UG-101(m) Su E vs. Su avg vs. Su r 1

[bayardwv]

Here's my scenario....I have a SMALL (less than 4" dia) NON-Code Pressure Vessel that needs to have it's CRN renewed. Quebec has told me we have to do a new proof test and I've never done this before. The previous Proof test was performed by an outside manufacturing company and the documents they've supplied don't seem to include everything UG-101(m) requires.

Are my interpretations below correct?

Su is min tensile strength listed in Sect. II-D, Table 1A?

Su avg has to be determined by actually performing tensile tests on the parts 9or parts from the same heat) being tested, and if that's correct how many tests need to be done on a single piece? For some a reason I don't remember i think it's 3. (This is what I'm hoping to avoid if possible)

Su r = max tensile strength of range of specification at room temperature. Is this the Maximum Tensile Strength listed on the Material Cert?

Can I use a generic cert for a standard part, or must I use a cert that is tied to the actual part being tested?

 

[TGS4]

You need to use the certs specific to the vessel being tested. That's the point of correlating the minimum-specified material properties to the actual as-tested material properties.

 

[bayardwv]

TGS4,

Thank you, again. I appreciate that you respond to quickly to my inquiries.

Can you clarify that I am correct that my interpretation of "Su r" is found on the Material Test Report?
That I can then perform the MAWP calc in UG-101(m)(2) using SuE/Su r, and that becuae I am not using SuE/Su avg, no tensile tests are not required?

I'm not a metallurgist, but If I end up doing tensile testing on a part shouldn't the test results be similar to the MTR?

 

[Don56]

Sur is found in the material specification. Take SA-516 Gr 70 for example. The minimum tensile strength is 70 KSI the maximum tensile is 90 KSI. 90 KSI is the Sur, 70 KSI is the Su.

 

[bayardwv]

Yes but the material specification (Sect.II I assume) for s/s doesn't have a range, so can I use the Material Cert rating?

 

[TGS4]

Don56 is correct. Sur is the maximum of the specification (from Sec II, Part A), Su is the minimum of the specification (again from Sec II, Part A), both at tin temperature. Su_avg is the actual (from the mill certs) average value of the tensile stress. And then you would de-rate the pressure for elevated temperatures per UG-101(k).

What's your material spec?

Note that the equation in UG-101(m)(2)(-a) is an either/or, so you are permitted to use actual values from the mill cert.

 

[bayardwv]

TGS4,

THANK YOU!!!!! That's what I've needed all along, a clear definition of where the values for Su_r and Su_avg came from. Yes I understand the formulas in UG-101(m)(-a) are either/or.

My materials are SA240-316 (Min Tensile-75ksi), SA351-CF3M and SA351-CF3 (Min Tensile for both-70ksi).

Sect.II-A Tensile Tables for Stainless do not address the MAX, only the MIN Tensile ratings.

Therefore I do not have a value I can attach to Su_r so I'll have to use the formula w/ Su_avg. Do you agree?

 

[TGS4]

I agree.

 

[bayardwv]

Okay, here I go again...
Su_avg requires a minimum of 3 tensile test to obtain the average. Does that mean the mill performed 3 tensile tests and the result is whats on the MTR?

Another problem I'm having is that this is a LEGACY NON-CODE product with decades of use.
The parts purchased to make the final assembly require material cert's, however because it's a non-code product we haven't required the mat'l to be mark for traceabiltiy. Each order is received by a PO# which is received with an associative batch number. The MTR's are then labeled with the PO#, Batch# and the part#. My Problem is that having these MTR's won't do me any good because I can not match a part out of stock to a particular MTR.
Can I use a Representative MTR to Proof Test a Non-ASME Stamped product?

 

[Don56]

Unless there are 3 reported tests on the MTR, then the mill just performed 1 test. It is not an average. It is an actual test result. If you need an average of three tests you will need to perform 2 additional tests.... if you can tie the material to a test report. If you can not tie it to a test report you could perform 3 mechanical tests and chemical analysis of a piece of material and any other tests that are required by the specification to recertify it per UG-10. Good luck!