Engineering Data/FAQs
Calculating Load Requirements
Two formulas that define the minimum load required to effect a seal on a
particular gasket are Wm1 and Wm2. When these formulas have been calculated, the
larger load of the two is the load necessary to effect a seal.
Let:

pi = 
3.14 
P = 
Maximum internal pressure 
M = 
Gasket factor "M" (M = 3 for spiral wound gaskets) 
Y = 
Seating stress "Y" (Y = 10,000 psi for spiral wound gaskets) 
N = 
Basic width of a gasket per chart (For raised face flanges see diagram 1a on the chart) 
B_{0} = 
Basic seating width of a gasket per chart (For raised face flanges, B_{0} = N/2) 
B_{1} = 
Effective seating width of a gasket; must be determined. 
ID = 
Inside diameter of gasket 
OD = 
Outside diameter of gasket For gaskets where the raised face is
smaller than the OD of the gasket face, the OD is equal to the outer
diameter of the raised face. 
Find:

ID = 
_______ 
OD = 
_______ 

Given the ID and OD, find the value of N. Then define B_{0} in terms of
N 
N = 
_______ 
B_{0} = 
_______ 

Determine if B_{0} is greater or less than 1/4", then find B_{1}: 

If B_{0} < or = 1/4", then B_{1} = B_{0} 

If B_{0} > 1/4", then B_{1} = (sq.root B_{0}) / 2 
B_{1} = 
_______ 

Using B_{1}, determine G: 
G = 
OD  [(B_{1})(2)] 

Now, insert these values in the final equations to determine minimum required load: 
When Wm1 and Wm2 have been calculated, the larger of the two numbers is the
minimum load required to seat a gasket. In most cases the available bolt load in
a connection is greater than the minimum load on the gasket. If not, higher bolt
stresses or changes in the gasket design are required for an effective seal.
NOTE:
Flange design code suggestions for low pressure applications calling for minimum
seating stress (Y value) are sometimes inadequate to seat the gasket because the
bolting and flange rigidity are insufficient to effect a proper seal. Care should
be taken to ensure that flange conditions provide a suitable seating surface. For
internal pressures to be contained, flange rotation and sufficient residual loads
must also be considered in the flange design.
WARNING:
Properties/application shown here are typical. Your specific application
should not be undertaken without independent study and evaluation for
suitability. For specific application recommendations consult Garlock.
Failure to select the proper sealing products could result in property
damage and/or serious personal injury.
Performance data published here has been developed from field testing,
customer field reports and/or inhouse testing.
While the utmost care has been used in compiling this information, we
assume no responsibility for errors. Specifications subject to change
without notice. This edition cancels all previous issues. Subject to
change without notice.
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