durometer readings on rubber lined pipe
durometer readings on rubber lined pipe
(OP)
Can anyone tell me how accurate are durometer readings on rubber lined pipe ?
According to ASTM D2240, durometer hardness test should be performed on FLAT and parallel surfaces "to permit the presser foot to contact the specimen over an area of at least 6 mm (0.24") from the indentor point". All pipe surfaces are curved.
Even for 24" pipe, the curvature still mean that there is 0.0026" between the high and low points within an area of 0.24" radius. Will this cause an error in the durometer reading ?
If this curvature is not significant to cause a problem, what is the minimum pipe size that a durometer reading will yield an accurate result ?
If the surface must be perfectly flat, then how do we perform a QA check on the hardness of rubber lining in a pipe ?
According to ASTM D2240, durometer hardness test should be performed on FLAT and parallel surfaces "to permit the presser foot to contact the specimen over an area of at least 6 mm (0.24") from the indentor point". All pipe surfaces are curved.
Even for 24" pipe, the curvature still mean that there is 0.0026" between the high and low points within an area of 0.24" radius. Will this cause an error in the durometer reading ?
If this curvature is not significant to cause a problem, what is the minimum pipe size that a durometer reading will yield an accurate result ?
If the surface must be perfectly flat, then how do we perform a QA check on the hardness of rubber lining in a pipe ?





RE: durometer readings on rubber lined pipe
RE: durometer readings on rubber lined pipe
Unless your coating is 0.25 inches thick, the influence of the substrate will significantly affect the results of the test, as well as the radius of curvature of the test specimen.
The best way that I know of to take measurements on a pipe coating is the remove the coating from the pipe, and layer sections of the coating on a flat surface until the appropriate minimum thickness is attained, then take your measurements. If the coating is not relatively smooth on both sides, the sample may need to be "skived" to remove the gross surface imperfections prior to layering.
Hope this helps.
Rich Geoffroy
Polymer Services Group
polyserv@cox.net