compatibility summary of fueling infrastructure materials with
TRANSCRIPT
Compatibility Summary of Fueling Infrastructure Materials
with Aggressive Ethanol Blended Test Fuels
Presented by Mike Kass
Oak Ridge National Laboratory
ORNL Co-Authors:
Tim Theiss, Chris Janke, and Steve Pawel
Supported by:
US Department of Energy Offices of the
Biomass Program (OBP) & Vehicle
Technology Program (VTP)
Presented to:
23rd National Tanks Conference
St. Louis, MO
March 20, 2012
This presentation does not contain any proprietary,
confidential, or otherwise restricted information.
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Presentation Outline
Rationale &Test Protocol
Plastic Results
Elastomer Results
Metal Results
Future Activities
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Rationale: How is compatibility affected by ethanol concentration (E0 to
E10 to E15 and higher ethanol blends…)?
Analysis of solubility parameters
suggests that gasoline blended with
lower ethanol concentrations are less
compatible with polymeric materials
10
15
20
25
30
0 20 40 60 80 100
Solu
bili
ty p
aram
ete
r, M
Pa
1/2
Ethanol concentration, vol.%
Range of most dispenser elastomersE10
E15
E85
0.00E+00
5.00E-06
1.00E-05
1.50E-05
2.00E-05
2.50E-05
3.00E-05
3.50E-05
0 10 20 30 40 50 60
Co
nd
uc
tivit
y, 1
/Ω-m
Ethanol concentration, vol%
The electrical conductivity (and therefore
corrosion potential) of ethanol-blended
gasoline increases with ethanol
concentration for metallic materials
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Compatibility was primarily assessed by evaluating volume change and
degree of softening or hardening following exposure to the test fuel
Volume swell (of saturated polymers) is important since it is a physical means
of assessing solubility of the polymer with fuel chemistry
» Solubility relates to the potential of the test fluid to permeate and dissolve
one or more polymer components
» Expansion produces stress in rigid polymers
» Volume swell is used to rank compatibility among o-rings and seals
Softening (loss of hardness) typically corresponds with volume swell and is a
measure of the deformation potential
In the wetted or saturated state
Volume loss (shrinkage) indicates:
» The extraction of one of more polymer components by the fluid
» Less material available to seal interfaces
Softening indicates fluid retention or degradation, while increased hardness
(embrittlement) indicates plasticizer removal
In the dried state
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Materials were chosen as representative of those used in fueling storage and
dispensing equipment
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The complete list of plastic materials includes those used in
flexible piping and in rigid piping/UST systems
Thermoplastics Thermosets
High Performance Polymers 1. Fluoropolymers: (PTFE & PVDF) 2. Polyphenylene sulfide (PPS)
Poly and Vinyl Ester Resins 1. Isophthalic polyester resin (1:1
ratio) pre-1990 resin 2. Isophthalic polyester resin (2:1
ratio) post-1990 resin 3. Terephthalic polyester resin
(2:1 ratio) post-1990 resin 4. Novolac vinyl ester resin
(advanced)
Mid-Range Polymers 1. Polyesters: (PET, PETG, PBT) 2. Acetals: (POM & Acetron GP copolymer) 3. Nylons: (nylon 6, nylon 6/6, nylon 12, & nylon 11) (note: nylon 11 is made from vegetable oil)
Commodity Polymers 1. Polyethylene: (HDPE & F-HDPE) 2. Polypropylene (PP)
Epoxies 1. Room temperature cured 2. Heat cured
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Test specimens were exposed to the test fluid in a large stainless
steel tank with stainless steel hardware
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Test fuels were formulated according to SAE J1681 and ASTM D471
specifically developed for materials compatibility studies
Ref Fuel C (50% toluene, 50% isooctane) is a
controlled and repeatable gasoline surrogate
CE25a, CE50a & CE85a (correspond to 25, 50, and
85 % aggressive ethanol-Fuel C blend)
Ethanol contains 0.9% aggressive water-acid solution
Aggressive solution component
Grams per liter of ethanol
Deionized water 8.103
Sodium chloride 0.004
Sulfuric acid 0.021
Glacial acetic acid 0.061
Aggressive elements represent worst-case
contaminant levels found in actual use
The elevated test temperature (60oC) rapidly ages the
specimens to assess relative compatibility in a
reasonable timeframe
Bare coupons
mass
volume
hardness
Exposed to
test fuels for
60oC/16 weeks
Removed and
maintained in
wetted condition
mass
volume
hardness
Dried at 60oC
for 65 hours
mass
volume
hardness
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-30
-25
-20
-15
-10
-5
0
5
10
-5 0 5 10 15 20 25 30
Po
int C
han
ge in
Har
dn
ess
(we
t) fr
om
Bas
eli
ne
Volume Change (wet), %
Fuel C
CE25a
CE50a
CE85a
PPSPET
In general, the volume swell was accompanied by a corresponding
drop in hardness (increase in softening). Residual fuel in the polymer
is likely responsible for this effect
softer
harder
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In general, the high performance and mid-range polymers (excluding nylons)
exhibited highest swelling with 25% aggressive ethanol
-5
0
5
10
15
20
25
0 20 40 60 80 100
Vo
lum
e C
han
ge (w
et)
, %
Ethanol Concentration, %vol.
