EDITORIALM A N A G I N G E D I T O RGRETCHEN A. JACOBSONT E C H N I C A L E D I T O R

JOHN H. FITZGERALD III, FNACES TA F F W R I T E R

MATTHEW V. VEAZEY

GRAPHICSE L E C T R O N I C S P U B L I S H I N G S P E C I A L I S T

TERI J. GILLEYM A N A G E R

E. MICHELE SANDUSKY

ADMINISTRATIONN A C E E X E C U T I V E D I R E C T O RD I R E C T O R — P U B L I C AT I O N S

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EDITORIAL ADVISORY BOARDEugene Bossie

Corrosion Engineering Services, Inc.

John P. BroomfieldCorrosion Consultant

Raul A. CastilloThe Dow Chemical Co.

Irvin CottonArthur Freedman Associates, Inc.

Bruce D. Craig, FNACEMetCorr

C.P. Dillon, FNACEC.P. Dillon & Associates

Arthur J. FreedmanArthur Freedman Associates, Inc.

Orin HollanderHolland Technologies

W. Brian HoltsbaumCC Technologies Canada, Ltd.

Otakar JonasJonas, Inc.

Ernest KlechkaCorrMet Engineering Services

Joram LichtensteinCorrosion Control Specialist, Inc.

George D. MillsGeorge Mills & Associates International, Inc.

James “Ian” MunroCorrosion Service Co., Ltd.

John S. Smart IIIJohn Smart Consulting Engineers

L.D. “Lou” VincentCorrpro Companies, Inc.

2 CORTEC SUPPLEMENT TO MATERIALS PERFORMANCE February 2003

Corrosion Preventionand Control with VolatileCorrosion Inhibitors

TABLE OF CONTENTS

3 Migrating Corrosion Inhibitor Protection of Steel Rebar in ConcreteBezad Bavarian and Lisa Reiner

6 Corrosion Protection of Military Equipment WorldwideAnna M. Vignetti, Luka Miskovic, and Tadija Madzar

10 Vapor Phase Corrosion Inhibitors Protect Fire Water SystemsAshish Gandhi

14 Environmentally Friendly VCIsChristophe Chandler and Boris A. Miksic, FNACE

19 MCI®s, VCIs and VpCIs: Literature Research Index

Now embarking on its 60th year, NACE International is built upon de-cades of knowledge and expertise from dedicated members who havedeveloped and continue to drive the latest and best methods for con-

trolling corrosion in every industry and environment. Among the many prod-ucts that have been refined over the years to effectively fight corrosion arevolatile corrosion inhibitors (VCIs), the related vapor-phase corrosion in-hibitors (VpCIs), and migrating corrosion inhibitors (MCIs). Originally de-veloped to protect boilers and piping of ships to be mothballed, VCIs noware being used to prevent corrosion in pipelines, military vehicles and equip-ment, cooling towers, concrete structures, storage tanks, electronics, pack-aging systems, and more.

Cortec Corp.—also celebrating a milestone anniversary in 2003—has beenin the business of developing and applying VCIs, VpCIs, and MCIs for 25years. Company researchers have authored numerous conference papers,technical briefs, and journal articles on the science and applications of thesetechnologies, several of which are included here.

One article reveals how VCIs are being used effectively in environmen-tally sensitive areas because they are nontoxic and nonpolluting. Anotherprovides details on laboratory and field applications of VpCI products thatare being used by military organizations worldwide. An article on MCIs re-veals how these inhibitors actually penetrate concrete to protect the sup-porting steel rebar within, while another describes how VpCIs provide pro-tection from corrosion in wet and dry fire water pipe systems. An extensiveliterature research index is provided for those interested in learning moreabout these corrosion inhibitors and their applications.

Innovative corrosion control systems will continue to evolve as research-ers find new and better ways to protect materials from the damaging—andsometimes devastating—effects of corrosion. By keeping pace with thesetechnologies and relying on the expertise of corrosion professionals, orga-nizations will improve operations, reduce costs, and help fulfill the crucialmission of NACE and its members to protect people, assets, and the envi-ronment from the effects of corrosion.

According to the finalreport of a 2-year na-tionwide study releasedto the U.S. Congress inMarch of 2002,1 theU.S. incurs billions ofdollars in corrosion

costs each year for reinforced concretestructures (e.g., highway bridges, wa-terways, ports, and drinking water andsewer systems). The annual direct costof corrosion for highway bridges aloneis estimated to be $8.3 billion (Figure1). Indirect costs related to traffic de-lays and lost productivity are estimatedto exceed 10 times the direct cost ofcorrosion maintenance, repair, and re-habilitation.

Previous studies have verified thebenefits of using migrating corrosioninhibitors (MCIs), the importance ofgood concrete, and the significance ofingredients used to make the concretefor protection of reinforced concretestructures from corrosion.2-10 Steel re-inforcing bars (rebar) embedded inconcrete show high resistance to cor-rosion because the alkaline environ-ment provided by the cement paste inthe concrete promotes the formationof a protective ferrous oxide (FeO)film. The rebar’s ability to remain pas-sivated and protected from corrosivespecies, such as carbonation and chlo-ride ions that can penetrate throughthe concrete pores to the rebar oxidelayer, is influenced by the water-to-cement ratio, permeability, and electri-cal conductivity of concrete. In highlycorrosive environments, the passivelayer will break down, leaving therebar vulnerable to carbonation andchloride attack. In these environments,corrosion prevention is necessary.

Advancing MCI TechnologyMCI technology was developed to

protect the embedded steel rebar andthe concrete structure. Recent MCIsare based on amino-carboxylate chem-istry, with the most effective types ofinhibitor interacting at the anode andcathode simultaneously.2-4 MCIs pen-etrate into the existing concrete to pro-tect steel from chloride attack.6 Theinhibitor migrates through the con-crete capillary structure, first by liquiddiffusion via the moisture normallypresent in concrete, then by its highvapor pressure, and finally by follow-

MigratingCorrosion InhibitorProtection of SteelRebar in ConcreteBEZAD BAVARIAN AND LISA REINER

Laboratory analysis determined the effectivenessof migrating corrosion inhibitors (MCIs) for reinforced

concrete. Nyquist plots showed high polarization values forconcrete treated with inhibitor. X-ray photoelectronspectroscopy (XPS) analysis confirmed that MCI migratedthrough the concrete. XPS depth profiling indicated that theinhibitor was able to suppress corrosion even in thepresence of chloride. The effects of applying MCI directly tothe rebar into the concrete were not apparent. Additionaldata are required to make any conclusion about theeffectiveness of an application method.

FIGURE 1

$3.8 billionReplace structurallydeficient bridges overthe next 10 years

$0.5 billionMaintenance painting

of steel bridges

$2.0 billionMaintenance and cost of

capital for concretebridge decks

$2.0 billionMaintenance and cost of capital for

concrete substructures (notincluding decks)

ing hairlines andmicrocracks. Thediffusion processrequires time forthe MCI to reachthe rebar and forma protective layer.

MCIs can be in-corporated intoconcrete batchesas an admixture orcan be used bysurface impregna-tion of existingconcrete struc-tures. With sur-face impregna-tion, MCIs diffuseinto the deeperconcrete layers toinhibit the onsetof steel rebar corrosion. Bjegovic andMiksic demonstrated the effectivenessof MCIs over 5 years of continuous test-ing.2-4 They also showed that the MCIadmixture is effective in repairing con-

crete structures.2 Laboratory tests havealso proven that MCIs migrate throughthe concrete pores to provide rebarwith protection from corrosion evenin the presence of chlorides.4,5

Distribution of the estimated $8.3 billion annual direct cost of corrosionfor highway bridges.1

The maximum aggregate size was~1/2 to 5/8 in. (12 to 15 mm). Grada-tion was uniform. Coarse aggregate wascrushed stone, natural gravel (rivergravel), quartzite, quartz, and sandstone.Fine aggregate primarily comprisedsand, quartz, and some clay. The water/cement ratio was moderately low at~0.50. Paste content was moderate andunhydrated cement grains rarely werefound in pastes. The degree of consoli-dation was good, the contacts of matrixwith aggregates were relatively close,and some minor openings were visibleon the polished or broken surfaces. Thedegree of air entrainment was measuredto ~1.2 to 1.5% (28 to 30 mm2/mm3 or700 in.2/in.3). Compressive strengthswere ~3,100 to 3,950 psi (21 to 27 MPa).

Prior to being placed in the concretesample, the steel rebar (class 60) wasexposed to 100% relative humidity toinitiate corrosion. The rebar was cov-ered with a 1-in. (2.5-cm) layer of con-crete. On all samples, a copper/coppersulfate (Cu/CuSO4) reference electrodewas used, with an Inconel 800† metalstrip serving as the counter electrode.The concrete samples were partiallyimmersed (87.5% of the height) in a 3.5%sodium chloride (NaCl) solution. Thetop portion of the concrete sample wasexposed to air.

Changes in the resistance polariza-tion (Rp) and the corrosion potential ofthe rebar were monitored weekly usingdirect current (DC) electrochemical andalternating current (AC) electrochemi-cal impedance spectroscopy over a 450-day period to determine the effective-ness of the MCI products. After 450 daysof immersion in NaCl solution, severalconcrete samples were cut open and therebar removed for x-ray photoelectronspectroscopy (XPS) analysis to verify in-hibitor migration through the concreteand its adherence to the rebar structure.

Investigation ResultsThe assessment of the corrosion in-

hibitors for the three concrete densitieswas based on open circuit potential (cor-rosion potential) values, Rp values, andXPS analysis.

