NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Real World Measurement in a Nuclear Plant

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 A Corporate Lab’s View of Process Measurement Plant personnel are free to ask the laboratory for measurement advice. Plant personnel are free to ask the laboratory for measurement advice. Standards / M&TE Calibration Lab Salem Hope Creek

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Traceability (The Traditional View) NMI Approved Suppliers Intrinsic Standards Primary Lab Standards Working Lab Standards M&TE

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Traceability (The Bigger Picture) Realization of the SI through an NMI Approved Suppliers Primary Lab Standards Working Lab Standards M&TE Your Plant or End User Here

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 The End Users In order to get the quality OUT that your lab puts in, your end users: In order to get the quality OUT that your lab puts in, your end users: Need to understand the equipment and the uncertainties associated with using it.Need to understand the equipment and the uncertainties associated with using it. Need to study measurement.Need to study measurement. Need to be metrologists!Need to be metrologists!

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Real World Metrology Four Short Stories Four Short Stories Dimensional measurement in varying environments.Dimensional measurement in varying environments. Differential pressures in high static pressures.Differential pressures in high static pressures. Very low differential pressure.Very low differential pressure. Non-invasive volumetric liquid flow measurement.Non-invasive volumetric liquid flow measurement.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Story number one Dimensional measurement in varying environments End users would like to measure bearings that are about 6” in diameter, and they need to know the value to within +/ ”. These measurements will be done in the field and the temperature could be between 65 and 90 degrees F.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Dimensional measurement in varying environments Clearly there is an effect due to thermal expansion, but … 1. Can we predict it accurately? 2. Can we know the uncertainty?

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Dimensional measurement in varying environments What factors are critical to this process? What factors are critical to this process? The type of metalThe type of metal The coefficient of thermal expansionThe coefficient of thermal expansion The accuracy of the temperature measurementThe accuracy of the temperature measurement

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Depending on the table and the steel, the TCE values can vary from 9.9 to 17.3ppm/°K, but most people accept a number around 11.5±0.5ppm/°K to be typical for most forms of steel. Depending on the table and the steel, the TCE values can vary from 9.9 to 17.3ppm/°K, but most people accept a number around 11.5±0.5ppm/°K to be typical for most forms of steel. But low and behold, the metal was not steel. It was “Babbitt metal”. But low and behold, the metal was not steel. It was “Babbitt metal”. Dimensional measurement in varying environments

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Babbitt metal: Babbitt metal: anti-friction metal first produced by Charles Babbitt in 1839.anti-friction metal first produced by Charles Babbitt in Usually over 90% Tin and about 5% Antimony, but there may also be Copper, Zinc, and Lead.Usually over 90% Tin and about 5% Antimony, but there may also be Copper, Zinc, and Lead. Typical TCE is about 1.5 to 2 times that of Steel.Typical TCE is about 1.5 to 2 times that of Steel. Based on this we used Steel’s TCE of 11.5ppm/°K±0.5ppm/°K, times 1.75±0.25 which results in 20.1ppm/°K ±3.6ppm.Based on this we used Steel’s TCE of 11.5ppm/°K±0.5ppm/°K, times 1.75±0.25 which results in 20.1ppm/°K ±3.6ppm. Dimensional measurement in varying environments

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Nominal inside diameter: 6” Nominal inside diameter: 6” TCE: ~20.1ppm/°K TCE: ~20.1ppm/°K ΔT: 12.2°K ΔT: 12.2°K Therefore the expected change due to thermal expansion will be 1471µ inches ±???µ inches Therefore the expected change due to thermal expansion will be 1471µ inches ±???µ inches Dimensional measurement in varying environments

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Then the technician asked a classic question: “What is the relative effect of thermal expansion on the inside diameter?” Then the technician asked a classic question: “What is the relative effect of thermal expansion on the inside diameter?” The easiest way to explain this to a mechanical technician is: The easiest way to explain this to a mechanical technician is: Assumption: The Metal is Isotropic Assumption: The Metal is Isotropic Given: The outer Diameter of the sleeve will expand in a linear manner consistent with the linear TCE of the metal. Given: The outer Diameter of the sleeve will expand in a linear manner consistent with the linear TCE of the metal. Given: The wall thickness will expand in a linear manner consistent with the linear TCE of the metal. Given: The wall thickness will expand in a linear manner consistent with the linear TCE of the metal. Therefore the space between the walls must expand at the same rate as the rest of the material. Therefore the space between the walls must expand at the same rate as the rest of the material. Therefore the inside diameter must expand at the same rate Therefore the inside diameter must expand at the same rate Dimensional measurement in varying environments

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Dimensional measurement in varying environments

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 The Thermal Coefficients are not well defined for most dimensional M&TE. The Thermal Coefficients are not well defined for most dimensional M&TE. inside micrometer?inside micrometer? telescoping gage?telescoping gage? Tri point micrometer or “Intramic”?Tri point micrometer or “Intramic”? Dimensional measurement in varying environments

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Dimensional measurement in varying environments The technician decided to use a telescoping gage that was acclimated to about 68° and make the measurement quickly. He brought the gage back to his shop where he measured it with an outside micrometer capable of measuring ±0.0001”. This process was repeated three times, to ensure repeatability and roundness

