Monty Mills – WSDOT Maintenance Operations Branch Manager
How Big is the Problem?
Corrosion Costs at WSDOT
 In F/Y ’09, we spent anywhere from $200 to $2000 on individual
dump trucks depending on region.
 95% of fleet corrosion costs are applied to dump trucks
 $3.5 m total repair costs - $417k on corrosion repair
 30% electronics & wiring
 22% chassis and brake
 12% engine, exhaust, fuel system components
 8% attachments & hydraulics
 6% body & sand/salt applicators
 6% cab components
 5% drive train & axle
 11% other
The Science of Corrosion
 Corrosion is the deterioration of material due
to a reaction with its environment.
 Galvanic corrosion is an electrochemical
process wherein an anode gives up electrons to a
cathode when they have physical and electrical
contact through an electrolyte (i.e. water).
Did not react well with its environment!
 Oxidation describes the loss of electrons to the
metal(anode).
 Reduction describes the formation of hydroxides,
usually ferrous hydroxide, or rust.
Susceptibility of Maintenance
Equipment to Corrosion
 Trucks and other equipment have a wide variety of metals:
 Steel – frame members, body panels, brake lines, etc.
 Cast Irons – engines, drive trains, brake drums, etc.
 Aluminum and Aluminum Alloys – fuel tanks, wheels, body
panels, etc.
 Magnesium Alloys – wheels, transmission housings, etc.
 Copper – wiring, radiators, brake lines, etc.
 Some of these metals are “anodic”, i.e., more prone to corrosion, while
others are “cathodic”, or less prone.
 Steel is often given a metallic zinc coating. The zinc sacrifices itself,
thereby prolonging the life of the component made from the zinc
coated steel.
Galvanic Corrosion Chart
How Do We Deal With Corrosion?
 There are two primary ways to deal with corrosion – Reaction
and Prevention
 Reactive methods focus on dealing with already established
corrosion by cleaning corroded parts with a rust removing
compound, or replacing the ones that are too far gone for rehab. A
reactive strategy may in some case be the most cost effective means
of dealing with corrosion if parts are easy to clean, or easily replaced
and fairly inexpensive.
 Preventive methods are a proactive strategy, and include coatings,
the use of corrosion resistant materials for equipment components,
dielectric grease, enclosed wiring connections, the use of sacrificial
anodes, and the use of corrosion inhibited products. Frequent and
regular washing of equipment can be considered a preventive
strategy.
Susceptibility of Maintenance
Equipment to Corrosion
During the winter, this equipment is
constantly exposed to moisture and the
presence of road salts and other chlorides.
Concentrations of chlorides, humidity,
temperature, pH, and presence of dissolved oxygen
are all factors which can determine the rate and
severity of corrosion.
Snow and ice materials tend to accumulate
in areas that are hard to see or clean. Left
unattended, these deposits will greatly speed
the corrosion process.
When Corrosion is Ignored or Untreated …..
Frames
Rot
Parts are
Destroyed
And this
Turns to
This
Types of Corrosion
 Intergranular Corrosion (IGC)
Forms at grain boundaries. Stainless steel can
be susceptible to this type of corrosion
after welding or high temperature exposure.
 Pitting Corrosion
Point specific corrosion at weak points resulting
in pits, the openings of which may be too small to
reveal the extent of the corrosion within.
 Galvanic Corrosion
When two dissimilar metals come into contact via an
electrolyte such as water, causing one (the anode) to
lose mass, and the other (the cathode) to form a
protective deposition – typically rust.
Types of Corrosion
 Crevice Corrosion
Somewhat similar to pitting corrosion. Typically
occurs in narrow gaps in metal to metal surfaces
such as dual frame chassis sections.
 Stress Corrosion Cracking
Limited to alloys such as aluminum and
magnesium where corrosion occurs at a joint or
bend where stress is present. The combination of
stress and corrosion can lead to failure of the part.
 Erosion Corrosion
Typically caused by the movement of corrosive
fluids over the metal surface. Pump components
are particularly susceptible.
Typical Corrosion On WSDOT Equipment
Deicers and Corrosion
Who are the bad actors?
Is any particular deicer more destructive than others?
What does research tell us?
 2003 WSDOT Salt Pilot Project - inconclusive as to which chemical deicer
(MgCl2, CaCl2, NaCl) was the most detrimental to metal coupons place on
highway hardware and maintenance vehicles.
 American Trucking Association Study - determined that sodium chloride had
the greatest effect to steel components, and aluminum was affected more by
magnesium chloride.
