Factor A in Asme section ii , thk for External Pressure
Factor A in Asme section ii , thk for External Pressure
(OP)
Hi
i could not extract factor A from tabluar values figure G
Material from table HA-1
D/T=69.7
L/D=50
1-A=?
2- if there is not same D/L according to L/D how shall be do , forexample in above there are 50 in L/D 60 and also 80
Ex: D/t=20 , L/D=40 A=0.275-02
D/t=22 , L/D=40 Whats A ?
D/t=25 , L/D=40 Not in Table
i could not extract factor A from tabluar values figure G
Material from table HA-1
D/T=69.7
L/D=50
1-A=?
2- if there is not same D/L according to L/D how shall be do , forexample in above there are 50 in L/D 60 and also 80
Ex: D/t=20 , L/D=40 A=0.275-02
D/t=22 , L/D=40 Whats A ?
D/t=25 , L/D=40 Not in Table
RE: Factor A in Asme section ii , thk for External Pressure
Often more convenient to just pick the values off of Fig. G if a "high degree" of accuracy is not needed.
For your first example, Do/t at L/Do = 50 is about 70, A is about halfway between 0.00015 and 0.0003, roughly 0.00023. A reasonably good clear platic scale is useful here.
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Factor A in Asme section ii , thk for External Pressure
If you want a more exact value you will have to interpolate between the ones listed in Table G. Given that Figure G is clearly log-log, you should consider using log-log interpolation for the most accurate value of A.
RE: Factor A in Asme section ii , thk for External Pressure
Dot = 69.7
LDo = 50
A = 0.0002410
I use an excel formula to index the tables I have in excel, then interpolate.
RE: Factor A in Asme section ii , thk for External Pressure
linear 0.23 or 0.24 ? and if log-log interpolate be accurate so what is the final result ? in somewhere i saw cal for 69.7 & 50 >>> 0.25-03
RE: Factor A in Asme section ii , thk for External Pressure
RE: Factor A in Asme section ii , thk for External Pressure
Example for first row (natural logs):
Do/T = 500, (log=6.2146), L/Do = 0.231 (log=-1.46534):
log(A) = -0.4385-(-1.46534+1.60944)/(-0.91629+1.60944)*(-0.4385+1.19733) = -0.59625
This would give (excluding the factor 10^-3) A=exp(-0.59625)=0.551 , quite different wrt the linear interpolation.
please define whats 1.19733 in above Eq ( is there mistake ??? - should be 1.1874 instead it or this is right in Eq)
D/t = 500
L/D 0.2 0.4
factor A 0.231 ?
factor A 0.645 0.305
RE: Factor A in Asme section ii , thk for External Pressure
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Factor A in Asme section ii , thk for External Pressure
- Interpolate on the Do/T line above to get the value of A above at your L/Do.
- Interpolate on the Do/T line below to get the value of A below at your L/Do.
- Interpolate between these two A values to get A final at your actual Do/T.
This is just one way of getting there. DO NOT just blindly follow my sequence. Think about it and convince yourself this is proper.RE: Factor A in Asme section ii , thk for External Pressure
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Factor A in Asme section ii , thk for External Pressure
in tabular values figur G section ii
60 80
0.306 0.172
Factor A General interpolation =0.24101-03
Factor A with exp(use ln in linear interpolation ) = 0.2267-03
Now which ones to be used ?
RE: Factor A in Asme section ii , thk for External Pressure
this one: Factor A General interpolation =0.24101-03
RE: Factor A in Asme section ii , thk for External Pressure
Ref UG-28 (c)(1), Step 4: It's your choice
EDIT: I recommend you perform the calculations using both values and observe if the difference is worth worrying about or not.
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Factor A in Asme section ii , thk for External Pressure
is Factor B in 750 F or 400 C degree
2750psi or 2903 psi ... i am afraid of wrong calculation manual
RE: Factor A in Asme section ii , thk for External Pressure
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Factor A in Asme section ii , thk for External Pressure
this linear interpolation is helpful for such type of issues.
RE: Factor A in Asme section ii , thk for External Pressure