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Dimensional measurement in varying environments So what was his overall uncertainty in the field? Type A: Outside Micrometer ±100µ”Type A: Outside Micrometer ±100µ” Type B: Thermal Expansion ±213µ”Type B: Thermal Expansion ±213µ” Result: ±235µ”. Result: ±235µ”. Although this did not make the original specification of 100µ”, it was the best that could be done without investing a great deal more time and resources.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Dimensional measurement in varying environments Real World Measurement? Real World Measurement? The uncertainty calculation is based on questionable sources (TCE of Babbitt Metal and steel?) The uncertainty calculation is based on questionable sources (TCE of Babbitt Metal and steel?) We were unable to make our measurement uncertainty goal. The end user was likely to underestimate his uncertainty without intervention. We were unable to make our measurement uncertainty goal. The end user was likely to underestimate his uncertainty without intervention.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Dimensional measurement in varying environments So what was his overall uncertainty in the field? Type A: Outside Micrometer ±100µ” Type A: Outside Micrometer ±100µ” Type B: Thermal Expansion ±213µ” Type B: Thermal Expansion ±213µ” Result: ±235µ”. Although this did not make the original specification of 100µ”, it was the best that could be done without investing a great deal more time and resources.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Differential pressures in high static pressures.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Differential pressures in high static pressures. Required accuracy: ±0.1% of the DP readingRequired accuracy: ±0.1% of the DP reading Range of DP measurements: 50 to 150 PSIDRange of DP measurements: 50 to 150 PSID Typical high side static pressure: 900 to 1000 PSIGTypical high side static pressure: 900 to 1000 PSIG

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Differential pressures in high static pressures. And to complicate things the pump that is being tested : Is in a radiologically contaminated area.Is in a radiologically contaminated area. Creates pulsations in the flow, so some sort of averaging must be done!Creates pulsations in the flow, so some sort of averaging must be done!

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Differential pressures in high static pressures. How it has been done for the past 30 years: How it has been done for the past 30 years: Use a rugged DP transmitter with a 1 to 5V output and high resolution meters. Repeat the test 10 times and calculate the average.Use a rugged DP transmitter with a 1 to 5V output and high resolution meters. Repeat the test 10 times and calculate the average. Before and after the test, characterize the system using a dead weight tester.Before and after the test, characterize the system using a dead weight tester. Establish the correlation between volts on the meter and differential pressure.Establish the correlation between volts on the meter and differential pressure.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Differential pressures in high static pressures. Can this be improved? Can this be improved? Consider using two pressure gauges that are ±0.1% of readingConsider using two pressure gauges that are ±0.1% of reading Low side pressure 800 PSIG (±0.8 PSI)Low side pressure 800 PSIG (±0.8 PSI) High side pressure 900 PSIG (±0.9PSI)High side pressure 900 PSIG (±0.9PSI) Result 100 PSID ±1.2PSIDResult 100 PSID ±1.2PSID Or 1.2% of the resulting PSID!Or 1.2% of the resulting PSID!

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Differential pressures in high static pressures. Can this be improved? Can this be improved? It would seem that the answer is NOIt would seem that the answer is NO Only by taking secondary calibration standards into a hazardous environment could this be performed with better results.Only by taking secondary calibration standards into a hazardous environment could this be performed with better results. Pressure measurement accuracy of 0.01% would net an overall accuracy of 0.12% of DP reading.Pressure measurement accuracy of 0.01% would net an overall accuracy of 0.12% of DP reading.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Low Differential Pressures

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Low Differential Pressures Control rooms and other critical areas must maintain positive pressure.Control rooms and other critical areas must maintain positive pressure. This must be validated on a regular basis.This must be validated on a regular basis. If the measurements are close to the limit, increased accuracy may be needed.If the measurements are close to the limit, increased accuracy may be needed. One example was a test for 1.215”H2O ±0.003One example was a test for 1.215”H2O ±0.003

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Low Differential Pressures Liquid manometers had been used for years.Liquid manometers had been used for years. As equipment improved, so did the need for more accurate measurements.As equipment improved, so did the need for more accurate measurements. Digital differential pressure gauges (±0.06% FS) replaced manometers over the last 15 years.Digital differential pressure gauges (±0.06% FS) replaced manometers over the last 15 years. BUT, as the rated accuracy of the digital gauges increased, so did their failure rate.BUT, as the rated accuracy of the digital gauges increased, so did their failure rate.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Low Differential Pressures Plan: Analyze the requirements and reduce the gauge specification to 0.25% of range whenever feasible.Plan: Analyze the requirements and reduce the gauge specification to 0.25% of range whenever feasible. Result: 26 of 28 tests we able to use the reduced specification.Result: 26 of 28 tests we able to use the reduced specification. The remaining two test are performed by having the gauges calibrated immediately before and after the test.The remaining two test are performed by having the gauges calibrated immediately before and after the test.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Summary

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Summary The work that we all do as metrologists can be wasted without our strong involvement with the customers needs. The work that we all do as metrologists can be wasted without our strong involvement with the customers needs.

NCSL INTERNATIONAL SERVING THE WORLD OF MEASUREMENT SINCE 1961 Traceability in Industrial Processes fin Peter N. Buzzard Vice President of Industrial Programs, NCSLI Salem and Hope Creek Nuclear Stations PSEG Metrology Laboratory