ADYANCAS IN HIGH PRODUCTION ROBOTIC WATER-JETTINGFOR THE MARIN-E INDUSTRY

John Odwazny, Sr. Vice President - Ultrastrip Systems, Inc., Stuart FloridaCarlos Da Maia, Managing Director - Tecor, Lisnave Portugal

Gordon Kuljian, VP. Operations - Chemstar Urethanes - Contributing Author

Prepared for Shiprepair & Conversion 2001

Abstrac* Significant technological advances in water-jetting equipment design have provided shipyaxds, owners,and operators a means of achieving high production hulltreatment in addition to selective coating removal down toindividual layers of paint for large marine structures, suchas ships decks, vertical sides, and bottoms. This paper willzummarize the evolution and growth of automated andsemi-automated water-jetting machinery for surfacepreparation and the role they will play in the future.

BRIET'HISTORY

Most large ocean-going vessels, whether they be crude oiltankers, bulk cargo ships, military, Coast Grard, orchemical tankers, generally have hull plating that is madeup of steel which is protected by layers of anti-corrosive(usually epory) and anti-fouling coatings. Over time, suchcoatings succumb to failure modes of differing varieties.These coating systems must be renewed, either partially ortotally. Historically, traditional surface preparation andcoating renewal work has been a low tech, labor and timeintensive, environmentally challenging endeavor, itunfortunately has been an unavoidable part of shipmaintenance. The all too familiar process of abrasive gritblasting removed coatings. This technology, althougheffective in coating removal and establishment of surfaceprofile, is laden with inherent problems, many of whichhave been documented throughout the mid-1980's to thepresent. The most common of shipyard blasting problemsinclude:

blasting

airborne particulate (lead and chromate laden dust)

of blasting

and prior to painting

1

For decades, ship repairers and ship builders haveexperimented with alternatives to grit blasting. Suchalternatives introduced in the earlyto-mid 1980's rwolvedaround centrifugal shot blasting machinery that wasmechanically hoisted (via high lift) or suspended (via steelcabling) and afiixed to the vertical side shell of a ship viaerdernal pressure and vacuum attachment. The vasuumaided in producing a clean surface, whereby shot and wastewere classified and cleaned, with the cleaned shot being re-introduced as the cleaning medium. Such devices wereeffective means of surface preparation and showed muchpromise, however never became popular in the ruggedenvironment of a shipyard. Into the 1990's, U.S. yardsbegan realizing the human and environmentalconsequences of open-air blasting; many yards eitherenclosed portions of the ship and dry doclq to containdebris, or affixed a mini-traveling containment to performblasting. Such technologies are still in use today.

Slurry BlastingCertain yards, zuch as the U.S. Navy's Trident RefitFacility in Bangor, WA began realizing the value of waterfor shipyard blasting. Beginning in 1993, TRFincorporated slurry blasting into their operations to removeepoxy containing lead and anti-fouling coatings containingcuprous oxide. (Slurry blasting involves pressurized airpropelling a gdt and water stream to remove the coating,while suppressing dust.) The TRF approach incorporatednot only water, but also a blasting additive (to render leadnon-hazardous) as well as rust inhibitors to suppress flashrusting prior to coating. Their experiences were positive inremoval of airborne dust, rendering of over .75M poundsof debris non-hazardous, atl while blasting withoutconstructing containment. To date, U.S. Navy west coast-based; 560 ft. long strategic ballistic missile submarineshave been blasted using water and gnt. This method hasbeen documented by the Navy to conzume 20o/o of grrtconsumed by straight abrasive blasting. A joint studyauthored by the TRF and Puget Sound Naval Shipyardnoted that when compared to open air abrasive blastingwith containment, their slurry method cost 19.5% ofabrasive blasting , on a $/ftz basis. t

Water ShrpudsA different approach in 1994-1995 was incorporated by the(then) Philadelphia Naval Shipyard. The aircraft carrierJOHN F. KENNEDY was entering dry dock. Her hull wascovered with a tributyl-tin (TBT) oxide containing anti-fouling coating. After the Congressional OrganotinAntifouling Paint act of 1988, the Navy took the lead inremoval of such a toxic coating from the few hulls thatcontained it. PNSY incorporated a water shroud overconventional blast nozzles, which eliminated airborneexposure to the dangerous TBT-containing coating. Theentire dry-dock floor had to be lined with an impermeablemembrane, ild the slurry Gdt/paint residue) had to becollected and disposed of Although the water slroudseliminated the need for dry dock containment, and reducedairborne exposure to dust, the problem still remained forwaste oollestion and disposal.