OPEN-CIRCUIT POTENTIALSAccording to ASTM C876,11 if the

open-circuit potential is –200 mV or lessnegative, a 90% probability exists that

-600

-500

-400

-300

-200

-100

0

0 50 100 150 200 250 300 350 400 450

Time of Submersion (Days)

Pote

ntia

l (m

V)

L 2022

L 2021

L untreated

H 2022

H untreated

H 2021

M untreated

M Rebar 2022

M Surface 2022

M Mortar 2022

FIGURE 2

Corrosion potential vs time, ASTM C876-91, MCI 2022and 2021 compared with unprotected concrete (variousconcrete densities).

FIGURE 3

0

5,000

10,000

15,000

20,000

25,000

Time (Days)

Rp (Ω

)

0 50 100 150 200 250 300 350 400 450

L 2022L 2021L untreatedH 2022H 2021H untreated

Comparison of Rp for MCI-treated concrete (variousdensities) with untreated samples.

ing the rebar surface. To de-termine the effects of con-crete density and applicationmethod when using MCIs, 10specimens comprising threeconcrete densities were com-pared for corrosion inhibitionproperties. Six concretesamples were prepared withcorrosion inhibitors using dif-ferent application methods(Table 1). Two concretesamples were left untreatedas references.

Concrete samples werecast (dimensions 20 x 10 x 10cm) using commercial-gradesilica, Portland cement, flyash, and limestone (concretemixture ratio: 1 cement/2fine aggregate/4 coarse aggre-gate). Low-density concreteat 2.09 g/cm3 (130 lb/ft3) wasprepared with a 0.5 water/cement ratio with a concretemixture for 2.5 ft3 (20.4 kg ce-ment, 40.8 kg fine aggregate,81.7 kg coarse aggregate, and10 kg water). Medium-densityconcrete at 2.24 g/cm3 (140 lb/ft3) was batched using a 0.50water/cement ratio, with a

TABLE 1

TEST SAMPLESConcrete Sample(0.5 water/cement ratio) Concrete Density MCI Application MethodA (2 samples) Low (L) (2.08 g/cm3) 2022 MCI-treated concrete surface

B (2 samples) Low (L) (2.08 g/cm3) 2021 MCI-treated concrete surface

C (1 samples) Low (L) (2.08 g/cm3) Untreated No MCI application

D (2 samples) High (H) (2.40 g/cm3) 2022 MCI-treated concrete surface

E (2 samples) High (H) (2.40 g/cm3) 2021 MCI-treated concrete surface

F (1 samples) High (H) (2.40 g/cm3) Untreated No MCI application

G (2 samples) 2.24 g/cm3 Untreated No MCI application

H (2 samples) 2.24 g/cm3 2022 MCI-treated concrete surface

I (2 samples) 2.24 g/cm3 2022 MCI-coated rebar cast inconcrete

J (2 samples) 2.24 g/cm3 2022 MCI-mortar mixture appliedto concrete surface

Concrete Density andMCI Application Method

The rate of MCI migration in part de-pends on the density and permeabilityof the concrete. A high-density concretethat impedes the movement of corrosivespecies to the surface of the rebar mayalso prevent the inhibitor from reach-

concrete mixture for 2.5 ft3 (21.8 kg ce-ment, 43.6 kg fine aggregate, 78 kgcoarse aggregate, and 10.9 kg water).High-density concrete at 2.40 g/cm3 (150lb/ft3) was batched using a 0.50 water/cement ratio with a concrete mixturefor 2.5 ft3 (24 kg cement, 47 kg fine ag-gregate, 94.4 kg coarse aggregate, and11.8 kg water).

†Trade name.

no reinforcing steel has corroded. Cor-rosion potentials more negative than –350 mV are assumed to have >90% like-lihood of corrosion. Corrosionpotentials for the high-density samples(H2021, H2022, H untreated) were be-t w e e n–400 mV and –600 mV after 128 days ofimmersion in NaCl (Figure 2). The un-treated control sample (L untreated)had a corrosion potential of –295 mV atthe end of testing. MCI-treated, low-den-sity samples (L2022, L2021) had corro-sion potentials ranging from –120 mVto –145 mV. The inhibited samples witha density of 2.24 g/cm3 showed corro-sion potentials between –48 mV to –175mV during the first 130 days of testing,regardless of the application method.The low-density samples had signifi-cantly less negative corrosion potentials,indicating good passivation.

POLARIZATION RESISTANCEFigure 3 shows the Rp values at the end

of testing to be from 13,000 to 22,000 Ωfor the low-density samples treated withMCI. The high-density concrete showedsignificantly less corrosion inhibition,with Rp values ranging from 1,000 to2,000 Ω. Rp values for non-treatedsamples ended at 3,170 Ω for low-den-sity samples and 1,200 Ω for high-den-sity concrete. Changes in Rp value werenot immediately observed, indicating thatdiffusion of corrosive species or MCIs intothe concrete requires an induction period(~120 days). Figure 4 illustrates the sub-stantial difference between low-densityand high-density concrete samples.

XPS ANALYSISFigure 5 shows the XPS spectra for

two rebar removed from the MCI-treatedsamples after 450 days. The inhibitorshad penetrated the concrete layer,reaching the rebar and slowing downcorrosion. Figure 6 illustrates the depthprofiling of steel rebar removed fromMCI-treated concrete samples, indicat-ing that a 140-nm layer of amine-richcompound (amine-based MCI) was de-tected on the rebar’s surface. Chloridewas also found on the rebar surface,with deposits varying from 0.99 and 0.84wt% concentration for MCI 2022 andMCI 2021, respectively. The XPS resultsshowed that MCI and corrosive species(chloride ions) had migrated throughthe concrete, but the MCI had neutral-ized the corrosive species and protected

0.0001 0.001 0.01 0.1 1 10 100 1,000 10,00010

100

1,000

10,000

100,000

Frequency (Hz)

l Z l

(Ω)

L untreated-Day 1 L untreated-Day 380H2021-Day 1 H2021-Day 324H2022-Day 1 H2022-Day 327L 2021-Day 1 L 2021-Day 381L 2022-Day 1 L 2022-Day 383

FIGURE 4the steel rebar.

ConclusionsLower-density concrete

samples provided an easierpath for the inward diffusionof MCI, resulting in faster cor-rosion retardation. The MCIproducts were found to offerprotection for the steel rebarby suppressing the chlorideions. They are capable of in-hibiting corrosion in aggres-sive environments, such asseawater. MCIs continue todemonstrate their effective-ness in protecting reinforcedconcrete structures.

References1. G.H. Koch, M.P.H. Brongers,

N.G. Thompson, Y.P. Virmani, J.H.Payer, “Corrosion Costs and PreventiveStrategies in the United States,” ReportFHWA-RD-01-156, www.corrosioncost.com/home.html.

2. D. Bjegovic, B. Miksic, “MigratingCorrosion Inhibitor Protection of Con-crete,” MP 38, 11 (1999): pp. 52-56.

3. D. Bjegovic, V. Ukrainczyk,“Computability of Repair Mortar withMigrating Corrosion Inhibiting Admix-tures,” CORROSION/97, paper no. 183(Houston, TX: NACE, 1997).

4. D. Rosignoli, L. Gelner, D.Bjegovic, “Anticorrosion Systems in theMaintenance, Repair & Restoration ofStructures in Reinforced Concrete,” In-ternational Conf. Corrosion in Natural& Industrial Environments: Problemsand Solutions (Italy, May 23-25, 1995).

5. D. Darling, R. Ram, “GreenChemistry Applied to Corrosion andScale Inhibitors,” MP 37, 12 (1998): pp.42-45.

6. D. Stark, “Influence of Designand Materials on Corrosion Resistanceof Steel in Concrete,” R and D BulletinRD098.01T (Skokie, IL: Portland Ce-ment Association, 1989).

7. B. Bavarian, Lisa Reiner, “Corro-sion Protection of Steel Rebar in Con-crete Using MCI Inhibitors,”EUROCORR 2001 (Italy, October 2001).

8. B. Bavarian, D. Bjegovic, M.Nagayama, “Surface Applied MigratingInhibitors for Protection of ConcreteStructures,” CONSEC ’01 (Vancouver,BC: June 2001).

9. B. Bavarian, Lisa Reiner, “Corro-sion Protection of Steel Rebar in Con-crete Using MCI Inhibitors,” Researchin Progress Symposia (chaired by F.Mansfeld), CORROSION/2001 (Hous-ton, TX: NACE, 2001).

10. B. Bavarian, Lisa Reiner, “Corro-sion Inhibition of Steel Rebar in Con-crete Using MCI Inhibitors,”

Comparison of AC impedance spectroscopy bode plotresults for low (L)- and high (H)-density concrete.

1000 800 600 400 200Binding Energy (eV)

56

48

40

32

24

16

8

Inte

nsity

(CPS

)

MCI 2022

x104

MCI 2021 0 1s

N 1s

C 1s

C1 2P

FIGURE 5

XPS spectrum of steel rebar removed from MCI-treatedconcrete after 450 days of submersion. Large area (1,000 by800 mm) survey scan. Lens mode electrostatic; resolutionpass energy –160; anode: Mg (150 W).

FIGURE 6

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 500 1000 1500 2000 2500Etch Time (Seconds)

Conc

entra

tion,

atm

%

2022 N (1s)2022 Cl (2p)2021 N (1s)2021 Cl (2p)

XPS depth profiles of steel rebar removed from MCI-treatedconcrete samples after 450 days of submersion (etchedusing 2kV argon ions).

