JJF 1126-2004 Calibration specification for ultrasonic thickness gauge JJF1126-2004 Standard download decompression password: www.bzxz.net
This calibration specification is applicable to the calibration of ultrasonic thickness gauges with a resolution of 0.1mm and 0.01mm.

National Metrology Technical Specification of the People's Republic of China JJF1126-2004
Calibration Specification for Ultrasonic Thickness Instruments2004-09-21Promulgated
Implementation from 2005-03~21
Promulgated by the General Administration of Quality Supervision, Inspection and Quarantine JJF1126—-2004
Calibration Specification for
Ultrasonic Thickness Instruments JJF1126—-2004
Replaces JJG403—1986
This specification was approved by the General Administration of Quality Supervision, Inspection and Quarantine on September 21, 2004, and came into effect on March 21, 2005.
Responsible unit: National Technical Committee for Geometry and Length Metrology Main drafting unit: Tianjin Metrology Technology Research Institute China Institute of Metrology
Participating drafting unit: Times Group Corporation
This specification shall be interpreted by the responsible unit
Main drafters of this specification:
Wang Xinhang
Liu Jiali
Participating drafters:
Peng Xuelian
Lu Ruijun
JJF1126—2004
(Tianjin Metrology Technology Research Institute)
(China National Institute of Metrology)
(Tianjin Institute of Metrology Technology)
(Times Group Corporation)
(Tianjin Institute of Metrology Technology)
References
Overview,
4 Metrological characteristics
4.1 Repeatability
Indication error
Indication error of curved wall thickness measurement
Fine-tuning range of thickness calibration
Indication error of thickness with variable sound velocity
Indication stability
Calibration conditions
6 Calibration items and calibration methods Method
Repeatability
Indication error
Indication error of curved wall thickness measurement,
Fine-tuning range of thickness calibration.
Indication error of thickness with varying sound velocity
6.6 Indication stability
Expression of calibration results
Recalibration time interval
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Contents of calibration certificate
Technical requirements for standard thickness blocks
Technical requirements for standard round pipes Technical requirements
JJF1126—2004
Uncertainty analysis of calibration results of indication error of ultrasonic thickness gauge Sound velocity and sound velocity ratio of various materials
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1 Scope
JJF1126—2004
Calibration specification of ultrasonic thickness gauge
This calibration specification is applicable to the calibration of ultrasonic thickness gauges with a resolution of 0.1mm and 0.01mm. References
This specification references the following documents:
JJF1001-1998 General metrological terms and definitions JJF1059—1999 Evaluation and expression of measurement uncertainty GB/T12064.1-1999 Nondestructive testing terms Ultrasonic testing GB/T11344—1989 Thickness measurement by contact ultrasonic pulse echo method When using this specification, attention should be paid to using the current valid versions of the above references. 3 Overview
Ultrasonic thickness gauges are mainly used to measure the wall thickness of ship hulls, oil and gas pipelines, high-pressure vessels, boilers, etc., as well as the thickness of large-area plates. The material to be measured can be a metal material represented by steel, or a non-metallic material such as plastic and nylon. The principle is that the instrument transmits ultrasonic waves through the probe, which are reflected back after reaching the bottom surface of the test piece and received by the measuring head. The time of ultrasonic wave propagation in the material is accurately measured by the counter, and the calculation is performed according to the following formula, and the measured value is displayed on the display (a)
1-Instrument housing: 2-Coupling indicator: 3-Thickness fine-tuning knob: 4-Protective cover: 5-Start button; 6-Illumination button: 7-Probe plug; 8-Display; 9-Probe (b)
1-Instrument housing: 2-Operation button; 3-Coupling indicator; 4-Display: 5-Probe plug; 6-Metric-inch conversion key; 7-Calibration thickness block; 8-Probe
Figure 1 Appearance of the instrument
Thickness value.
