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C-25
Temperature
In most selection processes, the temperature of the
fluid at the gasketed joint should be considered first. This
will reduce the number of product candidates quickly, es-
pecially as temperatures go from 200°F (95°C) to 1,000°F
(540°C). When system operating temperatures approach a
particular gasket material's maximum continuous operating
temperature limit, an upgrade to a superior material is sug-
gested. In some situations cryogenic temperatures must
also be considered.
Application
The most important information under Application is
the type of flange and bolts used. The number, size and
grade of bolts used in the application determines the load
available. The surface area being compressed is calcu-
lated from the gasket contact dimensions. The load from
the bolts and the contact area of the gasket result in the
compressive load available to seal the gasket. We have
calculated and tabulated this information on standard ANSI
raised face flanges (see page C-45). Compressive stress
available on non-standard flanges must be calculated on
an individual basis. Without this information, we cannot
choose between various types of materials such as elasto-
meric (rubber) gaskets, compressed sheet, GRAPH-LOCK®
and GYLON® styles.
Media
There are thousands of different fluids. We cannot, in
this manual, make recommendations for all fluids. Fortu-
nately, however, there are a relatively limited number of
fluids that make up the vast majority of the media encoun-
tered in industry. A general overview of fluid compatibility is
provided for the most popular styles shown in this manual
(see Chemical Resistance chart, pages C-26 to C-38).
System cleanout and flushes should also be considered.
Additional information on products versus fluids is available
upon request.
Pressure
Next to be considered is the internal pressure of the
fluid at the gasketed joint. We list the maximum pres-
sure limits for each style. If severe and frequent pressure
changes are involved, we should be given the details, since
an alternative product may be needed.
Pressure (psi or bar) x Temperature (°F or °C)
We strongly recommend that pressure and tempera-
ture be considered simultaneously by using the following
procedure:
1. First select the Garlock style(s) being considered for
your application/service,
2. List the maximum pressure, temperature and P x T
value for the style(s),
3. Make sure the actual service conditions do not exceed
the style limitations in any of the three criteria. If they
don't, the style(s) can be used, provided all other
requirements are met. If they do exceed any one limit,
another style or styles should be considered. Rarely
can a style be recommended when the service condi-
tions of pressure and temperature are both at the
maximum limits for that style.
Example: BLUE-GARD® Compressed Asbestos-free
Gasketing Style 3000
1. Pressure Limit: 1,000 psig (70 bar)
2. Maximum Temperature Limit: 700°F (370°C);
Continuous Operating Temp.: 400°F (205°C)
3. P x T Limit: 350,000* (12,000)
At 1,000 psig (70 bar), maximum temperature is
350°F (180°C).
Important
Maximum pressure and P x T ratings are based on
the use of ANSI RF flanges at our preferred torque.
The ratings were developed using laboratory tests
at ideal gasketing conditions. Field conditions will
undoubtedly affect the gasket performance.
When approaching maximum pressure, continu-
ous operating temperature, minimum temperature or
50% of maximum PxT, consult Garlock Applications
Engineering.
We hasten to point out that this method for gasket
selection is merely a general guide and should not be the
sole means for selecting or rejecting a product.
* P x T based on 1/16" sheet thickness unless otherwise stated.
Gaskets
Garlock
®