 2002 Colorado DOT study tested four different materials using mag chloride
and sodium chloride, and using a couple different test procedures. The ability
of mag chloride to re-hydrate showed the greatest cause for concern, and led
to the conclusion that magnesium chloride is more corrosive than sodium
chloride under humid environments, and sodium chloride is more corrosive
under immersion and arid environments.
Deicers and Corrosion
 What do our observations and other analytical information
tell us about deicer effects to metals?
 The most vocal critics of chemical deicers and the damage they can cause to
vehicles and equipment continues to be the trucking industry. The focus of
their ire has been primarily magnesium chloride. This issue continues to
get prominent feature in trade magazines.
 Agencies such as CDOT and MDT which use magnesium chloride as key
components of their snow and ice control operations have responded to
these complaints with counter claims of mag chlorides effectiveness and
studies indicating no significant difference between mag and sodium
chloride where corrosion is concerned.
Deicers and Corrosion
 What about snow and ice equipment?
Three major areas of attack:
 Steel & steel components
 Aluminum & aluminum components
 Wiring & electronics
Means of Corrosion Attack
 Aluminum Corrosion
 Aluminum has a natural protective oxide barrier.
 In high and low pH, the oxide barrier breaks down.
 Dissimilar metals will reduce barrier.
 Pitting develops.
 Pits promote continued corrosion due to lack of oxygen
 Steel Corrosion
 Steel corrodes in wet and humid environments.
 Steel corrodes uniformly across its surface.
 Corrosion Summary
 Salt solutions accelerate corrosion of steel and aluminum.
 Abrasives accelerate steel and aluminum corrosion.
 Stray electrical current accelerates corrosion. lack of oxygen.
 Dissimilar metals promote corrosion.
 Aluminum is the sacrificial metal when connected with steel.
WSDOT Fabrications for Corrosion Prevention
The valve body is enclosed
in a stainless steel box with
rubber stripping added to
all connecting surfaces.
The batteries are enclosed
in a sealed composite
material box. A plate is
placed over the batteries to
prevent material from
collecting on them. Rubber
covers are placed over the
terminals.
Valve Body Protection
The various components
enclosed in the valve body
box are expensive and critical
to the operation.
The use of a sealed
stainless steel enclosure
will help prolong the life
of these components.
Corrosion Prevention of Exposed Parts
Aluminum fuel tanks and stainless steel oil pans
replace mild steel units for added longevity. The
extra cost is insubstantial, especially within the
context of added life span.
Electrical control units are moved to the inside
of the cab and off of the floor. This prevents
corrosive materials which are tracked in by the
driver from corroding these units.
Other Ways to Prevent Corrosion
Keep the salt behind you!
Coatings
 Electrocoat (E-coat)
Electrophoretic deposition is a process in which
electrically charged particles are deposited out
of a water suspension to coat a conductive part.
The process is more commonly known as electrocoating
or E-coating. Automotive parts that are electrocoated
usually receive a zinc or iron phosphate treatment prior
to deposition. The coating is deposited onto
the substrate metal by applying an electrical
potential between the substrate metal (cathode)
and a suitable anode in the presence of
an electrolyte. The electrolyte usually consists
of a water solution containing salt of the metal
to be deposited and various other additions
that contribute to the plating process.
Coatings
 Mechanical plating
Finely divided metal powder is cold welded to the substrate by tumbling the
part, metal powder and a suitable media such as glass beads, in an aqueous
solution containing additional agents. Mechanical plating is commonly used
to apply zinc or cadmium to small parts such as fasteners.
 Electroless
In this non-electric plating system, a coating metal, such as cobalt or nickel, is
deposited on a substrate via a chemical reaction in the presence of a catalyst.
 Hot dipping
A form of galvanization. It is the process of coating iron, steel, or aluminum
with a thin zinc layer, by passing the metal through a molten bath of zinc at a
temperature of around 860 °F. When exposed to the atmosphere, the pure
zinc reacts with oxygen to form zinc oxide, which further reacts with carbon
dioxide to form zinc carbonate, which stops further corrosion in many
circumstances.
Best Practices to Prevent Corrosion
Corrosion protection on fleet equipment requires a
proactive maintenance approach
 Wash equipment and undercarriages to remove anti-icing chemical
residue. Repair damaged areas of any paint or surface coating as soon as
possible. Keep truck frames coated, sandblasted and painted as needed.
