(yeld strenght) wall thickness calculation acc ASME B31.1

[yacird]

Hi!
I would like to ask you, about value of yeld strenght.
Code ASME B31.8
material API 5L X60
Design Temperature 110stC
New pipe,

I know that acc ASME B31.1 the max. yeld strenght(S) is depends on temperature.
But please tell me what value of S I should be used acc ASME B31.8.
for API 5L X60 the value of S is 60000psi, but what value i can use in calculation formula?

and the second question. that corrosion allowance is included in design factor incuted in table 841.114A?

Sorry for my grammar, but English is not my native.

 

[yacird]

a little change,

in title of topic shall be 31.8
and this is code by witch i ask,
and the second, ASME B31.3 should be change on ASME B31.3

one more time

Hi!
I would like to ask you, about value of yeld strenght.
Code ASME B31.8
material API 5L X60
Design Temperature 110stC
New pipe,

I know that acc ASME B31.3 the max. yeld strenght(S) is depends on temperature.
But please tell me what value of S I should be used acc ASME B31.8.
for API 5L X60 the value of S is 60000psi, but what value i can use in calculation formula?

and the second question. that corrosion allowance is included in design factor incuted in table 841.114A?

Sorry for my grammar, but English is not my native.

 

[rneill]

B31.3 provides a table of allowable stress vs. temperature (Table A-1) and you would use this table to see what the basic allowable stress to be used in your calculation was. Refer to the Equations in Para.304.1.2.

B31.8 does not provide such a table. instead they provide a temperature derating factor. This factor is provided in Table 841.116A. Please refer to the Equation in Para 841.11(a). You take S (the specified minimum yield strength, SMYS) which equals 60,000 psi and you multiply this by the joint factor (E), by the design factor (F), and by the temperature factor (T).

The Factor F in B31.8 does not include the corrosion allowance - how could it - they don't know what corrosion allowance you want to use. You would calculate the pressure design thickness (the minimum thickness required based on pressure) and then you would add corrosion allowance.

 

[yacird]

Thank you for your answer, now i understand.

but, if i wanted use threaded pipe? Does I must add to my nominal calculated wall thickness depth of threaded acc ASME B1.20.1? or not it is needed?
Maybe I can not count threaded pipes according to ASME B31.8

 

[rneill]

If you look at B31.8 Code Interpretation 10-10 ...

Question: In para 841.11 should the nominal wall thickness be reduced by the nominal thread depth (dimension h of ASME B1.20.1, or equivalent)?

Answer: Yes.

Once you calculate the required thickness for pressure containment, you must add both corrosion allowance and thread depth to determine the minimum thickness of pipe that is required. The nominal wall thickness specified in ASME B36.10 must be greater than this minimum.