Where: H specimen thickness;
Sound velocity;
JJF1126-2004
-The propagation time of ultrasonic wave in the specimen. The instrument resolution is divided into 0.1mm and 0.01mm ultrasonic thickness gauges. The measurement range is generally 0.5mm~200mm, and the sound velocity range can vary from 1000m/s to 9999m/s (see Appendix E for the common sound velocity table of various materials). The appearance structure of common instruments is shown in Figure 1. 4 Metrological characteristics
4.1 Repeatability
The instrument resolution specifications and the corresponding repeatability requirements are shown in Table 1. 4.2 Indication error
The instrument resolution specifications and the corresponding maximum allowable indication error are shown in Table 1. Table 1
Resolution
Repeatability
Maximum allowable indication error
The lower limit of the measurement range is below 10mm
Note: H in the table is the nominal value of the standard thickness block. Indication error of curved wall thickness measurement
The instrument resolution specifications and the corresponding maximum allowable indication error are shown in Table 2. Table 2
Resolution
4.4 Fine-tuning range of thickness calibration
Specifications of standard round tubes
Outer diameter 440 Wall thickness 3
Outer diameter 430 Wall thickness 2
10mm to upper limit of measurement range
+(0.01 )）
Maximum allowable indication error
The instrument should meet the fine-tuning range of ±1mm (instruments without fine-tuning function do not need this calibration). 4.5 Thickness indication error of variable sound velocity
The indication error should not exceed ±0.50mm.
4.6 Indication stability
The instrument resolution specifications and corresponding indication stability requirements are shown in Table 3 (automatic shutdown instruments do not need this calibration).
Instrument resolution
JJF1126—2004
Indication stability/(mm/h)
Note: There is no conclusion on whether the calibration work is qualified or not, and the above metrological characteristics requirements are for reference only. 5 Calibration conditions
The temperature in the calibration room should be 20℃±5℃. The relative humidity should be less than 65%RH. 5.1bzxZ.net
5.2The standard thickness block and standard round tube used for the calibration instrument should meet the technical requirements of Appendix B and Appendix C. 5.3The calibration thickness block provided with the ultrasonic thickness gauge should meet the technical requirements of Appendix B. 6 Calibration items and calibration methods
Before calibration, it should be confirmed that there are no defects in appearance and electromechanical functions that may affect the calibration metrological characteristics. 6.1 Repeatability
After turning on the instrument, operate the sound velocity adjustment key or the sound velocity dial to adjust the sound velocity to 5900m/s, then return the instrument to the thickness measurement state, and apply the coupling agent to the center of the 5.5mm standard thickness block. Use the probe to measure the thickness block 5 times continuously, and take the difference between the maximum and minimum values ​​as the repeatability of the instrument. You can also directly use the random calibration thickness block of the instrument for this calibration.
6.2 Indication error
Calibrate according to the procedure specified by the instrument. Measure the standard thickness blocks in Appendix B one by one within the measuring range of the instrument, measure each block 3 times continuously, and take the average value as the indication of the instrument on the thickness block. When the same ultrasonic thickness gauge has two resolutions of 0.1mm and 0.01mm, the two indication errors should be calibrated separately. The indication error 8 is calculated as follows:
OH=HH
Where: H—average indication of the instrument;
H—nominal value of a standard thickness block.
6.3 Indication error of curved wall thickness measurement
The instrument is calibrated according to the procedure specified by the instrument (do not recalibrate if the probe is not replaced). According to the provisions of Table 2, measure the wall thickness of the standard circular tube corresponding to its resolution (see Appendix C for technical requirements). When measuring, make the sound insulation layer 1 of the probe parallel or perpendicular to the element line of the measured standard circular tube 2 (as shown in Figure 2), swing the probe slightly and observe the indication, take the smallest stable indication as the measured value, and the difference between the measured value and the nominal value of the wall thickness of the standard circular tube is the indication error. 6.4 Fine-tuning range of thickness calibration
After the instrument is calibrated, keep the coupling state between the probe and the thickness block unchanged, and continuously adjust the "△" and "√" keys of the instrument calibration (or rotate the fine-tuning knob for thickness calibration). The instrument indication change range should not be less than ±1mm. 6.5 Thickness indication error of changing sound velocity
JJF1126--2004
Figure 2 Schematic diagram of curved surface measurement
Set the sound velocity of the instrument at 3900m/s and 7900m/s respectively, measure the 10mm standard thickness block, measure 3 times at each sound velocity, and obtain the average value of the corresponding sound velocity. and H, according to the theoretical value of the converted thickness Hol = 6.61mm (3900m/s), Hcz2 = 13.39mm (7900m/s), calculate the indication error after the sound velocity is changed as follows: Om = Ho-Ho
Om = H-Ho2
Wherein: 8m——thickness indication error when the sound velocity is 3900m/s; 8m——thickness indication error when the sound velocity is 7900m/s. 6.6 Indication stability
Use the probe to measure any standard thickness block or the thickness block randomly calibrated by the instrument, record the first indication, and then repeat the measurement every 15min, observe continuously for 1h, and take the maximum difference between the indications as the indication stability. Expression of calibration results
After the instrument is calibrated, a calibration certificate shall be issued. The calibration certificate shall at least include the information contained in Appendix A. 8 Recalibration time interval
The recalibration time interval is recommended to be 1 year.