LISA REINER is a Graduate Research Associate atthe Material Science and Corrosion Laboratories ofCalifornia State University, Northridge. She hasbeen investigating migrating corrosion inhibitors toimprove the durability of concrete-reinforcedstructures for the past 4 years, and she has morethan 20 papers and presentations. She has a B.A.in economics from the University of California atSanta Barbara, an M.S. in engineering, and is amember of SAMPE and IEEE.

EUROCORR 2000 (London U.K., September 2000).11. ASTM C876, “Standard Test Method for Half-Cell

Potentials of Uncoated Reinforcing Steel in Concrete”(West Conshohocken, PA: ASTM, 1991).

BEHZAD BAVARIAN is a Professor of MaterialsEngineering at California State University, Northridge.He has authored more than 156 papers on corrosion,corrosion protection, and environmentally assistedcracking. He has a Ph.D. from Ohio State Universityand has been a member of NACE, TMS, ASM, andSAMPE for more than 22 years.

Corrosion significantlyaffects the perfor-mance of militaryequipment, shortensthe time frame for use,and increases the riskof catastrophic failure.

The result is billions of dollars in lostassets each year and jeopardized warreadiness. Military organizations world-wide continue to take steps to objec-tively evaluate different corrosion pre-vention methods in vehicles, aircraft,high-tech electronics, facilities, navalvessels, and weaponry.

Among the different corrosion pre-vention methods tested, vapor phasecorrosion inhibitor (VpCI) technologycontinues to provide an effective, en-vironmentally friendly, and relativelyinexpensive method of controlling cor-rosion. VpCIs are chemical compoundsthat have significant vapor pressuresthat allow molecules to vaporize andthen adsorb on metallic surfaces.1-2

When added in small concentrations,VpCIs effectively check, decrease, orprevent atmospheric corrosion caused

by the reaction of the metal with theenvironment.

Corrosion PreventionMethods

Table 1 presents four methods cur-rently employed by military organiza-tions to prevent corrosion. They includeproducts that block moisture and otheratmospheric contaminants; productsused to absorb moisture; alternatives,such as dehumidification; and VpCIs.

Laboratory and FieldExperiments

LABORATORY TESTINGSpecific laboratory testing for ASTM

International and Military (MIL) Speci-fication standard test procedures wasconducted to support the successfuluse of VpCIs in field applications.

FINGERPRINT REMOVALPROPERTIES TEST

Handling metal components canlead to corrosion as a result of the cor-rosive nature of the salts in human skin.Because it is difficult to ensure thathands are covered when handlingmetal equipment, a military test andspecification was developed to test theability to remove fingerprint oils andprovide corrosion protection. Table 2presents the procedure, and the resultsare shown in Table 3.

VpCI OIL BASE COATING TESTA VpCI oil base coating was tested

on carbon steel panels (SAE 1010) un-der highly humid conditions (ASTMD17483), salt spray conditions (ASTMB1174), and cyclic environmental con-ditions (ASTM G855). The test methodssimulated the environment underwhich military equipment may be usedor stored. Table 4 shows the results.

VpCI TEMPORARYSOFT COATING TEST

A VpCI temporary outdoor coatingwith self-healing properties was testedfor various properties according to themilitary standard method, MIL-C-16173E6 Grade 1, Class 1. Table 5 pre-sents the results.

FIELD APPLICATIONSMany VpCI products and systems

used to protect military equipment from

CorrosionProtection of

Military EquipmentWorldwide

ANNA M. VIGNETTI, LUKA MISKOVIC, AND TADIJA MADZAR

Corrosion damages billions of dollars of militaryassets every year. Military organizations evaluate

and utilize a variety of preservation methods that protectequipment from corrosion without compromising warreadiness. This article describes types of preventionemployed by military organizations and details severallaboratory and field applications of vapor phase corrosioninhibitor products and systems used successfully bymilitary organizations worldwide.

TABLE 1

CORROSION PREVENTION METHODS USED BY MILITARY ORGANIZATIONSCorrosionPrevention

Method Product Type Benefits DisadvantagesWater-displacing products Petroleum-based Relatively inexpensive Costs increase with additives

(light oils or thixotropic Water displacement (e.g., contact inhibitors, extreme-greases) Create a barrier coating on pressure additives) needed to

metal surfaces enhance protection Excellent permanent protection High labor and material costs for

application and removal ofproduct

Use of solvent-based cleanersfor product removal makesthese products unsafe for theworker and environment

Water-absorption products Silica gel (dessicants) Economical alternatives for Difficult to calculate specifictemporary protection moisture that will be present

Effective for storage and (i.e., requires more dessicant andshipping inspection)

Effective in electronic and Costs increase with the additionelectrical operations of more dessicant and inspections

Airtight seal is required butdifficult and expensive to achieve

Dehumidification Dehumidifier Can be successful if air flow to Dehumidifier Vapor barrier bags the metal is totally restricted Electricity mandatory for

Vapor barrier bags are dehumidifier and not availableexcellent for one-time use (offer in remote locationsa sturdy multilayer film) Difficult to keep a seal on the

Good way to protect electronics metal object High cost of equipment and

associated upkeep Vapor barrier bags

High costs of materials andlabor needed to create air-tight protection

Not a good method to useduring operations

VpCIs Anodic inhibitors (e.g., Anodic inhibitors Anodic inhibitorssodium nitrite [NaNO2], Prevent metal corrosion Negative effect on workerdicyclohexylamine nitrite, Cathodic inhibitors safetysodium benzoate) Slow cathodic reaction Negative effect on

Cathodic inhibitors Precipate onto cathodic sites, environment Mixed inhibitors restricting diffusion of corrosive

species Mixed inhibitors

Adsorbed onto metal surface,creating a monomolecular layer

Monomolecular film acts as a buffer,maintaining pH at optimum range forcorrosion resistance

Provide a universal effect oncorrosion process

TABLE 2

PROCEDURE PER MIL-C-15074,7 CORROSION PREVENTION, FINGERPRINT REMOVALStep Procedure

1 Prepare fingerprint test solution (7 g sodium chloride [NaCl], 1 g urea [CO(HN2)2], 4 g lactic acid [C3H6O3], 1 L deionized water).

2 Place a pad of gauze on a flat dish and place 1.5 mL of fingerprint solution on pad.

3 Sand a rubber cork with sandpaper and rinse with deionized water.

4 Wash five steel panels with methanol (CH3OH) and air dry.

5 Place fingerprint solution on panels using rubber cork and immediately place in an oven set at 121°C for 5 min.

6 Place one panel in boiling methanol for 2 min. Immerse a second panel in 1,1,1-trichloroethane (CH3CCl3) for 1 min.Immerse three panels in a VpCI product for 2 min.

7 Place all panels in a dessicator with water for 24 h.

8 After 24 h, open the dessicator and visually evaluate the condition of the panels.

ing. The products were tested and ap-proved for use.8 Placing the product inenclosed electronic cabinets or boxesallows the inhibitor to form a molecularbarrier on the multimetal surfaces of theelectrical components. Because the po-tential adverse effects of molecular lay-ers were of great concern to NASA andthe U.S. Navy, extensive testing was con-ducted that showed VpCI products tobe safe for even the most sensitive equip-ment (i.e., optical coatings and instru-ments).9 VpCI products effectively andeconomically protect telecommunica-tion and radar equipment located inhighly corrosive environments.

VpCI PROTECTIONFOR THE U.S. NAVY

The U.S. Navy uses VpCI-emittingdevices for electronics on naval aircraft,ships, and air stations.2,10 These productsalso are used effectively on other siteson naval vessels to combat corrosioncaused by continuous exposure to a salt-laden environment. In addition, VpCIadditives are used in coatings and oils.

VpCI PROTECTION OF WEAPONRYVpCI products and systems are avail-

able in the following forms: film andpaper for storage and shipping, lubri-cating oils, protective coatings, andemitting devices. Each form is aproven, reliable, and effective methodfor protecting weaponry. Recent test-ing has been completed on the use ofVpCIs in the conservation of infantryweapons in the Armed Forces of theRepublic of Croatia.

Degreased and cleaned, unpaintedweaponry parts were coated with athin layer of protective MIL-P-46002B11

VpCI oil, using a brush or brush soakedin oil (Figure 1). The weaponry wasthen mounted onto special holders andleft for 10 to 15 min. so excessive pro-tective oil could drain into previouslyprepared containers (Figure 2). The oil-coated weaponry was placed into pro-tective MIL-B-22020C12 VpCI bags. Thebags were sealed with self-adhesivetape or were welded shut using spe-cialized equipment (Figure 3). The pro-tected weaponry was loaded intocrates for warehousing, making surenot to damage the VpCI bags. Theweapons were stored in different cli-mates—a mild, Mediterranean climate;a cold, mountain climate; and a dry,continental climate.

