CTOD test on 5D Bends.
CTOD test on 5D Bends.
(OP)
For sub sea pipeline usually CTOD test is carried out for both pipeline and 5D bend used in the pipeline.Can any body suggest the exact reason of doing CTOD( Crack Tip Opening Displacment)test. Because for piping under ASME B 31.3 piping this test is generally not suggested by any consultant.





RE: CTOD test on 5D Bends.
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: CTOD test on 5D Bends.
RE: CTOD test on 5D Bends.
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: CTOD test on 5D Bends.
RE: CTOD test on 5D Bends.
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: CTOD test on 5D Bends.
The charpy test is a better (as well as faster and less expensive) test when the upper shelf material toughness is less than 100J. (Some might put this in the 100J to 200J range) Below 100J, the charpy test is a high strain test and indicates toughness pretty well. Particularly as one should also have pre-bend charpy data to compare to.
When pre-bend toughness is over 100J, charpy energy may be miss leading if too much of the hammer energy is being consumed by crack initation. In that case, the test is not measuring toughness against high strain rate and may result in a miss-leading high toughness value. Even so, a high charpy energy value is still pretty good and acceptable for many applications. Charpy is still the most commonly used standard.
In my opinion, CTOD should be reserved for critical applications where technology is being stretched in one way or another. Standard applications that have been done many times before should stick with charpy.
RE: CTOD test on 5D Bends.
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/