PPS
PTFE
PVDF
PET
PETG
PBT
POM
Acetron GP
-30
-25
-20
-15
-10
-5
0
5
10
0 20 40 60 80 100
Po
int C
han
ge in
Har
dn
ess
fro
m (w
et)
Bas
elin
e
Ethanol Concentration, %vol.
PPS
PTFE
PVDF
PET
PETG
PBT
POM
Acetron GP
Slight change in hardness was
observed, except for PETG
softer
harder
Negligible swell: PPS, PET, PTFE
High swell: PETG
Modest swell: PVDF, POM, PBT
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The nylons and thermoset resins also exhibited peak swell at 25% ethanol.
However for PP and HDPE peak swell occurred at Fuel C (CE0).
The swelling behavior for PP, and
HDPEs achieved max. swell for Fuel C
and decreased with increasing ethanol
concentration
Petroleum-based nylons exhibited
moderate swell with exposure to
ethanol. Bio-based nylon 11 exhibited
higher swell.
Polyester thermoset resins exhibited
high swelling with exposure to ethanol -5
0
5
10
15
20
25
30
35
40
0 20 40 60 80 100
Vo
lum
e C
han
ge (w
et)
, %
Ethanol Concentration, %vol.
Nylon 12 Nylon 6
Nylon 6,6 Nylon 11
Vinyl ester resin Terephthalic polyester resin
HDPE F-HDPE
PP
The level of softening corresponded
with the observed swell
-20
-15
-10
-5
0
5
10
0 20 40 60 80 100
Po
int C
han
ge in
Har
dn
ess
(we
t)
Ethanol Concentration, %vol.
softer
harder
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After drying at 60oC/65 hours, some level of fuel was retained within
the plastics
-10
-5
0
5
10
15
20
25
30V
olu
me C
han
ge F
rom
Baseli
ne C
on
dit
ion
, %
Wetted
Dried
Nylon 12 lost mass
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In general the hardness (following dry-out) decreased with
increasing dry-out volume (or mass)
The increase in mass and volume following dry-out indicates that residual
fuel is present in the plastic structure. The one exception is nylon 12
which lost mass with exposure to Fuel C and ethanol.
-10
-8
-6
-4
-2
0
2
4
6
8
-10 -5 0 5 10 15 20
Po
int C
han
ge in
Har
dn
ess
fro
m B
ase
lin
e (d
ry)
Volume Change Following Dry-out, %
Fuel C
CE25a
CE50a
CE85a
Nylon 12
PPS
PET
softer
harder
In general the change
in hardness was
minimal and
corresponded with the
degree of swell
Materials which
experienced the
highest level of
softening were PETG
and the thermoset
polyester resins
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Observations for Plastic Materials
Negligible property change observed for PPS, PET, PTFE
Peak swell occurred at CE25a for PVDF, POM, PBT, PETG, nylons and
thermoset resins.
Moderate property change observed for PVDF, PBT, Acetals, HDPEs, nylon 6
and nylon 6,6 was raised slightly.