Water-Jetting (NSRP Study)

NOTE: Water-jetting is described as a means of coatingremoval using solely water at over 25,000 p.s.i. pressure.Water-jetting has generally been known for its ability toleave its surfaces ultra-cleaq without distorting orimparting additional profile to the substrate.r

At about the same time the KENNEDY job was beingplanned, water-jetting was being introduced, mostly on ademonstrstion basis, to many shipyards throughout thecountry. Shipyard representatives, realizing the increasingpressures from environmental restrictions (airbornedischarges, storm-water discharges, disposal costs forgrit/paint) felt it necessary to explore water-jetting for ameans of coating removal more closely. The NationalShipbuilding Research program commissioned a study onthe feasibility and effectiveness of water-jetting for theship repair and ship building marketplace. Results of thestudy were pubtished in 1998 2' and summarized in lggg3.

The study included an in-depth examination of over ten de-painting efforts on ships and offshore platforms, whichutilized water-jetting as the sole means of surfacepreparation. Scenarios included removal of underwater hull,freeboard, ballast tanlq and non-skid deck coatings. Shipavailability included new construction and maintenance.Many unknown parameters about water- jetting werequantified during the study such as:

and "spot and sweep" removal (see Table 1)

(remaining on existing coating)

The overwhelming feeling of the authors was that a widevariety of situations are ideal for water-jetting, such as:

systems

of anti-fouling while keeping epoxy anti-corrosivelayers intact

construction.

THE INIRODUCTION OF AUTOMATION

The majority of water-jetting in shipyards in the 1995-1998timeframe involved open cycle "men on guns" type ofwater-jetting. However, as part of the study, recentlyintroduced semi*automated, and semi-robotic machinerywas observed removing a variety of coatings. The USNavy developed a drydock floor mounted system, attachedto the end of a 60 ft. high reach which removed a 25 ffpatch of coating at one time prior to repositioning. Allmaterial is vacuumed away from the surface and filteredand treated in a water reclamation trailer, where the wateris reintroduced as jetting water into the pump$. Suchtechnology, although low productiorq is truly "closed loop"aoating removal, with the only waste being the paint chipsthemselves. (This machinery is described in full in atechnical article.a ) At this same time (1996) the paralleldevelopment of the magnetically adhering robotictechnology was taking place In late 1997, a U.S.company, in tandem with a specialty water-jettingcontrastor introduced a vacuum attached open circuitcrawleq which removed an ll-inch coating path using arotating nazzle. The waste stream was vacuumed awayfrom the surface where the heavy solids were separatedfrom the water, the water stream was diverted to a holdingtank where it could be analyzed prior to fieatment ordisposal. The effectiveness of the vacuum crawler type ofmachinery was demonstrated on several hull coatingremoval trials, due to its maneuverability and lack ofhuman involvement (zuch as with "men on guns".)

Such machinery, although not used by many shipyards andcontractors at the time, clearly demonstrated manyadvantages over simple human driven removal such as:

free of flash rusting or other contaminants

particulates or water droplets (containing haeardousmaterial)

unintemrpted

personnel

lancing with water

acoidents by the operator

To quote the NSRP study (concluded in 1997):

"It is thc opinion of the authors thatfor large scale, quickturnaround coating removal on a ship's underwater lruIl orfreeboard, the automated or semi-automated roboticmachinery that contains all blasting water and efiIuentrepresents the most promise for the ship repair indastry.These machines can fficiently remwe coatings down tothe origirnl wbsffate without the fear of fiIash rusting andpr ovide exce llent wrface s for imme diate r e coating. "3

THE STATF-OF.THE ART

Since the introduction of semlautomated and roboticmachinery, facility owners willing to explore new avenuesin surface preparation have greatly benefited from theinnovative features that the manufacturers have to offer.Several ultra high pressure pump manufacturers, who atone time only offered jetting lances and specializedcutting/hydro-demolition equipment, now offer roboticcrawler-type dwices for large area vertical and horizontalsurface preparation. A review of the available machineryhas been documented in recent articles 5f and all tend to beunique in their own way. Methods of attachment of theautomated machinery are ofilered by vacuunq attachment tothe end of a telescopic arm (of a man-lift), attached to adry-doclq or attachment by magnets. A few case historiesof robotic and semi-automated machinery for coatingremoval will be summarized.

