT components. Measure the resistance of temperature element in thermostatic bath; use accurate resistor or thermal calibrator (recently calibrated by a national metering institution). Respectively simulate the input temperature of ATT temperature transmitter and digital display device; the requirement of accuracy is shown in 5.3.3.
9.2.2 Initial inspection in shipyard or sea trial
9.2.2.1 Overview
In shipyard or sea trial, in accordance with ATT manufacturer?€?s instruction, conduct a relatively low accuracy of temperature measurement of shipping cargos. 9.3 Calibration and Inspection of Multiple-point ATT for Custody Transfer Metering
9.3.1 Calibration before installation
In accordance with the calibration procedure of single-point ATT provided in 9.2.1, inspect every temperature sensing element of ATT. Please refer to 5.3.4 for the requirement of accuracy.
9.3.2 Initial on-site inspection in shipyard or sea trial
9.3.2.1 Overview
In shipyard or sea trial, in accordance with ATT manufacturer?€?s instruction, conduct initial inspection and debugging. When it is feasible, a method provided in 9.3.2.2 and 9.3.2.3 shall be adopted.
9.3.2.2 Component-based inspection
9.3.2.2.1 Temperature sensing element
Use a recently calibrated PET to inspect temperature sensing element?€?s measurement data. When cargo hold approaches fully-loaded state, lower PET temperature measuring probe to the depth of placement of the temperature sensing element; move the temperature sensing probe up and down (within the range of around 300 mm), till the temperature becomes stable. The difference between the temperature measured by each temperature sensor of multiple-point ATT and the temperature measured by PET shall be within 0.75 ??C.
9.3.2.2.2 Temperature transmitter
Use temperature calibrator (for example, precise resistor or thermal calibrator) to simulate the input of three or more temperatures within the expected operating range of the vessels. Conduct inspection of ATT, excluding the temperature element. In each temperature point, the difference between ATT digital display temperature and resistor?€?s equivalent temperature shall be within 0.25 ??C.
9.3.2.3 System-based inspection
As an alternative method for independent calibration and inspection of temperature sensing element and transmitter, PET, which is calibrated before the inspection, may be adopted to conduct overall inspection of ATT; it would be better if the storage tank approaches fully-loaded state, and all the temperature sensing elements are completely immersed. Measure the liquid temperature in the depth of the temperature sensing element. In each measurement location, move PET temperature measuring probe up and down (within the range of around 300 mm), till the temperature becomes

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