sa-333 impacts 1

[Mikeqc1]

if the the impact sample is subsize, and less than 80% of actual wall thk a reduction in temp is needed my quaestion is
Would the nominal wall be used for the calc or can the wall be measured.
If i use the nominal it less than 80% if i use the low end of the wall thickness its within.(is that stretching the intent of the code?)
But how do i know if the impact sample was at the right temp if i dont know what the pipe wall was measured.
Or do i use the sch nominal thickness.
Im not confident aBOUT THIS MANUFACTURER.
mdk

 

[metengr]

The reason for the reduction in test temperature is that the Charpy impact test relies on impact specimens that are full thickness (10mm), not the thickness of the pipe or plate. If the impact specimens are subsize, the impact results will be higher because of lack of restraint in the test specimen.

This has nothing to do with nominal versus actual wall of the pipe. If the impact specimens cannot be machined to full size, they must be considered subsize and temperature reduction is required to compensate.

 

[Mikeqc1]

The reason for subsize samples is the lack of material in the pipe wall to aquire a full size.If the wall thickness say .375 cannot produce the proper amount of material for full size (.394) the ASME Code allows subsizes. If the subsize is 80% or Greater than the actual wall thickness no reduction in temperature is necessary, but if it is lower than 80% the temperature must be reduced by a calutation.
the reason i imagine is to cbetter represent the material properties.
Am i wrong in my application of SA-333

 

[Mikeqc1]

from memory.....
5" xxs
SA-333 seamless pipe
Impact size is .394 x .295
the temp was -45c
as i was reviewing my MTRs i noticed this.
i think the temp of these impact temps should have been -48c
Now from the same manufacturer i got another load of 4" pipe wall .281 with the same heat#

the 4" pipe had .394x.295 but the wall thickness is only .281?
I dont feel good about this pipe.
What do you think

 

[Mikeqc1]

iwish i could spend a fewe months in a destructive lab

 

[metengr]

Ok, It is the actual wall thickness measured in accordance with SA 333 , Section 14.1.2.

 

[Mikeqc1]

so i cannot reject this lot based on the no reduction in this case one could say it was not needed, based on the measured wall at lab.
if the wall measured at the low end of the spec it would have been above the 80% but no one knows what the measured piece was to begin with.
Do you see my delema? Would any even atempt to question it, but most of all are the MTRs correct.

 

[Mikeqc1]

So the definition of actual in this case is measured thickness (not Nominal wall thk) and since that dimention is not reported i would not have a leg to stand on by saying the sample size is less than 80%.
look at this cert at the charpy size. I will speak with the AI on this, but i like to fully review and question everything before i consult the AI.
I seems strange that the MTR doesnt give all the infomation to veriy results and method.

 

[Mikeqc1]

the impact results will be higher because of lack of restraint in the test specimen


Sir could you give more detail on this?

 

[SJones]

You could start here

thread330-67956

and then move on to a search using both the terms "plane strain" and "Charpy"

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04