Highest property changes observed for nylon 11, nylon 12, PETG, PP, and
vinyl and polyester resins
Volume and softening of PVDF, acetals, nylons, PBT, PETG, and thermoset
resins were increased to varying degrees with exposure to ethanol
PP and HDPE properties improved with ethanol concentration
In this study, nylon 12 was the only plastic material observed to lose mass &
volume with exposure to ethanol
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The elastomer study looked at seven material types which were
representative of those used in o-rings, seals/gaskets, and hoses
Chemical Name
ASTM D1418
Abbreviation
M-Group (saturated carbon molecules in the main
macro-molecule group)
Fluorocarbon Rubber FKM
R-Group (unsaturated hydrogen carbon chain)
Neoprene Rubber
Nitrile Butadiene Rubber
Styrene Butadiene Rubber
CR
NBR
SBR
Q-Group (silicone in the main chain)
Silicone Rubber
Fluorosilicone Rubber
PVMQ
FVMQ
U-Group (carbon, oxygen and nitrogen in the main
chain)
Polyurethane
AU
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For elastomers peak swell occurred at 17% aggressive ethanol. Higher ethanol
concentrations (50 and 85%) lowered the wet volume (accompanied by a
corresponding decrease in hardness)
0
20
40
60
80
100
120
140
160
0.00 20.00 40.00 60.00 80.00 100.00
We
t Vo
lum
e C
han
ge, %
Ethanol Concentration, % vol.
Polyurethane
Neoprene rubber
Styrene butadiene rubber
Silicone Rubber
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
0.00 20.00 40.00 60.00 80.00 100.00
We
t Vo
lum
e C
han
ge, %
Ethanol Concentration, % vol.
FC#1 (66%F)
FC#1 (68%F)
FC#1 (70%F)
FC#1 (67%F)
FC#2 (66%F)
FC#2 (70%F)
FC#2 (69.5%F)
FC#2 (67%F)
Fluorosilicone
0
5
10
15
20
25
30
35
40
45
0.00 20.00 40.00 60.00 80.00 100.00
We
t Vo
lum
e C
han
ge, %
Ethanol Concentration, % vol.
NBR #1
NBR #2
NBR #3
NBR #4
NBR #5
NBR #6
Fluoroelastomers NBRs
Polyurethane
Neoprene
SBR
Silicone
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However, plasticizer extraction was observed in some elastomer types
even though the volume swell at 85% ethanol was low
-60
-50
-40
-30
-20
-10
0
10
20
30
0
10
20
30
40
50
60
0.00 20.00 40.00 60.00 80.00 100.00
Po
int C
han
ge in
Har
dn
ess
Fo
llo
win
g D
ryo
ut
We
t Vo
lum
e C
han
ge, %
Ethanol Concentration, % vol.
NBR #1NBR #2NBR #3NBR #4NBR #5NBR #6
For example: The NBRs showed low to negligible volume change with exposure to
85% ethanol. However, plasticizers were still removed resulting in embrittlement
and shrinkage.
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Elastomer summary:
For the majority of the elastomers peak swell occurred at CE25a
Many of the elastomers were highly sensitive to ethanol concentration and
exhibited very low volume change with exposure to CE85a. In most cases
the volume change was lower for CE85a than for Fuel C.
However, hardness results indicate that extraction and/or structural changes
had taken place with exposure to CE85a, even though the volume was
unchanged from the baseline condition.
Bottom Line: Volume swell alone may not be sufficient to determine
compatibility!
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Cr-plated
brass
Ni-plated
aluminum
exposed
brass
exposed
aluminum
* new for this series
The metal coupon study included galvanically-coupled specimens
to better reflect field conditions
Single Material Coupons
» 304 stainless steel
» 1020 carbon steel
» 1100 aluminum
» Cartridge brass
» Phosphor bronze
» Nickel 201
Plated Coupons (exposed fully plated
and with plating partially removed to
generate galvanic couple
» Terne-plated (Pb) steel
» Galvanized (Zn) steel
» Cr-plated brass
» Cr-plated steel
» Ni-plated aluminum
» Ni-plated steel
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Metal Results Summary
The corrosion rates based on uniform weight loss were minor for all
materials
Exposure of the substrate steel accelerated corrosion due to a combination
of galvanic coupling of dissimilar metals and the increased conductivity of
the environment (CE50a, CE85a) compared to previously examined test
fluids (reference fuel C, CE10a-CE25a
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Future Plans
Issue report detailing plastic results and elastomers and metals (CE50a
and CE85a)
Evaluate compatibility to other biofuels
Mike Kass Oak Ridge National Laboratory PH: (865) 946-1241 Email: [email protected]