650-XXX
Title: /
Flush Type Clean Out Cover & Flange Thicknesss, Table 5-10
Date: / April 17, 2013Contact: / Name : Jamie Marchitello
Company
Phone : 215-356-6835
E-mail :
Purpose: / To provide mathematical equations for calculating thickness of FTCO Cover plate and Bolting Flange valid for all listed sizes of FTCO and for all design liquid heights.
Source: / B Mistry E-Mail
Revision: / 0
Impact: / The business impact of this item is neutral.
Rationale: / API-650 provides only Tabulated Values in Table 5-10 for thickness of FTCO Cover Plates and Bolting Flanges and only for listed design liquid heights. Basis of Tabulated values have not been disclosed. Tabulated values are not much of use for computrized design or tanks with design liquid height exceeding shown in the table 5-10. Also, thickness of cover plate and bolting flange is not directly proporsional to design liquid height. Thicknesses are proportional to square root of design pressure(design liquid height). Using interpolation between any design liquid hieght will result in thickness which is not technically correct.
This agenda item provides an equation to calculated FTCO Cover and Bolting Flanges that is valid for any design liquid height (desin pressure).
Derived Equation is shown in detail and have been verified against the Tabulated values.
Calculated values are all within +/- of values shown in Table 5-10 which have been rounded up.
Proposal: / Revise 5.7.7.7, correct Table 5-10 and add foot fote “g”. Add thickness limitations in 5.7.7.6 for Bottom Reiforcing Plates per Table 5-10.(changes shown in red)
5.7.7.7The dimensions of the cover plate, bolting flange, bolting, and bottom-reinforcing plate shall conform to Tables 5-9a, 5-9b, 5-10a and 5-10b. When corrosion allowance is specified, it is to be added to the cover plate, bolting flange thicknesses, and bottom- reinforcing plate.In lieu of values shown,thicknesses may be determined in accordance with equations in 5.7.7.6and 5.7.7.7
Where:
= Nominal Thickness of Cover Plate and Bolting Flange (mm);(inch)
h= Vertical Height of clear opening in (mm); (inch)
h+a= Span Distance for flat plate design in. (mm); (inch)
a= SI 150 mm; USC a= 6 inches.
H= Maximum Design Liquid Level (5.6.3.2) (meter); (Ft.)
G= Specific Gravity of Stored Product, not less than 1.0
Υ= Water Density Factor; SI 9.81/1000Mpa /m, USC 62.4/144 psi/ft.
Sd= Design Stress = =0.6 Sy
Sy= Built in Yield Strength, SI 205 Mpa; USC 30000 psi
Note: Built in low Yield strength is deliberate and intentional to provide leak tight bolted joint, limiting deflection.
C= Shape Coefficient for rectangular plates
C=0.55 for size 200x400 ;(8x16)
C=0.3 for size 600X600 ;(24x24)& 1200x1200;(36x36)
C=0.4 for size 900X1200 ;(36x48)
CA= Corrosion Allowance (mm); (inch)
Ex. Of 21.9m tall tank with 200mm tall cleanout.
(200 + 150) x + 0 = 0.XXX
Ex. Of 72’ tall tank with 8” tall cleanout.
(8 + 6) x + 0 = 0.4323
Add Foot Note g, In Table 5-10a and 5-10b
In lieu of values shown,thicknesses may be determined in accordance with equations in 5.7.7.6and 5.7.7.7.
Correct Thickness of Cover Plates and Bolting Flange in Table 5-10 for some size and heights, as they do not agree with calculated values. Only very minor corrections are needed in few places.
Add Thickness limitations for bottom reinforcing plates in 5.7.7.6 as below as shown in Table 5-10.
5.7.7.6
SI Units
tb=minimum thickness of bottom reinforcing plates (mm) ; <=25 mm +CA for 200x400, <=28 mm+CA ,for 600x600 <= 40mm +CA, for 900x1200 & ,<= 45 mm +CA for 1200x1200
US Customary Units
tb= minimum thickness of bottom reinforcing plates (mm) ; <=1” +CA for8x16, <=1 1/8” + CA for 24X24 <= 1 ½”+CA for 24x36 & ,<= 1 ¾” +CA for 48x48
Note: Thickness of bolting flange is the same as cover plate.
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