TABLE 3

MIL-C-15074, CORROSION PREVENTION, FINGERPRINTREMOVAL TEST RESULTS

Material Results Fingerprint RemovalMethanol No corrosion 100%

1,1,1-trichloroethane Severely corroded 0%

VCI-327 No corrosion 100%

TABLE 4

VpCI OIL BASE COATING TEST RESULTSEnvironmental ASTM Standard Coating Film TestTest Condition Test Method Thickness DurationHumidity D1748 2 mils (50 µm) 2,000 h

Salt Spray B117 2 mils (50 µm) 170 h

Prohesion G85 2 mils (50 µm) 500 h

TABLE 5

MIL-C-16173E, GRADE 1, CLASS 1 RESULTS FOR VpCITEMPORARY SOFT COATING

Test Test Method (Section) ResultMaterial 3.2 Pass

Toxicity 4.8 Pass

Film characteristics 4.6.11.7 Pass

Solvent distillation endpoint 4.6.1 Pass

Discernibility 3.6 Pass

Stability 4.6.6 Pass

Recovery from low temperature 4.6.6.1 Pass

Uniformity 4.6.6.1.2 & 4.6.11.4 Pass

Storage stability 3.73 Pass

Flash point 4.6.2 Pass

Removability 4.6.10.1 Pass

Salt spray 4.6.11.4 Pass

Weather-accelerated 4.6.11.5 Pass

Flow resistance 4.6.15 Pass

Sprayability 4.6.7 Pass

Corrosion 4.6.8.1 & 4.6.8.2 Pass

Low-temperature adhesion 4.6.12 Pass

Drying 4.6.13 Pass

corrosion around the world havebeen tested, approved, and docu-mented. The following field applicationsvary from simple corrosion protectionto more sophisticated solutions.

VpCI PROTECTION FOR NASAThe U.S. National Aeronautics and

Space Administration (NASA) success-fully used a simple application of a VpCIcoating to protect the O-rings in the

space shuttles from corrosion caused bysaltwater atmospheric contamination.The coating was approved under MIL-C-16173E (Table 5) to meet NASA’s re-quirement to eliminate or reduce thecorrosion.

VpCI products also have proven use-ful in protecting electronics. NASA per-formed extensive testing to addressVpCI interference with Hyperbolic Ig-nition and Lox Mechanical Impact Test-

After 3 years of storage, the pro-tected weaponry was examined forevidence of corrosion. All metal partsand barrels were in excellent condi-tion—including the weaponry storednear the sea in the presence of a sig-nificant concentration of chloride saltsand weaponry enclosed in plastic bagsthat were damaged around the mouthof the barrel and sights. The examina-tion verified the protective effect ofVpCIs and extended the conservationperiod, resulting in significant savingsfor weaponry protection.

Benefits of VpCI TechnologyThrough widespread use of VpCI

products and systems, military organi-zations continue to benefit from suc-cessful corrosion prevention and thefollowing additional advantages associ-ated with using VpCI technology:

Ease of application

Efficiency in application andnonremoval (removal only ifnecessary)

Environmentally friendly

Economic advantages

• Low-cost products

• Reduced labor costs forapplication and removal

• Reduced maintenance costs

• Less-frequent reapplication ofproducts

• Reduced loss of assets

Enhanced combat readiness

Extended life expectancy ofequipment.

ConclusionsVpCI technology continues to ad-

vance as evidenced by expanded utili-zation and testing of VpCI productsand systems by military organizationsfor preventing corrosion. VpCI use iseffective in protecting the safety ofmilitary personnel, eliminating hazard-ous waste disposal, reducing laborcosts, and preserving war readiness.The efficiency and ease of applicationalong with the benefit of nonremoval(in most instances) make VpCI technol-ogy a desirable alternative for militaryorganizations.

References1. O.L. Riggs, Jr., C.C. Nathan,

ed., “Corrosion Inhibitors,” CORRO-

SION/73 (Houston, TX: NACE, 1973).

2. K.L. Vasanth, “Vapor Phase

Corrosion Inhibitors for Navy Appli-

cations,” CORROSION/97, paper no.

179 (Houston, TX: NACE, 1997).

3. ASTM D1748, “Standard Test

Method for Rust Protection by Metal

Preservatives in the Humidity Cabi-

net” (West Conshohocken, PA:

ASTM, 1983).

4. ASTM B117, “Standard Practice

for Operating Salt Spray (Fog) Appa-

ratus” (West Conshohocken, PA:

ASTM, 1997).

5. ASTM G85, “Standard Practice

for Modified Salt Spray (Fog) Testing”

(West Conshohocken, PA: ASTM,

1998).

6. MIL-C-16173E (Arlington, VA:

U.S. Department of Defense).

7. MIL-C-15074, “Corrosion Pre-

vention, Fingerprint Removal” (Ar-

lington, VA: U.S. Department of De-

fense).

8. NASA Internal Report no. 96-

2T0178, September 1996.

9. Creo Electronics Corporation,

Burnaby, British Colombia, Indepen-

dent Test Report for VCI Sensitivity

on Optical Coatings and Instruments,

November, 1989.

10. K.L. Vasanth, “Corrosion In-

hibition in Naval Vessels,” CORRO-

SION/96, paper no. 233 (Houston,

TX: NACE, 1996).

11. MIL-P-46002B (Arlington, VA:

U.S. Department of Defense).

FIGURE 2

VCI oil draining into previously prepared containers.

FIGURE 1

Degreased and cleaned, unpainted weaponry parts coatedwith VpCI oil.

FIGURE 3

Weaponry to be packed in VpCI bags

12. MIL-B-22020C (Arlington, VA: U.S. Depart-

ment of Defense).

ANNA M. VIGNETTI is Vice President of Salesand Marketing at Cortec., 4110 White BearPkwy., St. Paul, MN 55110. She has beeninvolved in the chemical industry as anadministrator, salesperson, and manager since1984. She is active in associations in thechemical, coatings, corrosion, and inksindustries, making significant contributions totechnical and sales development. She has aB.A. degree in marketing and businessadministration, was President of the ChemicalAssociation of Pittsburgh in 1992, and wasChair of the Symposium of EnvironmentalIssues in the Chemical Industry. She is a 4-year member of NACE.

LUKA MISKOVIC is a Major in the ArmedForces of the Republic of Croatia, Bavelova 33,Yagreb, 10,000, Croatia. He has 10 years ofexperience in the preservation of cannonarmanent.

TADIJI MADZAR is a Captain in the ArmedForces of the Republic of Croatia. He has 5 yearsof experience in the preservation of cannonarmament.

Corrosion leads to pin-hole leaks in the pipingof today’s fire sprinklersystems. Such systemsinclude: Wet pipe systems—The most common sys-

tems, these are used in buildings wherethere is no risk of freezing. Wet systemsare required for high-rise buildings andfor public safety.1

Alternative systems—As the namesuggests, the pipes of alternative systemscan be full of water for the summer andbe drained and filled with air under pres-sure for the winter. Alternative systemsare used in buildings that are notheated.1

Dry pipe systems—The pipes in drypipe systems are filled with air underpressure, and a control valve holds thewater back. When a sprinkler headopens, the drop in air pressure opensthe valve and water flows into the pipework and onto the fire. These systemsare used where the wet or the alternatesystems cannot be used.1

Deluge systems—These are used inspecial cases for industrial risks (e.g., off-shore oil rigs).

FM Global (Johnston, Rhode Island),a commercial and industrial property in-surer, inspected several fire sprinklersystems following reports of leakage vi-sually identified by building owners.2

The insurer identified leakage and re-lated encrustation and corrosion thatcould prevent the sprinklers from oper-ating as designed in the event of a fire.Often, a leak in the fire protection sys-tem is the only means of discoveringinternal corrosion problems.

Underwriters Laboratories, Inc. (UL)(Northbrook, Illinois) recently con-ducted laboratory tests on dry sprinklersystems taken from field installations.The test results indicated that exposingthese sprinkler systems to harsh environ-mental conditions over an extended pe-riod of time may render them inoper-able under certain fire conditions.3 In dry

Vapor PhaseCorrosion

Inhibitors ProtectFire Water Systems

ASHISH GANDHI

Corrosion is a problem faced by the fire sprinklerindustry in both wet and dry sprinkler system piping.

The ability of vapor phase corrosion inhibitors (VpCIs) toprotect fire water systems was tested in the laboratoryand field. The test results show that VpCIs provideprotection in the conditions present in wet and drypipe systems.

FIGURE 1

Vapor Inhibiting Ability test results for steel plugs in VpCI A.

systems, the problems go undetecteduntil the system fails to perform whenneeded in the event of a fire or until asystem inspection is made.

For a particular treatment programto protect fire sprinkler systems fromcorrosion effectively, the inhibitormust meet the following criteria: Prevent corrosion of systems manu-factured predominantly from ferrousmetals Prevent corrosion of systems com-posed of nonferrous alloys Have a low environmental impact Have low toxicity and skin irritabil-ity in case of contact with humans.

The corrosion protection propertiesof vapor phase corrosion inhibitors(VpCIs) were evaluated for dry and wetfire water systems. Laboratory testswere followed by field applications.

VpCI Treatment ProgramsRecent VpCI treatment programs

based on ambiodic inhibition (i.e., in-hibition at the cathodic and anodicsites) have been developed and evalu-ated in the laboratory. These treatmentprograms protect ferrous and nonfer-rous alloys by providing three-phasecorrosion protection as follows: In the water phase In the interphase, between waterand air In the air/vapor phase.

VpCIs have been used by automobilemanufacturers, the marine industry, andother environmentally sensitive indus-tries to meet stricter environmental regu-lations. Knowing the mechanism of cor-rosion protection and the fact that thenew generation of VpCIs are safe to useand have a low environmental impactwas a good starting point for evaluatingthe chemicals’ effectiveness in protect-ing fire water systems.

Corrosion and EnvironmentalLaboratory Testing

Two VpCIs—VpCI A and VpCI B—were evaluated in the laboratory. VpCI

TABLE 1

VIA TEST RESULTS FOR VPCI ASample Results(A)

Control FailVpCI A Pass(A)The test procedure contains pictures showing four grades of test results (0 to 3) with varyingdegrees of corrosion. Zero and 1 “fail”; 2 and 3 “pass.”

