Custody Transfer Temperature Measurement
API MPMS Chapter 7 – Temperature Measurement Standards
Overview
Presented at 2012 API Asia Conference and Expo
March 6-8, 2012
Dr. William J. Schmidt, II
Director Commercial – Measurement & Loss Control
ConocoPhillips Company
Agenda

API Committee on Measurement Quality (COMQ)

Introduction To Temperature Measurement

Custody Transfer Requirements

Temperature Measurement Standards (API MPMS Chapter 7)

Mercury-In-Glass Thermometers

Summary

Questions & Answers (Q&A)
2
API Committee on Measurement Quality
3
API Committee on Measurement Quality
– As a subcommittee of the Committee on Petroleum Measurement (COPM), COMQ
develops, approves, and maintains standards pertaining to measurement quality
of hydrocarbons, including:
•
•
•
•
•
•
Temperature Determination, MPMS Chapter 7.
Sampling, MPMS Chapter 8.
Density Determination, MPMS Chapter 9.
Sediment & Water Determination, MPMS Chapter 10.
Physical Properties, MPMS Chapter 11.
Truck Gathering, MPMS Chapter 18.
– Joint committee with ASTM International through ASTM Committee D02 as
D02.02.
– COMQ provides representation on the International Organization for
Standardization (ISO) Technical Committee (TC) 28 - Subcommittee (SC) 6, Bulk
Cargo Transfer, Accountability, Inspection and Reconciliation.
4
Introduction To Temperature Measurement
5
Introduction to Temperature Measurement
– Crude oil and petroleum products are typically sold based
on fluid properties at Standard (“Reference”) Temperature
and Pressure conditions.
– Temperature has the most significant effect on the accurate
determination of liquid quantities when correcting to
Standard Conditions (Volumetric Correction Factor).
– Therefore: The most accurate means for temperature
measurement should be used for these custody transfer
applications.
Introduction to Temperature Measurement
– Contracts reference standards to be used in custody
transfer, which specify temperature measurement
equipment, location, and required accuracy.
– Regulatory agencies also reference the same standards for
use in determining royalties, taxes, and regulatory
compliance.
– Buyers and Sellers negotiate the appropriate standards to
be used in the development of contracts for custody
transfer.
Introduction to Temperature Measurement
– Temperature measurement standards are written for:
• Fluids under “static” conditions.
• Fluids under “dynamic” conditions.
– Standards cover temperature measurement for:
•
•
•
•
•
Selection of equipment types and equipment usage.
Volumetric custody temperature measurement.
Calibration of volumetric measurement devices.
Calibration of other temperature measurement devices.
Use in quality analysis (QA).
Custody Transfer Requirements
9
Custody Transfer Requirements
– Static liquid hydrocarbon temperature measurement
• Static vessels:
–
–
–
–
Storage tanks, gathering tanks.
Ships, tankers, and barges.
Tank cars and rail cars
Can provers.
– Dynamic liquid hydrocarbon temperature measurement
• Dynamic vessels:
– Pipes.
– Pipe Provers.
Custody Transfer Requirements
– Static and dynamic temperature measurement
• Objective: find average temperature – representative of “bulk”.
– Manual method:
» Mercury-In-Glass Thermometers (MIGTs).
» Portable Electronic Thermometers (PETs).
– Automatic method:
» Fixed electronic sensors
» Automatic Tank Thermometer elements (ATTs)
Custody Transfer Requirements
– Performance of temperature measurement (Accuracy)
determined by a variety of standards:
•
•
•
•
•
•
•
•
Calculation standard (API MPMS Chapter 12).
Density determination standards (API MPMS Chapter 9).
Sediment and Water determination standards (API MPMS Chapter 10).
Proving standards (API MPMS Chapter 5).
Tank gauging standard (API MPMS Chapter 3).
Tank calibration standard (API MPMS Chapter 2).
Metering standards (API MPMS Chapter 5).
Gathering standard (API MPMS Chapter 18).
Temperature Measurement Standards
13
Temperature Measurement Standards
• Currently, MPMS Chapter 7 contains all temperature measurement
information organized as sections in one document.
– Equipment and apparatus.
– Static Temperature Measurement.
– Dynamic Temperature Measurement.
– Calibration, Verification, and Inspection.
• Ongoing effort to reorganize current document into stand-alone standards:
– Section 1 – Liquid-In-Glass Thermometers.
– Section 2 – Portable Electronic Thermometers (PETs).
– Section 3 – Fixed Automatic Tank Systems (PUBLISHED 9/2011).
– Section 4 – Dynamic Temperature Measurement.
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Temperature Measurement Standards
• Equipment and apparatus section.
– Fixed automatic tank thermometers.
– Portable electronic thermometers (PETs).
– Glass thermometers.
– Electronic temperature devices.
– Thermowells.
– Data Collection, transmission, receiving equipment.
Temperature Measurement Standards
ASTM Thermometers
Name
ASTM
Thermometer
Length (inches)
Graduation
Accuracy
ASTM tank
ASTM tank