 Protect the electrical system the same as you would the chassis. Lubricate
sockets, pigtails, battery terminals and connections with a non-conductive
dielectric compound. To further protect against corrosion in areas like
electrical contacts, circuit switches and junction boxes; all electrical wiring
connections should be sealed against moisture with heat shrink tubing as
well as non-conductive, non-sodium based grease. When installing wire
ends use a non-puncturing style wire connector. We currently use
Weatherpak or Deutsch sealed connectors.
 Do not pierce wire jacketing - Never probe or puncture a hole in the wire
jacketing. This creates a path for contaminants to seep in, which causes the
wire to breakdown from the inside out. Include in equipment specs the use
of high quality weather proof terminals. Eliminate Junction boxes wherever
possible.
Best Practices to Prevent Corrosion
Wash vehicle daily, especially following anti-icing
activity to reduce magnesium and calcium chloride
build up
 Do not pressure wash vehicle, because water can be forced into areas and
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cannot escape, which leads to corrosion. High volume low pressure
washing is better.
Apply dielectric grease to plugs and sockets and re-apply dielectric grease
on plugs and socket pins as needed.
Every six months use a plug and socket brush with water (no soap) to clean
connectors. Minimize connectors to the extent possible by using
continuous wiring.
Be cautious of soaps containing degreasers.
Coat aluminum brake valves with rubberized undercoating.
Utilize stainless steel in place of mild steel or aluminum wherever practical.
Use plastic quick release brake valves in instead of aluminum.
Products We Use
 Martin Senour DTM 5225 3.5 VOC gray epoxy primer,
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NAPA
Martin Senour PRISM 3.5 VOC gloss black acrylic
urethane, NAPA
Martin Senour 6599 cleanable hardener, NAPA
NEUTRO-WASH™
Salt and Chloride Neutralizer from RHOMAR
industries
Battery Cleaner and Acid Detector from Noco®
Densyl ta6221pe, Denso North America Inc.
Current Corrosion Research
 Best Practices and Guidelines
for Protecting DOT Equipment
from the Corrosive Effects of
Chemical Deicers
 Sponsors: Alaska University Transportation Center & WSDOT
 Researcher: Western Transportation Institute (Xianming Shi P.I.)
 Objective: Identify, evaluate and synthesize best practices that can be
implemented to minimize the effects of deicer corrosion on DOT winter
vehicles and equipment, such as design improvements, maintenance
practices, and the use of coatings and corrosion inhibitors
 Deliverable: Recommendations on both procedures and materials to
address corrosion management needs with both existing trucks and
ordering new trucks
Best Practices and Guidelines for
Protecting DOT Equipment from the
Corrosive Effects of Chemical Deicers
 18 month project which includes a literature review, agency
surveys & interviews, laboratory investigation, and cost
benefit analysis
 105 responses to survey
 Four anti-corrosion coating products tested in mag chloride solutions
 Four spray-on corrosion inhibitors
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 Five salt removers
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 Mild steel 1018, stainless steel, and an aluminum alloy under continuous
immersion in a 3% mag chloride solution
 Another set of experiments to evaluate the benefits of frequent washing
and to evaluate the performance of select salt removers (vs soap and water)
Recently Completed Corrosion Research
 Investigating Longevity of Corrosion Inhibitors and
Performance of Deicer Products Under Storage and After
Pavement Application
 Sponsors: WSDOT, 10 state DOTs,
& 3 private entities.
 Researchers: WTI
 Objectives:
‐ Determine longevity of inhibitors in storage and after application
‐ Determine the effects of temperature, UV intensity, exposure, and
dilution on inhibitors
‐ Determine cost-effectiveness of inhibitors as a component of deicers
‐ Determine inhibitor benefit (if any) as freeze point suppressant
‐ Determine most effective deicer product for varying weather scenarios
A
B
C
D
E
…
400’
400’
400’
 Inhibitor Longevity Research (Western Transportation Institute for
WSDOT)
 Longevity – no significant degradation of inhibitors in storage or after
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control
Recently Completed
Corrosion Research
application. Inhibitors stayed mostly consistent by ratio with the chloride
component.
Effects of temperature, UV, etc .- generally insignificant for sodium chloride
and inhibitor and magnesium chloride and inhibitor, but significant for
calcium chloride and inhibitor.
Cost effectiveness - aside from corrosion
inhibition, no well demonstrated added
benefits.
Freeze point suppression – no significant
benefit from any inhibitor product.
Deicer effectiveness – of the three liquid products
studied, no major difference was found in performance.