TABLE 2

FULL-IMMERSED AND HALF-IMMERSED RESULTS FOR VpCI BTime before corrosion (days)(A)

Metal Ambient Temperature (°C) 50°CCS 40+ 40+

CS(B) 40+ 20+

Copper 60+ 60+(A)Test samples are checked several times a day for onset of corrosion. The sample is considered “failed”at the first sign of corrosion.(B)Half-immersed test results.

A, made of amine carboxylates, was ex-amined in corrosion and toxicity tests.It was identified for use in dry and wetsystems involving ferrous metals. VpCIB, a blend of amine carboxylates andtriazole chemistry, was tested for corro-sion protection and skin irritability. (Be-cause VpCI B is based upon chemistrysimilar to that of VpCI A, costly toxicitystudies were not performed on this in-hibitor at the time of this study.) VpCI Bwas identified for use in dry and wetsystems involving nonferrous alloys. Al-though microbiologically induced cor-rosion (MIC) is one concern in fire wa-ter systems, these tests were devotedprimarily to general and pitting corro-sion. MIC historically has been ad-

dressed by using biocides. Biocides areeither used to sterilize the systems withshot treatments prior to filling the firewater systems or they are added withthe firewater.

CORROSION TESTSThe Vapor Inhibiting Ability (VIA) test

method4 was used to evaluate VpCI Awhile the Immersion and Half-ImmersionCorrosion test was used with VpCI B.

VIA TestIn the VIA test, the VpCI source

never comes in contact with the metalspecimen. A freshly polished steelspecimen was placed in a 1-L glass jarthat contained a measured amount ofwater blended with glycerin to controlthe relative humidity. A control sampleconsisted of a jar containing only a steelspecimen, while the test sample com-prised the jar with the steel specimenand VpCI A. After a conditioning pe-riod during which the VpCI vaporsmigrated from the source to the metalspecimens, the jars were placed in anoven set at 50°C for 4 h. The jars werethen placed at ambient temperatureand the metal specimens rapidlycooled; this led to condensation fromthe humid atmosphere. Effective VpCIcompounds provide protection in thisenvironment, while the control speci-men corrodes heavily. The test sampleswere run in triplicate. Table 1 presentsthe results for the VIA test. Following

In dry systems,

the problems go

undetected until the

system fails to perform

when needed in the

event of a fire or

until a system

inspection is made.

the conditioning period, VpCI Aprotected the steel specimen in themoisture-condensing environment.Figure 1 shows the appearance of theplugs at the completion of the test.

Immersion and Half-ImmersionCorrosion Test

Corrosion tests using VpCI B wereperformed on immersed and half-immersed carbon steel (CS) and cop-per panels at room temperature and at50°C.5 The CS panels were made fromcold-rolled steel (ASTM C10106)ground on both sides. The copper (CDA110) panels were sanded with 320-grit sandpaper. The panels and work-ing electrodes were washed withmethanol (CH3OH) prior to testing.Table 2 presents the test results.

ENVIRONMENTAL AND SKINIRRITABILITY TESTS

VpCI A was evaluated in bio-accumu-lation, biodegradability, and aquatic tox-icity tests. VpCI B was used in the skinirritability test, which was designed todetermine the dermal irritation poten-tial of the inhibitor on the shaved skinof a rabbit as required by regulation ofmedical device biocompatibility.

Table 3 presents the results of thebioaccumulation test. With a value ofthe partition coefficient (Pow) belowzero, VpCI A is unlikely to have toxiceffects on aquatic life over long timeperiods. The inhibitor’s quick biode-gradability, fully decomposing in <28days, also verifies its limited effect onthe marine environment.

TABLE 4

PRIMARY IRRITATION RESPONSE CATEGORIESResponse Category Comparative Mean Score (PII(A))Negligible 0 to 0.4

Slight 0.5 to 1.9

Moderate 2 to 4.9

Severe 5 to 8(A) The Primary Irritation Index (PII) is determined by adding the Primary Irritation Score for eachanimal and dividing the total score by the number of animals.7-10

TABLE 3

BIOACCUMULATION RESULTS (LOG POW) FOR VpCI A

Test Method Limit ResultOECD 117 log Pow < 3 < 0

Aquatic toxicity results showed thatVpCI A is not classified as an acute toxi-cant to primary producers (algae andaquatic plants), consumers (fish andcrustaceans), and sediment reworkers(seabed worms).

Table 4 shows the irritation re-sponse categories for the skin irritabil-ity test. At a working concentration of0.4% of VpCI B, the Primary IrritationIndex was 0—meaning that the inhibi-tor falls under a negligible responsecategory for skin irritability.

Case History:Field Corrosion Testing

A large oil and gas producing com-pany that operates several offshore andonshore installations was experiencingserious corrosion problems and nozzleblockages in the deluge fire water sys-tem. A unique method, using 5%-by-mass VpCI A concentrate solution as acorrosion inhibitor, was developed tosolve the company’s problem. A 19-mm predrilled plug was fitted at thejunction where the pipe work termi-nates. A fogging nozzle connected tocompressed air was inserted. Airflowwas established and a measuredamount of VpCI A concentrate was in-troduced into the amplified air stream.Wet fog emission through the sprinklernozzle was verified to ensure properapplication. This method of protectionwith VpCI A decreased blockednozzles by 97.6% within the first yearand 98.8% at the end of 2 years. UsingVpCI A dramatically reduced corrosion

problems for the operator over thespan of 2 to 3 years.

ConclusionsThe three-phase protection ability

of VpCIs allows them to be effectivein the conditions present in dry andwet fire water systems. Corrosion andtoxicity testing demonstrated that newVpCIs not only provide excellent cor-rosion protection but also have lowtoxicity. Skin irritability testing showedthat these compounds are safe for hu-man contact. As environmentallysound, safe, and cost-effective com-pounds, VpCIs are viable alternativesfor protecting fire sprinkler systemsfrom corrosion.

References1. British Automatic Sprinkler Association,

www.basa.org.uk.

2. News release, FM Global, www.fmglobal.com

(Feb. 8, 2000).

3. News release, Underwriters Laboratories, Inc.

(Jan. 22, 1999).

4. U.S. Federal Test Method Standard 101C,

Method 4031, “Corrosion Inhibiting Ability of V.C.I.

Vapors” (Washington, D.C.: U.S. General Services Ad-

ministration, 1980).

5. ASTM G31-72, “Standard Practice for Laboratory

Immersion Corrosion Testing of Metals” (West

Conshohocken, PA: ASTM, 1995).

6. ASTM C1010, “Standard Guide for Acceptance,

Checkout, and Pre-Operational Testing of a Nuclear

Fuels Reprocessing Facility” (West Conshohocken, PA:

ASTM, 1992).

7. ISO Standard 10993-10, “Biological Evaluation

of Medical Devices, Part 10–Tests for Irritation and

Sensitization” (Geneva, Switzerland: ISO, 1995), pp.

3-5.

8. U.S. Code of Federal Regulations (CFR) 16, Part

1500.41, “Method of Testing Primary Irritant Sub-

stances” (Washington, DC: Office of the Federal Reg-

ister, 1997).

9. F.N. Marzulli, H.I. Maibach, Dermatotoxicology

4th ed. (New York, NY: Hemisphere Publishing Corp.,

1991), pp. 201-208.

10. “Health Effects Test Guidelines,” U.S. Environ-

mental Protection Agency Office of Prevention, Pes-

ticides, and Toxic Substances (OPPTS) Report

870.1200 Acute Dermal Toxicity.

ASHISH GANDHI is the Water Treatment andMothballing Sales Manager at Cortec Corp., 4119White Bear Pkwy., St. Paul, MN 55110. He has achemical engineering degree from the University ofMinnesota and is a member of AIChE and NACE.

Originally developed toprotect boilers and pip-ing systems of ships tobe mothballed, thevolatile corrosion in-hibitor (VCI) has beenmodified over the years

to protect electronics, packaged items,reinforced concrete, coated metals, andmetalworking fluids.1-8 Innovations inVCI technology have generated a newclass of VCI chemicals that not only pro-vide excellent protection to metal sur-faces, but also protect the environment.In addition to being cost-effective, easyto apply, and durable, VCIs now are usedeffectively in environmentally sensitiveareas because they are nontoxic andnonpolluting. They also offer the advan-tage of not requiring preparation of themetal surface prior to use, eliminatingthe removal and disposal requirements

metallic structures. Protective vaporsdisseminate within an enclosed spaceuntil reaching equilibrium, which is de-termined by the partial vapor pressureof the VCI compound. The inhibitingprocess starts when the vapors contactthe metal surface and condense to forma thin film of microcrystals. In the pres-ence of even minute quantities of mois-ture, the crystals dissolve and developstrong ionic activity. This activity resultsin the adsorption of protective ions ontothe metal surface, with the concurrentformation of a molecular film that servesas a buffer and maintains the pH level atits optimum range (5.5 to 8.5) for corro-sion resistance.

VCIs were originally developed toprotect ferrous metals in tropical envi-ronments; however, recent develop-ments in VCI chemistry are based on thesynthesis of compounds that providegeneral protection (i.e., they protectmost commonly used ferrous and non-ferrous metals and alloys) (Figure 1).Electrochemical behavior investigationsshow that these VCI compounds belongto mixed or “ambiodic” inhibitors ca-pable of slowing both cathodic and an-odic corrosion processes. The reductionof the cathodic reaction results from adecrease in oxygen concentrationcaused by the formation of an adsorp-tion film that acts as a diffusion barrierfor oxygen. Strong inhibition of the an-odic reaction results from the inhibitor’stwo acceptor-donor adsorption centersthat form a chemical bond between themetal and the inhibitor. Adsorption ofmixed VCI compounds changes the en-ergy state of metallic ions on the surface,diminishing the tendency of metal toionize and dissolve.

