Durable Steel Systems for Fuel Tanks

Preferred Preferred Customer: Customer: Durable Steel Systems for Fuel Tanks Durable Steel Systems for Fuel Tanks A Status Report on Corrosion Studi...
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Durable Steel Systems for Fuel Tanks

Durable Steel Systems for Fuel Tanks A Status Report on Corrosion Studies conducted by the Strategic Alliance for Steel Fuel Tanks (SASFT) including The American Iron and Steel Institute (AISI) Presented by Peter Mould Program Manager, SASFT/AISI Doug Paul The Magni Group

Presented at Great Designs in Steel Seminar February 19, 2003

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Durable Steel Systems for Fuel Tanks

Preferred Preferred Customer: Customer:

Today’s Presentation z z z

z Background on SASFT and genesis of SASFT’s corrosion testing program

Peter Mould

z Corrosion program and preliminary findings

Doug Paul

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Durable Steel Systems for Fuel Tanks

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SASFT is z z z z Organized by American Iron and Steel Institute (AISI) to improve steel’s position in the fuel tank market z A global alliance of various stakeholders in the steel fuel tank business: — steel companies — manufacturers of steel tanks and fuel system components — suppliers to manufacturers y welding equipment y organic/inorganic coatings z Made up of 29 companies from 8 countries/3 continents

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Durable Steel Systems for Fuel Tanks Genesis of SASFT’s Corrosion Study z Regulatory drivers z Stringent evaporative emissions (e.g., PZEV) z 15-year life of the fuel system Can “steel” meet a 15-year life requirement? z Corrosion Evaluation Team (CET) was formed to address the durability issue

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Durable Steel Systems for Fuel Tanks Corrosion Evaluation Team (CET)

CET Accomplishments

Steel Producers Arcelor Bethlehem Corus Dofasco Kawasaki National Nippon U.S. Steel

Tank/Component Manufacturers Martinrea Int.

Suppliers Magni

zSelected several steel “systems” of production intent products to meet 15-year minimum life zEstablished External and Internal tests zDeveloped unique test specimens zReviewed tests/procedure with OEM’s beforehand z Monitored testing at ACT Laboratories (Hillsdale, Michigan) zzz

Doug Paul, Chairman of CET, to review

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Durable Steel Systems for Fuel Tanks Steel Systems Tested

zzz

3 groups representing different steel tank philosophies worldwide

Pre-painted steels

— — — —

paint (9 – 11 microns thick) applied to steel coils tank halves are formed and assembled touch-up paint applied at welds used by North American OEMs

Post-painted steels

— — — —

tank halves are formed from unpainted steel assembled post-paint applied (PVC, acrylic or bituminous wax) used by Japanese OEMs

Bare steels

— — — —

tank halves formed from unpainted steel assembled no paint applied used by European OEMs

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Durable Steel Systems for Fuel Tanks Specific Steels Tested Pre-painted Low carbon steel - EG Zn-Ni Low carbon steel – EG Zn-Ni Low carbon steel - HD Aluminized 304L stainless

— — — — — — —

Magni pre-paint #331 with Cr6 10μ thick Magni pre-paint #336 without Cr6 10μ thick Magni pre-paint #369 with Cr6 9μ thick Inorganic paint

Post-painted Low carbon steel - Terne Low carbon steel – Tin-Zinc Low carbon steel – HD Aluminized 436L stainless

— Acrylic anti-chip 350μ thick without Cr6 — Cover paint 20μ thick without Cr6 — Acrylic anti-chip 150μ thick with Cr6 — Zn rich primer 50μ thick

Bare Steel 304L stainless

— no pre- or post-paint

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Durable Steel Systems for Fuel Tanks Corrosion Tests

z z z selected after consultation and review

with several automakers

External Tests z Neutral Salt Spray (ASTM B117) — chosen mainly to compare with large body of published data — exposure for 2,000 hours z Cyclic Test (SAE J2334) — generally regarded as most representative of road conditions and Automotive Proving Ground experience — exposure for 160 cycles z All Specimens – Domes, Scribes, Weld Flange, Gravel Area

Fuel Test z Aggressive Ethanol (CE10A) — contains sodium chloride, sulfuric and acetic acid — exposure for 39 weeks at 45°C

Triplicate test specimens

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Durable Steel Systems for Fuel Tanks Life Equivalency SASFT Test

Salt Spray

2000 hours

(ASTM B117)

Cyclic

160 cycles

(SAE J2334)

Fuel

39 weeks

Exposure

Other Tests

1000 hrs. to 2000 hrs.

Life Equivalency

⎯ ⎯

80 cycles

20 years 10 years

26 weeks

15 years 10 years

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Durable Steel Systems for Fuel Tanks Test Specimens

zzz

designed to represent conditions of a steel tank in automotive corrosive environments

External Test Specimen

6"

Olsen dome Weld Plastic Clip

6"

scribe line (applied at test laboratory)

gravel impact zone

2 inches max.

CETrfqOct29_01.doc

REF: CETrfq1Oct29_01.doc; SASsctpt11_20_01

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Durable Steel Systems for Fuel Tanks Status of Tests

z z z External tests completed z z z Fuel tests - ongoing

Criteria for failure

z z z Perforation

Corrosion assessment z z z Qualitative description of extent of red rust

(none, some, moderate, etc.), photos z z z Quantitative

— creep back at scribe lines — frequency and size of chip zones from gravel — pit depths (depths above 0.1mm)

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Durable Steel Systems for Fuel Tanks General Results External Tests No perforation observed in: —any specimen —any steel sample —at any location Some variations in white and red rust occurred —among steel specimens within a given material —at different locations All steel systems zzz

should meet a minimum of 15 years exposure

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Durable Steel Systems for Fuel Tanks Results Results

(continued) (continued)

Fuel Tests z Tests ongoing … Indications to date — no perforation — minor red rust — no pits z Results expected late 2003

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) A Pre-painted steel systems

EG Zn-Ni + Magni #336/no Cr6

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) A Pre-painted steel systems

HD Aluminized + Magni #369/Cr6

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) A Pre-painted steel systems

304L + Inorganic paint

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) B Post-painted steel systems

Terne + acrylic anti-chip paint (350μ) + top coat (20μ) — no Cr6

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) B Post-painted steel systems

Tin-Zinc + acrylic anti-chip paint (350μ) + top coat (20μ) — no Cr6

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) B Post-painted steel systems

HD Aluminized + acrylic anti-chip paint (150μ)

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) B Post-painted steel systems

436L Stainless steel + organic primer

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Durable Steel Systems for Fuel Tanks Results

zzz

Photos – Cyclic test (after 120 cycles/15 years) C Bare steel

304L Stainless Steel

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Durable Steel Systems for Fuel Tanks Summary and Conclusions z Based on laboratory simulated External corrosion tests, several steel systems are expected to exceed the 15-year life required by ARB of California z Tests to assess the resistance of the same steel systems to aggressive fuel (CE10A) are ongoing. Preliminary findings indicate 15-year life will be exceeded. z Other steel systems are also undergoing external testing — pre-painted HDGA — post-painted Aluminized (thicker paints) z All the steel systems tested are commercially available

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Durable Steel Systems for Fuel Tanks See examples of the 3 steel systems

zzz

Pre-painted steels

Electrogalvanized Zn-Ni + Magni pre-paint

Post-painted steels

Hot dip coated Terne Hot dip coated Tin Zinc

Bare steels

Hot dip coated Aluminized Stainless zzz

in tanks at the SASFT exhibit

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