58F-80
97F-80
-–30°F to +120°F
0°F to 120°F
12
12
1°F
1°F
± 0.5°F
± 0.5°F
ASTM tank
ASTM tank
59F-80
98F-80
0°F to180°F
60°F to180°F
12
12
1°F
1°F
± 0.5°F
± 0.5°F
ASTM tank
Angle-stem
60F-80
—
170°F to 500°F
Suitable range
12
12a
2°F
1°F
± 1.0°F
± 1.0°F
20°F to 220°F
12
1°F
± 0.5°F
Tank thermometerb
—
Range
Note: Except for the angle-stem thermometer, all thermometers listed in this table are the total-immersion type.
Portable Electronic Thermometer Specifications
Minimum Graduation
Accuracy
Range of Required Accuracy
0.1°F
± 0.2°F
± 0.5°F
± 0.1°C
± 0.3°C
0 – 200°F
> 200°F
0 – 100°C
> 100°C
0.1°C
Note 1: The specifications in this table represent minimum acceptable accuracy for portable electronic thermometers used for custody transfer.
Thermometers with better accuracy are available and may be specified by mutual agreement.
Note 2: PETs shall be provided with displays that provide a resolution of 0.1°C or 0.1°F or better.
Temperature Measurement Standards
• Static temperature determination section.
– Ambient temperature.
– Timing of temperature measurement.
– Fixed automatic tank thermometers.
– Portable electronic thermometers.
– Mercury-in-glass thermometers.
Temperature Measurement Standards
Comparison of Recommended Immersion Times for PETs and Woodback Cup-Case Assemblies
-------------------------------------- Recommended Immersion Times (minutes) ---------------------------------------------Electronic
Thermometer
------------------------------ Woodback Cup-Case Assembly --------------------------------------When Temperature Differential <2.5°C (< 5°F)
API Gravity At 60°F In-Motion (see note 1)
> 50
40 to 49
30 to 39
20 to 29
< 20
.
30 seconds
30 seconds
45 seconds
45 seconds
75 seconds
In-Motion
Stationary
In-Motion
Stationary
5 minutes
5 minutes
12 minutes
20 minutes
45 minutes
10 minutes
15 minutes
25 minutes
45 minutes
80 minutes
5 minutes
5 minutes
12 minutes
20 minutes
35 minutes
10 minutes
15 minutes
20 minutes
35 minutes
60 minutes
Temperature Measurement Standards
Thermometer Assemblies and Temperature Levels for Tanks and Cargo Carriers
Tanks
Typical Temperature
Measurement Facilities
Thermometer
Assemblies
Measurement Levels
Stationary Tanks
Fixed-roof
Floating-roof
Roof hatch
Gauge hatch
Cup-case
Cup-case
See note
See note
Variable vapor space
Gauge hatch
Vertical thermowells
Cup-case
Armored
See note
See note
Pressure lock
Horizontal separable wells
Cup-case
Angle Stem
See note
Three for tank heights less than
10 meters (30 feet); four for tank heights
greater than 10 meters (30 feet)
Gauge hatch
Cup-case
See note
Vertical thermowells
Horizontal separable wells
Armored
Angle-stem
See note
Two, one at middle of tank and one
0.3 meter (1 foot), above bottom
Horizontal-cylindrical
Nonpressure
Pressure
Tank Cars and Tank Trucks
Nonpressure
Pressure
Dome hatch
Vertical thermowells
Cup-case
Armored
Middle of liquida
Middle of liquida
Ships and Barges
Nonpressure
Pressure
Deck hatch
Vertical thermowells
Cup-case
Armored
See note
Middle of liquida
Note: See Table 5 for the minimum number of measurement levels.
a
In special cases, it may be desirable to obtain temperatures at more than one level and calculate a weighted average temperature.
See Table 5, Note 2, for the correct method of averaging multiple temperatures.
Temperature Measurement Standards
• Dynamic temperature determination section.
– Temperature sensor placement.
– Temperature discrimination.
• Calibration verification and Inspection section.
– Fixed automatic tank thermometers (ATTs).
– Portable electronic thermometers (PETs)
– Glass and Mercury-in-glass thermometer verification
– Dynamic verification and calibration.
Temperature Measurement Standards
Maximum Deviation Limits: Temperature Device
Versus Reference Thermometer
Service
°C
°F
Meter Prover Calibration
0.05
0.1
Meter Proving
0.10
0.2
Mercury-In-Glass Thermometers
22
Mercury-In-Glass Thermometers
– World-wide movement to ban mercury in 2000’s.
– Discussed as part of UN activities.
– Commitment by most countries to ban mercury within 2
years.
– MIGT most commonly used
temperature measurement
device in Petrochemical
Industry.
– NIST discontinued calibration
of mercury devices as of
November 2011.
Mercury-In-Glass Thermometers
– Replacement technology:
• Static and dynamic fluid measurements
» Portable Electronic Thermometers (PETs)
» Automatic Tank Thermometer elements (ATT)
• Calibration devices
» ???
• Under study by API MIGT replacement adhoc group
(results in 2012).
• Revise standards to exclude MIGT devices.
Summary
25
Summary
– The most accurate means for temperature measurement
should be used for these custody transfer applications.
– API MPMS Chapter 7 describes the equipment types, usage,
calibration of the various temperature measurements made
in custody transfer.
– Mercury-In-Glass Thermometers will be phased out of the
petrochemical business; standards are being revised to
reflect replacement technologies.
Questions ?
27