Thickness measurement issues with thickness gauges
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When measuring the thickness of equipment and pipes, since the thickness gauges we had were a bit larger in size, we used the thickness gauges provided by the factory. However, upon returning, we found that the values obtained using their specified sound speeds for carbon steel and stainless steel were higher than the wall thickness values indicated on the drawings. Is it possible to divide these values by a certain coefficient to correct them? For the first device and the first set of data, we measured it using two thickness gauges: the actual wall thickness of the device was 5 mm, while our measurements showed 4.76 mm; the readings from those other gauges were 5.30 mm. I suspect that the experienced worker in the factory might, due to not using those sound speed values for a long time, get them wrong, which leads to inaccurate measurements. Can the values be corrected based on the known conditions, using those inaccurate values as a starting point? Is this feasible? Since all the equipment and pipes are insulated, it’s not very practical to take new measurements? Last edited by Drifting in the north on 2008-12-16 10:02]
Friends with experience in this area please offer some advice or feasible solutions.
Prepare corresponding test blocks based on the material under test, and adjust the corresponding sound speed.
The first time, I used two thickness gauges to measure the same point, obtaining two values: 4.76 (for mine) and 5.30 (for the other one). It was only later that I realized my reading was accurate while the other one had an error (probably due to an incorrect sound speed setting). However, many subsequent measurements were taken using the other gauge. Can I use 4.76 divided by 5.30 to get a coefficient, and then multiply the similarly obtained values by this coefficient? I wonder if I made myself clear this time?
It’s better to calibrate using standard test blocks... Using a coefficient may not yield accurate results
It can be converted.. The value adjusted by the original poster should be a frequency value, not an acoustic speed value (acoustic speed in a medium = frequency * wavelength)
It should be possible, but the reliability of the coefficient obtained from just one data point is low; it’s better to have data from three or more points, and then use the arithmetic mean method to determine the corresponding coefficient, which yields more accurate results. For reference!
Re-measure the sample blocks; it’s possible to make conversions, but you should keep the thickness gauge in its original state. It’s best to adjust it properly before going to the site for measurement
Well, that’s what I’ll do. The best approach is to take another measurement. Is there any type of thickness gauge that can determine the thickness of any material simply by applying a coupling agent, without the need to adjust the sound speed specific to each material?
A thickness gauge can be used to measure standard test blocks, and the results obtained can be used to adjust the values you initially measured.