Chemical Engineering February 2022 - 33

Property/ performance
Common name
Chemical name
ASTM 1418 designation
Hardness range
(durometer)
Low temperature
(min. service), °F
High temperature
(max. service), °F
Abrasion
Cold
Heat
Acid (dilute)
Acid (concentrated)
Chemicals
Impermeability
Ozone
Sunlight
Solvents
Water
Weather
Generally resistant to
the following:
TABLE 1. MATERIALS AND PROPERTIES OF ELASTOMERS COMMONLY USED FOR EXPANSION JOINTS
Elastomer types
Chlorobutyl
Chloro-isobutylene-isoprene
CIIR
40-75
-60
to -10
250 to 300
Good
Good
Very good
Excellent
Good
Excellent
Very low
Excellent
Very good
Fair to good
Good
Good to excellent
Animal and
vegetable oils;
fats; greases; air;
water, oxidizing
chemicals; ozone
Generally attacked by
the following:
Oil; solvents;
aromatic hydrocarbons
EPDM/EPT
Ethylene-propylenediene
monomer
EPDM
40-90
-60 to -20
300
Good to excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Fairly low
Outstanding
Outstanding
Poor to failr
Excellent
Excellent
Vegetable and animal
fats, oils, ozone;
many strong and
oxidizing chemicals,
ketones, alcohols
Mineral oils, solvents,
aromatic
hydrocarbons
Hypalon
Chlorosulfonated
polyethylene
CSM
40-95
-60 to -30
275
Excellent
Good
Excellent
Excellent
Very good
Excellent
Low to very low
Outstanding
Outstanding
Poor
Fair
Excellent
Strong acids and
bases; freons;
hydroxides; ozone;
alcohols; and etching,
alkaline and hypochlorite
solutions
Ketones, esters;
certain chlorinated,
nitro and aromatic
hydrocarbons
These can include threaded, flanged,
weld, grooved and so on. Also, from
what material do the end fittings need to
be composed?
* D delivery. Is this item time sensitive?
If so, is rush delivery required?
Can a different type of expansion joint
be used temporarily or permanently? Air
freight may be required versus ocean or
truck freight.
The STAMPED criteria can go a long
way toward narrowing down the choices
in expansion joints, but there are still a
variety of choices within each of those
categories, and different designs are
available for particular conditions and
applications. Contacting an expansionjoint
vendor can be a valuable resource
for selecting the appropriate type of expansion
joint.
Neoprene
Poly-chloroprene
CR
40-95
-50 to -10
220
Excellent
Good
Very good
Excellent
Good
Fair to good
Low
Very good to
excellent
Very good
Poor
Good
Excellent
Moderate acids and
chemical, ozone,
oils, fats, many solvents,
oily abrasive
applications
Oxidizing acids;
esters and ketones,
aromatic, chlorinated
and nitro
hydrocarbons
Selection recommendations
STAMPED is a valuable tool for selecting
the appropriate type of expansion
joint. This acronym will get you well on
your way to selecting the proper expansion
joint for your application, however,
it is not the " end-all, be-all. " Some additional
design criteria, as well as common
knowledge to have in your back pocket,
include the following:
Rule of 250. The " Rule of 250 " concerns
pressure and temperature of the
media. If the pressure is lower than 250
psi and temperature lower than 250°F,
then rubber expansion joints should be
used. For applications above 250 psi
and temperatures over 250°F stainless
steel should be used. It is highly advised
to use stainless-steel expansion joints
for all steam and condensate applications.
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ENGINEERING WWW.CHEMENGONLINE.COM
FEBRUARY 2022
33
Buna-N
Butadiene
acrylonitrile
NBR
40-95
-40 to +30
240
Good
Good
Good
Good
Good
Fair to good
Low
Fair
Poor
Fair
Fair to good
Fair
Most hydrocarbons,
fats, oils, greases,
hydraulic fluids,
chemicals and
solvents
Ozone, ketones, esters,
aldehydes, nitro
and chlorinated,
hydrocarbons, polar
solvents, methyl
ethyl ketone
Natural rubber
Polyisoprene
NR/IR
30-90
-20 to 65
185
Excellent
Excellent
Good
Fair to good
Fair to good
Fair to good
Fairly low
Poor to fair
Poor
Poor
Fair to good
Fair
Water, air, averageconcentration
acids,
bases, alcohols,
salts, ketones, best
abrasion resistance
Ozone, strong acids,
bases, oils, solvents,
most hydrocarbons
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