Appendix A
1. Title: Calibration Certificate;
2. Name and address of laboratory;
3. Location of calibration;
JJF1126—2004
Contents of calibration certificate
4. Certificate or report number, page number and total number of pages; 5. Name and address of the inspection unit;
6. Name of the instrument to be calibrated;
7. Manufacturer, model, specification and number of the instrument to be calibrated; 8. Measurement standard used for calibration Name and validity period; 9. Name, number of this specification and any deviation, addition or reduction from this specification; 10. Ambient temperature during calibration;
11. Calibration results of calibration items;
12. Measurement uncertainty of calibration results of indication error; 13. Signature of calibrator, verifier and approver; 14. Issuance date of calibration certificate;
15. Recommendation on revalidation time interval;
16. Calibration certificate may not be partially reproduced without written approval of calibration laboratory. Appendix B
JJF1126—2004
Technical requirements for standard thickness blocks
B.1 The nominal values ​​and allowable deviations are listed in Table B.1. Table B.1
Nominal value H
Allowable deviation.
Nominal value H
Allowable deviation.
Nominal value H
Allowable deviation.
Technical requirements for standard thickness blocks
*Special dimensions for calibrating the lower limit of measurement of various instruments. ±0.01
B.2 See Figure B.1 for geometric shape and dimension requirements (unit: mm). B.3 Material: 45 steel
Note: The H value in the table is a recommended value.
HI±.
Appendix C
JJF1126—2004
Technical requirements for standard round tubes
C.1 The nominal values ​​and allowable deviations are listed in Table C.1. Table c.1
Technical requirements for standard round tubes
Nominal value of wall thickness
Allowable deviation of wall thickness
2 (outer diameter 30)
C.2 Geometric shape and size requirements See Figure C.1 (unit: mm) C.3 Material: 45 steel
3 (outer diameter Φ40)
Appendix D
D.1 Measurement method
JJF1126—2004
Uncertainty analysis of calibration results of indication error of ultrasonic thickness gauge First calibrate the instrument, and then calibrate the instrument with a standard thickness block. The difference between the average measurement value H of the instrument and the nominal value H of the standard thickness block is the indication error. D.2 Mathematical model
Indication error formula:
In the formula: —
- Indication error of ultrasonic thickness gauge;
- Average measurement value of the instrument:
H - Standard thickness value of standard thickness block. D.3 Variance and sensitivity coefficient
According to u()=
In the formula:
u2（x） we get
u = u?(On)= C)(H)u(H) + C(H)u(H)o=
c(H)=$
C2(H)=
u=u(H)+u,(H)
D.4 Summary of standard uncertainty
Standard uncertainty
Measurement component
Source of uncertainty
Standard uncertainty/um
Dimension deviation of standard thickness block
When 10mm:
0.01×(1/3)=0.003=3
When 200mm:
0.05×(1/3)=0.017=17
Inspection of standard thickness block Fixed error
Measurement repeatability of calibration
D.5 Calculation of standard uncertainty components
0.003×(1/3)=0.001=1
0.025×1/3=14
D.5.1 Uncertainty component caused by size deviation of standard thickness block u Sensitivity
Ic:/.u./μm
When 10mm:
When 200mm:
Degrees of freedom
Calibration uses the nominal value of the standard thickness block. Although its size deviation is a comprehensive error, it is negligible at this time and should be regarded as an accidental error and should be processed according to the normal distribution 3. Range, so when 10mm:
=0.003mm=3um01
B.2 See Figure B.1 for geometric shape and size requirements (unit: mm). B.3 Material: 45 steel
Note: The H value in the table is a recommended value.
HI±.
