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For high temperature steam, 7182 brand formulated AFLAS is the
best-in-class
sealing elastomer.
Three
decades of field service and 10,000 hour test data validate the
stability of formulated Aflas in hot aqueous environments.
Examining the retention of tensile strength (integrity) and the
retention of elongation (extensibility) reveals a sealing material
capable of long-term service in high temperature steam and hot aqueous
fluids. (To learn about this approach to evaluating elastomers read our
technical paper "Thermal Stability of BPAF and TAIC Cured Fluoroelastomers")
A standard EPDM is the wrong choice for Steam.
Steam and hot water
service seals, gaskets, and o-rings have traditionally been made
of EPDM. However, at temperatures exceeding
100C, EPDM seals quickly fail (see graph at right).
Auda and Hazleton of Exxon Chemicals Co., Elastomers Technology
Division (an historic supplier of EPDM elastomer) published a
study entitled "Ethylene Propylene Elastomer Technology for
Improved High Temperature Serviceability" regarding the
life expectancy of EPDM in hot applications. In dry heat
temperatures exceeding 100C (212F), their study demonstrated a
sudden and dramatic loss of integrity (retained tensile) and
extensibility (retained elongation). The failure mechanism is
oxidation. However, a Y-267 type EP is an exception to this rule.
In HTHP steam where oxygen is absent, a Y-267 EP such as our
compound 7204 performs exceptionally well.
FKM is the wrong choice for steam. In the 1970’s, Seals Eastern
evaluated the aging of a high fluorine content, low VF2 containing
grade of FKM
class fluoroelastomer in steam. Temperatures and time
frames exceeding the capability of EPDM were studied. Multiple
AS568-214 o-rings of the fluorelastomer were
aged in a time sequence up to 12,000-hours in 175C (347F) continuous
steam.
The saturated steam / hot water was a controlled pH of 7.0-7.5.
Usually, a slightly basic pH is maintained to prevent
corrosion in all such steam systems. The effects of steam on
an FKM elastomer are depicted below. The failure mechanism is
dehydrohalogenation despite the low level of VF2 in the
elastomer.
850 Hours |
1,700 Hours |
2,700 Hours |
3,700 Hours |
4,700 Hours |
5,800 Hours |
6,700 Hours |
9,200 Hours |
11,100 Hours |
7182 brand formulated AFLAS is the best
elastomer available for steam service. There is
no tendency of this FEPM class rubber to oxidize like a standard EPDM or
dehydrohalogenate like a VF2 containing fluoroelastomer (FKM). We offer
three compounds that have proven to be best-in-class over the past three
decades.
FEPM |
Compound |
Duro |
Description |
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7182D |
80 |
Formulated AFLAS ® for Steam, Hydrocarbons, Acids,
and Bases and other chemical families. |
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7182X |
80 |
Formulated AFLAS ® for Steam, Hydrocarbons, Acids,
and Bases and other chemical families. Ultra-low compression set. |
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7182B |
90 |
Formulated AFLAS ® for Steam, Hydrocarbons, Acids,
and Bases and other chemical families. Resists extrusion. |
EP |
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7204 |
90 |
Y-267 type EP for geothermal steam and HTHP steam service. |
Technical Papers:
Premium Quality Seals...
For a Cleaner, Safer, More Reliable World.TM
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FastDash ™ is a trademark of Seals Eastern, Inc.;
OringOnline ® is a registered trademark of Seals Eastern, Inc.;
7182 ™ is a trademark of Seals Eastern, Inc.;
AFLAS ® is a registered trademark of Asahi Glass Co., Ltd.;
Viton ® is a registered trademark of Dupont Performance Elastomers, LLC.;
Fluorel ® is a registered trademark of 3M.
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