The inhibition mechanism proceedsas follows:

Metal – R1 – Ro – R2

:Metal – R1 – Ro – R2

:Metal – R1 – Ro – R2

The functional group (R1), linked tothe nucleus (R0) of the inhibitor mol-ecule, is responsible for establishing astable bond with the metal surface andcontrols how firmly the inhibitor isadsorbed on the metal. The functionalgroup (R2), also linked to the nucleus,controls the thickness and penetrabilityof the film, which is important in resist

Cu Cd Mg AlZn

ControlAnodic InhibitorCathodic InhibitorBoth

FIGURE 1

Exposure of nonferrous metals to atmosphere containing VCI.

associated with pe-t r o l e u m - b a s e dproducts typicallyused for cleaning.

VCI ChemistryVCIs are a pow-

erful tool in com-batting atmo-spheric corrosionof metals and al-loys. Because theyare volatile at ambi-ent temperature,VCI compoundscan reach inacces-sible crevices in

EnvironmentallyFriendly VCIs

CHRISTOPHE CHANDLER AND BORIS A. MIKSIC, FNACE

Volatile corrosion inhibitors (VCIs) have evolvedover the years to serve as effective protection for

metals exposed to marine environments, chemicalprocessing, metalworking, and many other corrosiveconditions. This article discusses a new class of nontoxicand nonpolluting VCIs that can be safely used inenvironmentally sensitive areas.

ing the penetration of aggressive ions.As the inhibitor molecules are adsorbedon the metal surface, the R2 groups forma continuous line of defense to protectthe metal from corrosive species.

Active ingredients in VCIs usually areproducts of a reaction between a weak,volatile base and a weak, volatile acid.Such compounds, although ionized inwater, undergo a substantial hydrolysisthat is relatively independent of concen-tration. The independence contributesto the stability of the inhibitor film un-der various conditions.

The vapor pressure of the inhibitoris significant in achieving vaporizationof the compound. Too high a vaporpressure will cause the inhibitor to bereleased to such an extent that a pro-tective concentration cannot be main-tained. A low vapor pressure means theinhibitor is not used up as quickly, as-suring more durable protection. Addi-tional time is required, however, toreach the protective vapor concentra-tion; this leaves the metal exposed toincreased risk of corrosion during theinitial period of saturation. The vaporpressure of VCIs depends upon tem-perature (Figure 2). Controlled and de-pendable vaporization results from theproper selection of VCI compounds sothat the amount vaporized with tem-perature matches the kinetics of thecorrosion reaction. Higher tempera-ture increases a metal’s tendency tocorrode. Similarly, more inhibitivematerial evaporates at higher tempera-tures. VCIs can self-adjust to the aggres-siveness of the environment over awide temperature range.

Corrosion andEnvironmental Testing

A VCI identified as “VCI A” was usedin corrosion and toxicity tests. VCI A ismade of amine carboxylates. The lowerend of its melting point range is 188°C.

VIA TEST METHOD MEASURESVCI EFFECTIVENESS

The Vapor Inhibiting Ability (VIA)test method commonly is used to mea-sure the effectiveness of VCIs.9 It rap-idly assesses the protection offered byVCI products, which can be powders,liquids, or packaging products such aspapers or plastic films. Figure 3 illus-trates the VIA assembly used in testingthe VCI A compound. In this test, car-

3.7

3.9

4.1

4.3

3.36 3.40 3.44

2.2

2.3

2.4

The -log P (mm of Hg) of the vaporpressure as a function of 103/T (˚K).

- LO

G P

(mm

Hg)

103/T(˚K)

Dicyclohexylammonium nitrateCyclohexylammonium benzoateDiisopropylammonium nitrate

FIGURE 2

Dependence of saturated vapor pressure of VCIsupon temperature.

TABLE 1

VIA TEST RESULTSSample Results

Control Fail

VCI A Pass

A

B

C

D

E

F

B

TUBE

TEST SPECIMEN

ENLARGED VIEW OF “F”

A - Water retainer—Aluminum tube11.4 cm in length, 1.6 cm OD,and 1.3 cm ID. The tube shallhave a capacity of 16 mL distilledwater at 24° ± 2°C.

B - Rubber stoppers—Two No. 61.3-cm rubber stoppers with1.3 cm hole bored throughcenters.

C - Jar lids—Plastic screw-type lid,holes 3 cm drilled through centerwith two 0.6-cm holes 2.5 cmapart near the edge.

D - Jars—1-L size, mouth size6 cm diameter, 17.7 cm inheight, ID of 13.6 cm.

E - Insulating sleeve—1.3 cm IDrubber tubing, length 3.8 cm.

F - Steel specimen—1.6 cm OD,1.3-cm long with 0.9-cm deepflat bottom hole drilled in center(0.8 cm wall cup).

FIGURE 3

VIA test assembly.

bon steel UNS G1018 (Fed. Steel SpecQQ-S-698) plugs (1.6-cm diameter, 1.3-cm long) were polished with a 240-gritsilicon carbide (SiC) abrasive. Theabraded surface was then polished witha No. 400 aluminum oxide (Al2O3) pa-per at 90 degrees to the previousabraded marks. The plugs were cleanedwith methanol (CH3OH), allowed to airdry, and placed in a dessicator.

Ten mL of a synthetic glycerin-water solution—with a specific gravityof 1.075 at 24°C to create a 90% relativehumidity atmosphere—was introducedinto the bottom of the test assembly. Theinvestigators added 0.05 g of VCI A to adish, which was placed on the bottomof the jar. A lid was placed on the jarand tightened. The junction of theglass and lid was sealed with tape. Acontrol sample also was prepared, con-sisting of a jar containing only a steelspecimen.

The assembly was exposed to a tem-perature of 24°C for 20 h. Cold water ata temperature of 4°C below the ambi-ent temperature was added to the alu-minum tubes until they were full. After3 h, the water was removed from thetubes. The steel plugs were evaluatedfor signs of corrosion. In this testmethod, a visible change in the surfacefinish—such as pitting or etching—isconsidered corrosion. Stain alone doesnot indicate corrosion.

Table 1 pro-vides the VIA testresults. The con-trol plug showedheavy corrosion;however, plugsplaced in the pres-ence of VCI A hadno signs of corro-sion. Figure 4shows the plugs’appearance at theend of the test.

ENVIRONMENTALTESTING

Three environ-mental tests—bioaccumulation,biodegradation, andtoxic i ty—wereconducted on VCIA to determine itsimpact on the envi-ronment.

BIOACCUMULATIONBioaccumulation of substances

within aquatic organisms can lead totoxic effects over long periods of timewhen actual water concentrations arelow. The potential for bioaccumulationis determined by measuring the n-octanol/water partition coefficient ofa specific chemical compound. In test-ing the VCI A compound, the partitioncoefficient Pow was determined accord-ing to the Organization for EconomicCo-Operation and Development(OECD) Guideline test number 117[Partition coefficient (n-octanol/wa-ter), High-Performance Liquid Chroma-tography (HPLC) method].10

Table 2 shows the measured valueof POW. With a value below zero,bioaccumulation is unlikely.

BIODEGRADATIONBiodegradation is a measure of the

length of time over which a substancewill remain in the environment. Thebiodegradability of VCI A was deter-mined according to the OECD Guide-line test number 306,10 which is usedprimarily for biodegradation in marineenvironments. Chemical compoundsare subjected to a 28-day biochemicaloxygen demand (BOD-28) test. Degra-dation begins when 10% of the sub-stance has been degraded. Rapid deg-radation is evidenced when at least60% degradation of the substance isattained within 10 days of the start ofdegradation.

Figure 5 shows the 28-day BODvalue for VCI A. VCI A started to de-grade rapidly. It was 10% decomposedin <2 days. It was 76% degraded on Day7 and fully decomposed on Day 27. Tendays after the start of the degradationthe level of degradation had surpassed60%, indicating VCI A could be classi-fied as a rapidly degradable substance.VCI A fully biodegraded as its BOD-28value reached 100%.

AQUATIC TOXICITYAquatic toxicity testing is conducted

on organisms related to different levelsof the food chain, including primary pro-ducers, such as algae; consumers, suchas fish and crustaceans; and sedimentreworkers, such as seabed worms. Thetoxicity usually is assessed by determin-ing a 72- or 96-h EC50 for an algae spe-cies, a 48-h EC50 for a crustacean spe-cies, and a 240-h LC50 for a sedimentreworker. EC50 is the effective concen-tration of a chemical substance neces-sary to have a negative effect on 50% ofthe aquatic organism population. LC50 isthe effective concentration of a chemi-cal compound required to kill 50% of thepopulation.

The following tests were used to de-termine the aquatic toxicity of VCI A: Algae test—ISO/DIS 1025311 (fourthworking draft, “Water Quality—MarineAlgae Growth Test with Skeleto-nema costatum and Phaoedactylumtricornutum) test method Crustacean test—ISO/DIS 14669-9712 (“Water Quality—Determinationof Acute Lethal Toxicity to MarineCopepods”) test method Sediment reworker test—ASTME1367-9013 (“Standard Guide for Con-ducting 10-Day Static Sediment Toxic-ity Tests with Marine and Estuary Am-phipods”).

Tables 3, 4, and 5 present the resultsof the aquatic toxicity tests. Accord-ing to the OECD 306 test guidelines,10

the upper limit for acute toxicity mea-sured as 72-h EC50 is 100 mg/L in thecase of algae or other aquatic plants.The test results show that the 72-h EC50

for VCI A is 240 mg/L, indicating thatVCI A is not classified as a chronic toxi-cant. Similar results are shown for con-sumers and sediment reworkers.