Appendix C
JJF1126—2004
Technical requirements for standard round tubes
C.1 The nominal values ​​and allowable deviations are listed in Table C.1. Table c.1
Technical requirements for standard round tubes
Nominal value of wall thickness
Allowable deviation of wall thickness
2 (outer diameter 30)
C.2 Geometric shape and size requirements See Figure C.1 (unit: mm) C.3 Material: 45 steel
3 (outer diameter Φ40)
Appendix D
D.1 Measurement method
JJF1126—2004
Uncertainty analysis of calibration results of indication error of ultrasonic thickness gauge First calibrate the instrument, and then calibrate the instrument with a standard thickness block. The difference between the average measurement value H of the instrument and the nominal value H of the standard thickness block is the indication error. D.2 Mathematical model
Indication error formula:
In the formula: —
- Indication error of ultrasonic thickness gauge;
- Average measurement value of the instrument:
H - Standard thickness value of standard thickness block. D.3 Variance and sensitivity coefficient
According to u()=
In the formula:
u2（x） we get
u = u?(On)= C)(H)u(H) + C(H)u(H)o=
c(H)=$
C2(H)=
u=u(H)+u,(H)
D.4 Summary of standard uncertainty
Standard uncertainty
Measurement component
Source of uncertainty
Standard uncertainty/um
Dimension deviation of standard thickness block
When 10mm:
0.01×(1/3)=0.003=3
When 200mm:
0.05×(1/3)=0.017=17
Inspection of standard thickness block Fixed error
Measurement repeatability of calibration
D.5 Calculation of standard uncertainty components
0.003×(1/3)=0.001=1
0.025×1/3=14
D.5.1 Uncertainty component caused by size deviation of standard thickness block u Sensitivity
Ic:/.u./μm
When 10mm:
When 200mm:
Degrees of freedom
Calibration uses the nominal value of the standard thickness block. Although its size deviation is a comprehensive error, it is negligible at this time and should be regarded as an accidental error and should be processed according to the normal distribution 3. Range, so when 10mm:
=0.003mm=3um01
B.2 See Figure B.1 for geometric shape and size requirements (unit: mm). B.3 Material: 45 steel
Note: The H value in the table is a recommended value.
HI±.
Appendix C
JJF1126—2004
Technical requirements for standard round tubes
C.1 The nominal values ​​and allowable deviations are listed in Table C.1. Table c.1
Technical requirements for standard round tubes
Nominal value of wall thickness
Allowable deviation of wall thickness
2 (outer diameter 30)
C.2 Geometric shape and size requirements See Figure C.1 (unit: mm) C.3 Material: 45 steel
3 (outer diameter Φ40)
Appendix D
D.1 Measurement method
JJF1126—2004
Uncertainty analysis of calibration results of indication error of ultrasonic thickness gauge First calibrate the instrument, and then calibrate the instrument with a standard thickness block. The difference between the average measurement value H of the instrument and the nominal value H of the standard thickness block is the indication error. D.2 Mathematical model
Indication error formula:
In the formula: —
- Indication error of ultrasonic thickness gauge;
- Average measurement value of the instrument:
H - Standard thickness value of standard thickness block. D.3 Variance and sensitivity coefficient
According to u()=
In the formula:
u2（x） we get
u = u?(On)= C)(H)u(H) + C(H)u(H)o=
c(H)=$
C2(H)=
u=u(H)+u,(H)
D.4 Summary of standard uncertainty
Standard uncertainty
Measurement component
Source of uncertainty
Standard uncertainty/um
Dimension deviation of standard thickness block
When 10mm:
0.01×(1/3)=0.003=3
When 200mm:
0.05×(1/3)=0.017=17
Inspection of standard thickness block Fixed error
Measurement repeatability of calibration
D.5 Calculation of standard uncertainty components
0.003×(1/3)=0.001=1
0.025×1/3=14
D.5.1 Uncertainty component caused by size deviation of standard thickness block u Sensitivity
Ic:/.u./μm
When 10mm:
When 200mm:
Degrees of freedom
Calibration uses the nominal value of the standard thickness block. Although its size deviation is a comprehensive error, it is negligible at this time and should be regarded as an accidental error and should be processed according to the normal distribution 3. Range, so when 10mm:
=0.003mm=3um
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