400’
Previous Corrosion Research
 Winter Road Management Program Corrosion Testing
Report
 Sponsor: The American Trucking Association
 Researchers: Idaho Technology Center and National Institute for
Advanced Transportation Technology
 Objectives:
‐ Collect information on chemicals
‐ Document corrosion related problems
‐ Identify corrosion factors associated
with anti-icer chemicals
 Outcomes:
‐ Sodium chloride (NaCl) has the most dramatic effect on mass loss
in steel components, whether corrosion inhibited or not
‐ Aluminum is affected more by magnesium chloride (MgCl2)
‐ Washing diminishes corrosive effects of chloride salts, however it
can also force materials into cracks and crevices where it may stay
and produce corrosion
Previous Corrosion Research
 Winter Road Management Program Corrosion Testing
Report (continued)
 Outcomes (cont):
‐ Sealed connection wires performed
much better than butt connections,
and wire probes should be avoided
to prevent intrusion
‐ Corrosion inhibited products are more
effective at preventing corrosion than non-inhibited products
‐ Material coatings are a significant deterrent to corrosion, but must
be quality controlled and applied at thicknesses which are adequate
to prevent intrusion
‐ Corrosion prevention is generally more cost effective than
replacement of components
‐ Effective material application strategies can greatly reduce
exposure to corrosive chemicals
Previous Corrosion Research
 Investigation of Materials for the Reduction of Corrosion
On Highway Maintenance Equipment
 Sponsor: The Iowa Highway Research Board
 Researchers: Wilfred A. Nixon and Jing Xiong
 Objectives: Determine how corrosion occurs on maintenance trucks, find
methods to minimize corrosion, and suggest means of optimal
combination of approaches for a given maintenance situation.
 Outcomes:
 Corrosion inhibitors have differing performance for different chlorides.
Good results with one deicer may not carry over to others.
 Washing of equipment shows a clear benefit to corrosion reduction and
prolonged equipment life.
 Design changes on maintenance equipment have great potential for
reducing the likelihood of corrosion.
 Coatings are effective at preventing corrosion and more research needs
to be done to identify the most effective ones.
Additional Perspective on the Issue
 Sacrificial anode is an interesting idea but difficult to implement on vehicles since
it is hard to predict or control the distribution of the protective current flowing
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across the vehicle – Xianming Shi, PhD, PE
Apply dielectric grease to plugs and sockets; all electrical wiring connections
should be sealed against moisture with heat shrink tubing as well as nonconductive, non-sodium based grease; do not pierce wire jacketing
Utilize stainless steel in place of mild steel or aluminum wherever practical
Coat aluminum brake valves with rubberized undercoating
Keep truck frames coated, sandblasted and painted as needed
Wash vehicle daily(!) especially following anti-icing activity to reduce magnesium
and calcium chloride build up. Do not pressure wash vehicle, because water can be
forced into areas and cannot escape, which leads to corrosion
Utilize rear mounted material application equipment as much as possible
Work with maintenance crews and management to identify and utilize effective
application methods which prevent over applications of salt or anti-icers
Don’t leave materials on board for extended periods, or park equipment in salt
laden environments
Resources & Other Research
 Pacific Northwest Snowfighters (PNS)
http://www.wsdot.wa.gov/partners/pns/
 Information on deicing product specifications and corrosion testing
 Qualified Products List (products meeting PNS Corrosion Spec)
 Corrosion related research
 National Association of Corrosion Engineers (NACE International)
http://www.nace.org/content
- Protecting People, Assets and the
Environment from the Effects of Corrosion
 THE CORROSION SOCIETY
 The World Corrosion Organization http://www.corrosion.org/
 Raising Awareness About Corrosion and Corrosion Protection Around the
World
Resources & Other Research
 CORROSION EFFECTS OF MAGNESIUM CHLORIDE AND SODIUM
CHLORIDE ON AUTOMOBILE COMPONENTS - Prof. Yunping Xi, and
Zhaohui Xie, University of Colorado at Boulder
http://cospl.coalliance.org/fez/eserv/co:5153/tra210024internet.pdf
 CORROSION COSTS AND PREVENTIVE STRATEGIES IN THE
UNITED STATES - Publication No. FHWA-RD-01-156 FHWA Contact: Y.
Paul Virmani, HRDI
http://www.corrosioncost.com/pdf/techbreif.pdf
 Evaluation of Corrosion Failure in Tractor-Trailer Brake System - Wilson,
D F, Kenik, E A, Blau, P J
http://trid.trb.org/view.aspx?id=798242
Questions