CORROSION ANDENVIRONMENTAL TEST RESULTS

As the corrosion and environmentaltests demonstrated, VCI A protectsagainst corrosion while having no nega-tive impact on the environment. TheVIA test proved that VCI A could pro-tect a steel specimen in a moisture con-densing environment. The VCI sourcenever came into contact with the steelplug, showing that VCI A reached themetal surface via sublimation. The re-sults of the three environmental tests—low potential to bioaccumulate, quickbiodegradability, and no acute toxicityto aquatic specimens—showed the lowimpact of VCI A on the environment.

Environmentally FriendlyApplications

Environmentally friendly VCIs arebeing used successfully in arenas requir-ing nontoxic and nonpolluting chemi-cals, such as the marine and chemicalprocessing industries (Figure 6).

NORTH SEA USEA large Norwegian oil and gas pro-

ducing company operating several off-shore and onshore installations in theNorth Sea selected VCI technology asa cost-effective and environmentallyfriendly method of complying withstringent environmental regulations.

FIGURE 4

VIA steel plugs.

120100806040200

0 5 10 15 20 25 30

VCI A Sodium benzoate

Time (Days)

%

FIGURE 5

VCI A aerobic biodegradability.

TABLE 2

PARTITION COEFFICIENTTest

Method Result LimitOECD 117 log Pow <0 <3

The company eliminated the use ofan oil-water emulsion and its associateddisposal costs and cleaning require-ments, replacing it with VCI A forhydrotesting and preservation of inter-nal surfaces of pipes and vessels. VCIA is used on large pipe systems on off-shore platforms or smaller systems inrefineries or on onshore oil and gasreceiving stations.

VCI A was fogged inside the open-ings of recently hydrotested meteringstations (Figure 7) at a ratio of 500 g/m3. The ends were capped to seal theinstallation, protecting the units forextended periods of time until theywere dispatched and installed at theirfinal destinations. After hydrotesting,an aqueous solution (usually at a con-centration between 1% and 3.5%) ofVCI A powder was sent to a storagetank and used again or simply dis-charged into the sea. VCI A applica-tions also have been successfully usedon onshore pipelines and pig-launch-ing installations (Figures 8 and 9).

CHEMICAL PROCESSINDUSTRY USE

VCIs have been applied in a num-ber of chemical process industry ser-vices that involve enclosed atmo-spheres and require nontoxic andnonpolluting inhibitors. For largerequipment, such as tanks, boilers, andcondensers, VCIs are applied in bulkpowder form. The inhibitor vaporizesonce it is introduced into the enclo-sure. The protective film continuouslyrenews itself as the compound vapor-izes and the vapors condense. Thepowder is applied by misting and, onceapplied, the enclosure is sealed and noadditional measures (e.g., dehumidifi-cation, oxygen scavenging, etc.) areneeded for the entire period of protec-

TABLE 3

VCI A TOXICITY TO PRIMARY PRODUCERSExposure Effect

Concentration Time (h) Concentration (mg/L) Limit (mg/L)EC50 72 240 ≥100EC90 72 680 —No observed effect 72 32 —concentration

TABLE 5

VCI A TOXICITY TO SEDIMENT REWORKERSExposure Effect

Concentration Time (h) Concentration (mg/kg) Limit (mg/L)LC50 240 1,410 ≥100LC90 240 2,800 —No observed effect 240 1,014 —concentration

TABLE 4

VCI A TOXICITY TO CONSUMERSExposure Effect

Concentration Time (h) Concentration (mg/L) Limit (mg/L)LC50 48 100 ≥100LC90 48 220 —No observed effect 48 32 —concentration

FIGURE 6tion. In situations when it ispossible to seal the enclo-sure air-tight, the inhibitor isapplied by first evacuatingthe enclosure and then re-pressurizing it to allow thepowder to be drawn in.

The quantity of inhibitorneeded to protect a givenvolume can be calculatedfrom the following empiricalformula:

Q = 0.0277VC (1)

Where Q = total quantityof VCI powder, oz; V = vol-ume of the enclosure to be

VCI performance in industrial and marine atmospheres.

protected, ft3; and C = confidence fac-tor (2 to 3). The cost per unit of volumeper year is nominally $0.01 per ft3.

One or more VCI application de-vices in the form of a cartridge or tab-let can be used to protect smaller en-closures (e.g., in electrical andelectronic equipment). The device’schemical package usually contains amixture of inhibitors. It also may con-tain a fungistat to control fungalgrowth and a volatile buffer to create auniform pH on exposed metallic sur-faces. It often is difficult to determine

Metering station.

FIGURE 7

VCI Performance in Industrial and Marine Atmospheres

-------- All corrosion rates in mils/y -------

Metal No Inhibitor VCI Protected(A)

Aluminum (1000, 300, 5000 6000 series) 2.15 <0.25Mild Steel 21.8 <0.13HSLA (high-strength low-alloy steel) 1.2 0.08Naval Brass 0.2(B) 0.03Titanium 0.0(C) 0.0(C)

Stainless Steels: 410 0.01(D) 0.01(E)

304 <0.1(F) 0.01(G)

301, 316,and 321 0.0 (H) 0.0 (H)

Copper 0.22(F) 0.01(G)

Notes:(A) NI-22790 formulation (B) Dezincification (C) Immune to attack;no pitting or weight loss observed (D) Pitting (E) Pitting reduced(F) Staining (G) No staining (H) Free from pitting and weight loss.

FIGURE 8

Onshore pipeline installation.

FIGURE 9

Pig-launching installation.

References1. B.A. Miksic, P.J. Martin, Proc. 6th Euro-

pean Symposium on Corrosion Inhibitors

(Ferrera, Italy: 1985), pp. 941-950.

2. G.R. Sparrow, J. Proc, Symposium on Cor-

rosion Reliability of Electronic Materials and

Devices (Pennington, NJ: The Electrochemical

Society, 1984).

3. Y.C. Chang, B.A. Miksic, CORROSION/99,

paper no. 93 (Houston, TX: NACE, 1999).

4. B. Rudman, C. Chandler, Proc. EOS/ESD

Symposium (Orlando, Florida: 1996).

5. A. Groysman, CORROSION/98, paper no.

240 (Houston, TX: NACE, 1998).

6. N.N. Andrev, Y.I. Kutznetsov, CORRO-

SION/98, paper no. 241 (Houston, TX: NACE,

1998).

7. L. Gelner, CORROSION/98, paper no. 712

(Houston, TX: NACE, 1998).

8. G.R. Sparrow, C. Chandler, CORROSION/

95, paper no. 489 (Houston, TX: NACE, 1995).

9. Federal Test Method Standard No. 101C,

Method 4031 (1980).

10. OECD 117 Test Guidelines, Organization

for Economic Co-Operation and Development.

11. ISO/DIS 10253, “Water Quality—Marine

Growth Test with Skeletonema costatum and

Phaoedactylum tricornutum” (Geneva, Swit-

zerland: ISO).

12. ISO/DIS 14669-97, “Water Quality—De-

termination of Acute Lethal Toxicity to Marine

Copepods” (Geneva, Switzerland: ISO, 1997).

13. ASTM E1367, “Standard Guide for Con-

ducting 10-Day Static Sediment Toxicity Tests

with Marine and Estuarine Amphipods” (West

Conshohocken, PA: ASTM, 1990).

CHRISTOPHE CHANDLER is the LaboratoryDirector at Cortec Corp., 4119 White BearPkwy., St. Paul, MN 55110. He has worked inthe field of corrosion science for the past 12years and has developed more than 30 productsand systems that use vapor-phase corrosioninhibitors and VCIs. Chandler has a Ph.D. inmaterials science and has authored orcoauthored seven U.S. patents. He is a 12-yearmember of NACE.

BORIS MIKSIC, FNACE, is President of CortecCorp. He has developed more than 300products and systems that use vapor corrosioninhibitors. He has an M.E. from the University ofZagreb, is a NACE Fellow, and has been aNACE member for 28 years.

the exact number of VCI devicesnecessary for protection because of thevarious shapes and sizes of enclosuresand the varying conditions of storage.Typical devices protect a 1- to 40-ft3

(0.03- to 1.13-m3) volume for 2 years.The actual number of devices neededto achieve saturation of vapors in a spe-cific period of time and to maintain thatsaturation for 2 years is conventionallydetermined by the following equation:

N = (ka)(kp)(ks)(No) (2)

Where N = numberof devices needed toprotect a given volumeunder specific condi-tions; ka = factor ex-pressing the corrosive-ness of the environ-ment; kp = factor ex-pressing frequency ofopening or breath-ability of the enclosure;ks = factor expressingthe shape of the enclo-sure; and N0 = numberof VCI devices that arebased on nominal vol-ume of protection.

VCIs offer the chemi-cal processing industryeconomic and proce-dural advantages. It isnot necessary to pre-pare the metal surfaceprior to using VCIs be-cause their vapors canpenetrate to remote ar-eas of an enclosure.Using VCIs also reducesthe requirement to rig-idly plan maintenanceschedules because thecompounds can protectdissimilar metals andperform in severe envi-ronments.

ConclusionsVCIs are used in a wide range of situ-

ations where atmospheric corrosiondamages exposed metals, including en-vironmentally sensitive marine environ-ments and the chemical processing in-dustry. In addition to providingexcellent corrosion protection and lowtoxicity levels, VCIs are cost-effectiveand long-lasting.

