UT pipe Tm Correction 1

[Rjeffery]

I have been unsuccessful in finding a formula for correcting (reducing) wall thickness readings of carbon steel pipe, taken using UT pulse-echo, when the pipe is over ambient temperature. The best I can come up with is the “Reduce by 1% for every 100 degree (F) rise above 70 degrees” rule of thumb. Most of what I find deals with expansion along its length... I would be pleased if someone could point me in the right direction.

Thank you.

 

[BigInch]

Using the information I found here,

http://en.wikipedia.org/wiki/Speed_of_sound

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe2.html

and for E and linear expansion on the engineeringtoolbox site,
Temp 100F 200F
alpha 7.7E-6 8.4E-6 in/in/F
volumetric expansion = 3 * linear alpha
density for steel 490 pcf @ 60F
calculated density for steel at 200 F thus = 489.987 pcf

using,
E for carbon steel at 100F = 29.5 ksi
E for carbon steel at 200F = 28.8 ksi

replacing E with M when lateral dimensions are high in relation to wavelength M = E * (1-v)/(1-v-2*v^2)
increases Young's Modulii by about 1.346

then wavespeed = (M/den)^0.5
wavespeed at 100F = 19,357 fps
wavespeed at 200F = 19,126 fps
change in wavespeed/100F = 230.8 fps
% change in wavespeed per 100F = 230.8/19357 * 100

Actually I get about 1.19%/100F

http://virtualpipeline.spaces.msn.com

"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein