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
GB/T 21451.5-2019
NATIONAL STANDARD OF THE
PEOPLE’S 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’s 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 wi...