B31.3 Questions - Somewhat Random 1

[ChEMatt]

Working through my understanding of the code, so there's a few random questions here. Thanks in advance for your help. (I'm using B31.3-2012.)

[ol 1]
[li]Do you bother to calculate Y when t < D/6, or do you just use Table 304.1.1?[/li]
[li]When solving for P using equation 3a or 3b, does that confirm that the pipe in question can withstand a 1.5x pressure test? (Assuming we're not working with extreme temperatures here.) If not, what are some examples, other than temperature effects, that would cause a pipe (and ONLY pipe) to not be able to withstand a 1.5x pressure test based on the MAOP calculated by equation 3a/3b?[/li]
[li]When solving equation 24 in 345.4.2b, for a pipe where the component design temperature is equal to the test temperature, does S = ST? (The question behind the question is, am I choosing the right values out of Table A-1?)[/li]
[li]To determine the yield stress of a given pipe, you simply substitute the Specified Minimum Yield Strength value from Table A-1 and solve for P, correct?[/li]
[/ol]

I think that's all I have for the moment.

Thanks again.

-Matt

 

[LittleInch]

Pretty random alright and not sure why you don't just read the code, but here goes.

1) Like it says in 304.1.1., fot T/D<6 use the table, for the T/D >= 6 calculate it
2) Yes,
3) Yes
4) To determine the yield stress of the pipe look at the SMYS figure provided. I think you mean pressure at which SMYS arrives at -
I think the answer is YES

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[ChEMatt]

Thank you for responding!

Sorry for not responding earlier. Took a couple weeks off after setting up the pressure test for the pipe in question.

I did read the code! I didn't understand it fully, which is why I'm here. Work stress can sometimes mess with ya. <grin>

Thanks again.

 

[Duwe6]

Point of Fact on piping calc's; Pressure T_min - 'Tee min' gives a ridiculously thin line that cannot even support its own weight when horizontal, as long as the MAWP is under 250 psi [centrifugal pumps usually cannot exceed 85 psi]. I prefer to eschew the calculation, and use the thickness from the Sch10 pipe chart, minus the 12.5% under-run wall thickness allowance. This will give a pipe that can hold itself up, usually on a 'usual & customary' 20-foot pipe rack span [beware 2.5"NPS and smaller], and still has a little Corrosion Allowance left before it fails structurally.