MCI®, VCI, and VpCI Literature Research IndexAircraft Cost Savings Corrosion Protection for DeepStorage and Preservation of United States AirForce Vehicles and EquipmentA.M. Vignetti, CORROSION/2001 paper no.559, NACE: Houston, TX.

Environmentally Friendly CorrosionProtection in Cleaning Systems for United StatesCoast Guard AircraftC. Cracauer, CORROSION/2001 paper no. 560,NACE: Houston, TX.

Preservation of U.S. Air Force Vehicles andEquipmentA.M. Vignetti, Cortec Supplement to MP 40, 1,2001.

Coatings Volatile Corrosion Inhibitor CoatingsM. Prenosil, Cortec Supplement to MP 40, 1,2001.

Electronics Vapor Corrosion Inhibitor Field Applicationsin ElectronicsB.A. Miksic, A.M. Vignetti, Cortec Supplementto MP 40, 1, 2001.

Vapor Corrosion Inhibitors: Successful FieldApplications in ElectronicsB. Miksic and A. Vignetti, CORROSION/2000paper no. 707, NACE: Houston, TX.

The Application of Vapor Corrosion Inhibitorin the Storage of Metal-Particle MagneticRecording MediaAmpria Research & Design: MN, 1996.

Volatile Corrosion Inhibitors for ElectronicMaterialsS.T.Z. Tzou, B.A. Miksic, The ElectrochemicalSociety: Pennington, NJ, 1990.

Metal Protection An Investigation into the Inhibition ofDifferent VCIs for the Protection of Aluminum2024 in the Presence of H

2S and SO2

P. Jaeger, L.F. Garfias-Mesias,W.H. Smyrl,CORROSION/98 paper no. 234, NACE:Houston, TX.

Migrating Corrosion InhibitorsTM (MCI®) MCI Protection of ConcreteD. Bjegovic, B.A. Miksic, Cortec Supplement toMP 40, 1, 2001.

The Investigation of the MCI Effectiveness onRandolph Street BridgeD. Bjegovic, R.D. Stehly, S. Matuzic, J. Jackson,EuroCorr 2001: Lake Garda, Italy, 2001.

Testing Migrating Corrosion Inhibitors forReinforcement ProtectionD. Bjegovic, B.A. Miksic, R.D. Stehly,9th European Symposium on CorrosionInhibitors, University of Ferrara CorrosionStudy Centre: Ferrara, Italy, 2000.

Migratory Corrosion Inhibitors for CorrosionControl in Reinforced ConcreteM. Forsyth, A. Phanasgaonkar, B. Cherry,9th European Symposium on CorrosionInhibitors, University of Ferrara CorrosionStudy Centre: Ferrara, Italy, 2000.

Testing Methodology for Migrating CorrosionInhibitorsD. Bjegovic, B.A. Miksic, EuroCorr 2000,London, U.K.

Topically Applied Migrating CorrosionInhibitors of Reinforced Concrete ProtectionD. Bjegovic, B.A. Miksic, EuroCorr 2000:London, U.K.

Migrating Corrosion Inhibitor Protection ofConcreteD. Bjegovic, B.A. Miksic, MP 38, 11, 1999.

Test Protocols for Migrating CorrosionInhibitors (MCI®) in Reinforced ConcreteD. Bjegovic, B.A. Miksic, R. Stehly, Materialsand Corrosion Magazine, December 1999.

Calculation of Diffusion Rate of MigratingCorrosion Inhibitors Through ConcreteD. Bjegovic, D. Mikulic, D. Krstic, CONSEC:Norway, 1998.

Compatibility of Repair Mortar with MigratingCorrosion Inhibiting AdmixturesD. Bjegovic, V. Ukrainczyk, B. Ukranczyk, B.A.Miksic, CORROSION/97, paper no. 183, NACE:Houston, TX.

Migrating Corrosion Inhibitors for ReinforcedConcreteA. Eydelnant, B.A. Miksic, L. Gelner,ConChem Journal, 2, 1993.

Military Successful Corrosion Protection Utilized byMilitary WorldwideA.M Vignetti, CORROSION/2001 paper no.561, NACE: Houston, TX.

Weaponry Conservation: Volatile CorrosionInhibiting Packaging Field ResultsB. Rudman, P. Piacun, CORROSION/98, paperno. 602, NACE: Houston, TX.

Vapor Phase Corrosion Inhibitors for NavyApplicationsK.L. Vasanth, C.M. Dacres, CORROSION/97,paper no. 179, NACE: Houston, TX.

Corrosion Inhibition in Naval VesselsK.L. Vasanth, CORROSION/96, paper no. 233,NACE: Houston, TX.

Packaging Advances in Biodegradable CorrosionProtection PackagingC. Chandler, CORROSION/2002 paper no. 322,NACE: Houston, TX.

Use of Corrosion Inhibitors in GlobalShipping of Electronic EquipmentC. Chandler, CORROSION/2001 paper no. 562,NACE: Houston, TX.

A Packaging Concept for the New Millen-niumB. Miksic, R.W. Kramer, Cortec Supplement toMP 40, 1, 2001.

Environmentally Friendly MultipurposeGrease Resistant VCI SystemB.A. Miksic, E. Chang, CORROSION/2000paper no. 336, NACE: Houston, TX.

Corrosion Control Packaging Film Preparedfrom a Biodegradable Compostable ResinC. Chandler, A. Ahlbrecht, B.A. Miksic, 4th

Annual Green Chemistry and EngineeringConference, ACS: Washington, D.C., 2000.

Stretch Packaging—It’s a WrapB.A. Miksic, R.W. Kramer, Steel Times 227, 5,1999.

Environmentally Friendly VCI SystemsY.C. Chang, B.A. Miksic, CORROSION/99 paperno. 93, NACE: Houston, TX.

VCI Technology for Flat Rolled SteelProductionB.A. Miksic, R. Kramer, A. Sobkin, AISE: PA,1998.

Surface Chemistry A Methyl Soya-Based Cleaner and CorrosionInhibitor SolutionC. Chandler, M. Kharshan, M. Lowe, 4th

Annual Green Chemistry and EngineeringConference, ACS: Washington, D.C., 2000.

The Role of Surface Chemistry and VCIs inEarly Stages of Metal ProcessingG.R. Sparrow, C. Chandler, CORROSION/95paper no. 489, NACE: Houston, TX.

VCIs and Corrosion Basics Biodegradable Volatile Corrosion Inhibitorsfor Offshore and Onshore InstallationsC. Chandler, MP 40, 2, 2001.

Environmentally Friendly Volatile CorrosionInhibitorsC. Chandler, CORROSION/2001 paper no. 194,NACE: Houston, TX.

Storage Tank Bottom Protection UsingVolatile Corrosion InhibitorsA. Gandhi, Cortec Supplement to MP 40, 1,2001.

Development of Reinforcement CorrosionInhibitorsD. Bjegovic, B.A. Miksic, R.D. Stehly, 79th

Annual Meeting and International CoatingsTechnology Conference, Edinburgh, U.K.,Institute of Corrosion: Bedfordshire, U.K.,2001.

Test Methods for Vapor Corrosion InhibitorsA. Furman, C. Chandler, 9th EuropeanSymposium on Corrosion Inhibitors,University of Ferrara Corrosion Study Centre:Ferrara, Italy, 2000.

Pre-testing the Effectiveness of CorrosionInhibitors by Accelerating MethodD. Bjegovic, B.A. Miksic, EUROCORR 1999,DECHEMA: Frankfurt, Germany.

A Comparison of Several Corrosion InhibitingPapers in Various EnvironmentsB. Rudman, CORROSION/98, paper no. 237,NACE: Houston, TX.

A Procedure for Testing the Effect of VaporPhase Corrosion Inhibitors on Combined MultiMetalsC. Kraemer, CORROSION/97, paper no. 178,NACE: Houston, TX.

Instrumentation for Measurement of theEffectiveness of Vapor Corrosion InhibitorsC.G. Moore, B.A. Miksic, CORROSION/95,paper no. 490, NACE: Houston, TX.

Water Treatment/Process/Chemicals Use of VpCIs (Vapor Phase CorrosionInhibitors) For the Protection of Fire WaterSystemsA. Gandhi, CORROSION/2002 paper no. 320,NACE: Houston, TX.

Lay-up of Cooling Towers and Boilers withVolatile Corrosion InhibitorsA. Gandhi, B. Miksic, CORROSION/2001 paperno. 487, NACE: Houston, TX.

Water Treatment ApplicationsA.Gandhi, Cortec Supplement to MP 40, 1,2001.

Biodegradable Volatile Corrosion InhibitorsC. Chandler, 9th European Symposium onCorrosion Inhibitors, University of FerraraCorrosion Study Centre: Ferrara, Italy, 2000.

Volatile Corrosion Inhibitors—Unique WaterTreatment ApplicationsA. Gandhi, The Analyst, Fall 2000.

Incorporating Vapor Corrosion Inhibitors(VCIs) in Oil and Gas Pipeline AdditiveFormulationsM. Kharshan and A. Furman, CORROSION/98paper no. 236, NACE: Houston, TX.

Methodology of VCIs for Water TreatmentA. Furman, M. Kharshan, CORROSION/97,paper no. 182, NACE: Houston, TX.

Protection of Storage Tank Bottoms UsingVolatile Corrosion Inhibitors (VCI)L. Gelner, NACE Middle East RegionalConference, 1996.

VCIs—A Novel Approach to CorrosionControl in the Water Treatment IndustryC. Chandler, A. Furman, M. Kharshan,WATERTECH, 1995.