UG-101 max tensile range

[pvhd]

thread794-171746

I must perform a burst test using SA516-70 material on a cylindrical vessel and need confirmation of this old thread that the vessel will need to have samples of material removed and tested after burst test in order to obtain the "maximum tensile strength of range of specification at room temperature" per UG-101(m)(2)(a). This is an alternative calculation but I cannot evaluate its potential use without fully understanding the source of the information.
Thank you for your help.

 

[jharris3]

pvhd,

the old thread is correct but incomplete for your needs.

UG-101(j) describes how the yield or tensile properties are to be determined.

ASTM E8 is to be used with UG-101(j)(2).

It doesn't matter whether the burst method or the yield method is used, UG-101(j) applies and specimens are cut from the tested vessel. UNLESS the alternative methods written for each type of test (l) (m) or (o) are used. Sometimes there aren't any alternative methods written there...

Basically, the tensile test is to either
a) establish that the specimen is within the range specified for the material (ie between Uts min and Uts max found in Sec II part A) and then one would use "maximum tensile strength of range of specification at room temperature" or in the case of 516-70 the value would be 90ksi.

b) establish the average of the specimens when you don't have a range specified in Sec II part A (ie only a Uts min is given) then you would use that number as "average actual tensile strength of test specimens at room temperature"

It would be better of course to use the minimum of the two when Sec II part A gives a range for the material but it doesn't seem at first glance that the Code requires you to do that.

After all is said and done what UG-101 is doing is allowing you to certify a new vessel design for a pressure when it has parts or an overall design that can't be calculated by Code equations such as if the vessel had some very odd shape in the shells and/or heads, nozzles etc. that was not a simple cylinder, cone, dome, or flat plate. Then the method is to apply ~ 4:1 safety factor (for destructive burst tests) to the known ultimate strength (Uts min) of the material of construction.

-james

 

[fittingguy]

UG-101 (j) (2) provides the option of cutting samples from the actual burst part to determine tensile or yield values (provided that the samples are not affected by the burst test and not cut by torch from the sample which can affect temper). UG-101 (j) (2) also provides for alternative methods of determining tensile value as per (m).

In (m), if Sur per BPV Section II, Part D does not have range, then Suavg may be used, which is the actual average tensile value of the test specimen. In this case, can a mill certification be used for this Suavg value, if it is available on the mill certification for that material and Sur is not available?