|
The sealing
is a result of the compressive forces created by sufficient bold
load, and also works to fill the imperfections on the mating surfaces
to be sealed. Key factors involved in choosing a suitable material
for a given gasketing application include:
Temperature - possibly the most important
factor in choosing a gasket material. When higher temperatures at
the gasketed joint need to be sealed, the potential choices are
quickly eliminated. If the system operating temperatures approach
a gasket materials max. continuous operating temperature threshold,
the next best material should be chosen.
Chemical compatibility to the media
to be sealed against (including flushes and system cleanouts). There
are many different fluids and gasses to seal against, and many different
choices of gasket materials to seal against them.
Pressure at the gasketed joint. The
internal pressure of the fluid should be a determining factor in
choosing a sealing material. If severe cycling or pressures changes
occur frequently, a more robust material may be required.
Application - this includes all factors
such as the number, grade and size of bolts to create compression,
the surface areas of the sealed joint.
Because pressure and temperature are so closely connected, it is
often effective to consider them together by measuring Pressure
x Temperature or PXT value. Review the specifications of the material
you are considering - if they are both near the max. continuous
operating limits of the application, a more robust material should
be used.
An important factor to consider in selecting materials is that most
testing for OEM products is conducted under laboratory conditions.
Actual field environments must be considered before a recommendation
for materials can be made.
- Common sealing materials include for die-cut,
compressed sheet gasketing: compressed non-asbestos, vegetable fiber,
neoprene, nitrile (buna-N), red rubber.
> Bolt
Torque Values for ASME B16.5 raised face flanges, with A193
grade B7 bolts, compressed sheet recommendations from Garlock Sealing
Technologies. Class 150# and 300#. (External
link to Garlock.com)
- Resiliency and strength
make spiral wound gaskets a good choice for a variety of applications
and environmental conditions. They are made from winding a thin
strip of metal wire, with soft fillers added to create an effective
seal, and often have an outside centering ring, with an inner ring
to offer additional radial strength.
Spiral wound gaskets have markings that indicate the
manufacturer, the winding and filler materials, the pipe size (nominal),
and the materials that the inner and outer rings are made from.
The markings conform to ASME B16.20.
- One of the most chemically-resistant
materials available, PTFE can fit the bill for extreme sealing with
sheet gasketing, gasket tape, joint sealant, and universal gasket
configurations. In addition to resisting most chemicals, the expanded
PTFE gaskets are outstanding at resisting creep and cold flow. There
are also gaskets created specifically for low bolt load, or for
use in sealing fragile pipe flanges.
for high temperatures,
and heat dissipation.
> More Info
on Grafoil®
and a variety
of packings and different sealing sets.
> More Info
Call us at 800-727-3257 to determine your the
correct compressed sheet gasketing material for your next sealing
project.
|
Gaskets
Compressed
Sheet Materials
Spiral Wound (semi-metallic) gaskets
