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Sriram_be
[h=Torispherical Head Thickness Calculation problem, pls help me]2[/h]
Vessel ID: 2100 mm
Length (T/T): 3900 mm
Thickness: 6 mm (considered)
Vessel Type: Horizontal Cylindrical with Torispherical Dish End
I manually calculate this
Inside Crown Radius of the Torispherical is ( L ): 2112 (OD of the Vessel) &
Inside Knuckle Radius is ( r ) 126.72 (6% of Inside Crown Radius),
As per ASME Sec VIII Div – 1 UG 32 (e)
The condition ts/L ≥ 0.002 is satisfied
And the formula for the thickness calculation is tp = 0.885 P L / S E − 0.1P
-------------------------------------------
But as per ASME Sec VIII Div – 1 Appendix – (1- 4)
The same condition is ts/L ≥ 0.002
The L/r ratio is involves ……….
L /r ratio is inside crown radius to the inside knuckle radius, used in Table 1-4.2
Thickness formula is
t p = P L M / 2 S E − 0.2 P
and L/r = above 16 means M factor calculate separately…..for another formula in App 1-4
-------------------------------------------
In my case the L/r is 16.6 and I have to calculate the M factor value separately.
-----------------------------------------------------------------
Here my questions are,
1. Is it wrong using thicknesses formula tp = 0.885 P L / S E − 0.1P.
in this condition (L/r is 16.6) as per ASME sec VIII div -1 UG -32 (e) .Why because I already consider the inside knuckle radius is 6% inside crown radius as per the code.
2. As per UG -32(e) and App 1-4, when I go for these L/r ratio?
Please help me in this query and am expecting your comments with references please …
[h=Torispherical Head Thickness Calculation problem, pls help me]2[/h]
Vessel ID: 2100 mm
Length (T/T): 3900 mm
Thickness: 6 mm (considered)
Vessel Type: Horizontal Cylindrical with Torispherical Dish End
I manually calculate this
Inside Crown Radius of the Torispherical is ( L ): 2112 (OD of the Vessel) &
Inside Knuckle Radius is ( r ) 126.72 (6% of Inside Crown Radius),
As per ASME Sec VIII Div – 1 UG 32 (e)
The condition ts/L ≥ 0.002 is satisfied
And the formula for the thickness calculation is tp = 0.885 P L / S E − 0.1P
-------------------------------------------
But as per ASME Sec VIII Div – 1 Appendix – (1- 4)
The same condition is ts/L ≥ 0.002
The L/r ratio is involves ……….
L /r ratio is inside crown radius to the inside knuckle radius, used in Table 1-4.2
Thickness formula is
t p = P L M / 2 S E − 0.2 P
and L/r = above 16 means M factor calculate separately…..for another formula in App 1-4
-------------------------------------------
In my case the L/r is 16.6 and I have to calculate the M factor value separately.
-----------------------------------------------------------------
Here my questions are,
1. Is it wrong using thicknesses formula tp = 0.885 P L / S E − 0.1P.
in this condition (L/r is 16.6) as per ASME sec VIII div -1 UG -32 (e) .Why because I already consider the inside knuckle radius is 6% inside crown radius as per the code.
2. As per UG -32(e) and App 1-4, when I go for these L/r ratio?
Please help me in this query and am expecting your comments with references please …
In short:
1. UG-32 formula applies to torispherical heads that are in a specific subset that the inside crown radius = the outside diameter of the skirt and the inside knuckle radius is 6% of the inside crown radius. Please note that the paragraph states ICR is EQUAL to OD and the IKR IS 6% of ICR. If your head is a true ASME F&D and meets these criteria, then use this formula.
2. Appendix 1-4 exists to deal with torispherical heads that have differing geometries, for example an 80/10 head, which has a crown that is 80% of the skirt OD and a knuckle that is 10% of the skirt OD. One would use an 80/10 head because it requires only about 2/3 the thickness that a true F&D head requires.
3. I always use App 1-4 first, then run UG-32e. Sometimes 1-4 is more liberal with the required thickness. Please examine factor M formula in App 1-4d and Table 1-4.2 of M values. Please contact me if you require additional help.
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