Shipboard Deck Coatin&RemovalThe United States Navy currently owrrs and operates 13fighier-jet capable aircraft carrieis. The most modern ofsuch massive vessels measure over 1000 ft. in length,displace over 95,000 tons of water at full load. Each carriercontains over 300,000 ftz of thick epoxy deck coating.(This "non-skid' deck coating consists of t0-12 milsepoxy/polyamide primer layers followed by a thixotropicepo)ry matrix filled with either aluminum metal oraluminum oxide.) This tough slip resistant coating needsto be removed and renewed periodically, depending onsenrice location (landing area, run-out area, weather declqhangar bay).

Traditionally, only recyclable abrasive shot blasting hashad the impact power to shatter the non-skid for removal.Such technology is very effective in removing the coating,and achieving zurface profiles in excess of 4.0 mils while

providing an SSPC-SPS White Metal surface. Theineffrciency of the shot blasting machinery to completelycontain all the blast media has routinely caused countlessman-hours of clean up of the shot media from the declgaircraft elevators, catapults and deck machinery. (Suchclean up is imperative to avoid potentially fatal accidentsdue to foreign object damage-F.O.D). For this reason" inaddition to the potential for higher productivrty and cleanersurfaces, the US Navy seriously began to explore the useof automated machinery on the decks of its vessels in 1997on the USS CARL VINSON (CVN-70). After othersuccessful demonstration projects, 200,000 ft' of coatingwere removed from the flight deck of USS CTEORGEWASHINGTON, and in ldarch 1999,200,000 ft2 of non-skid were removed from the deck of USS DWIGHT D.EISENHOWER. The EISENHOWER job wasaccomplished in a period of 40 days using 4 semi-automated vacuum attached robots, during an extendedmaintenance period for the ship. Such robots have an 11-inch cutting patb contained within the vacuum shroud.

Higher production-oriented machinery, such as 24-inchand 48 inch cutting swath machines, and rotafing headsmounted on articulating Oack and forth) arms have beenintroduced by other domestic companies. The Naval SeaSystems Command tested such machines two years later onthe EISENHOWE& when the deck coating neededrenewing. Two contra,ctors were commissioned tocomplete approximately 200,000 ft2 of fligtrt deck non-skidremoval. One contractor employed six vacuum attachedsemi-automated crawlers, e>ractly the same as on the 1999removal. During unintemrpted production runs, suchmachines were observed to cr$ traditional non-skid at 350+ft2 /hour. The other contractor deployed one 24" robot, andone 48" robot. Also demonstrated were 2 differentarticularing head robots. Total production numbers over a1S-day period are listed in Table 2.

Each contractor completed approximately 100,000 ft2 ofnon-skid removal in approximately 2 weeks. Never beforehad an aircraft carrier had its deck coating completelyremoved and primed in such a short time. The coltractorshad to work through harsh mid-Atlantic United StatesFebruary/Ivlarch weather, coupled with shipyard tradesloading equipment onto the deck of the ship in preparationof an extended maintelance period. All water and non-skid debris was evacuated into settling tanks, andwastewater was oFloaded daily. The benefits of theproject were unprecedented to the Navy:

cleanliness requiremerts

potential

The Naval Sea Systems Command in Washington, DC,which distates technical policy for new construction andmaintenance of its ships, has enthusiastically endorsedrobotic ultra-high pressure water-jetting of its flight decknon-skid. Shipyard and contrastor process instructions arein-place and a^re common documents used in biddingcontracts for Navy work. To-date over 4,000,000 ft2 ofnon-skid coating have been removed from the flight declaof US Navy Vessels using automated ultra-high pressurewater-j etting technology,

Shipboard Outer Hull Coating Removal {USS C.OLETAs with deck coatings, the use of ultra high pressure waterjetting GfWI) to remove outer hull (underwater hull andfreeboard) coating systems has become increasinglypopular among ship operators. Beginning in 1998, suchowners, particularly the US Navy, have hired contractorpersonnel equipped with vacuum attached crawler robotsto remove outer hull coatings. The general consensusamong owner, contractoE and shipyard personnel is thatsuch machinery is a welcome improvement to abrasiveblasting or full dry dock containment for reasons citedabove. Production rates of the machinery may vary, butone can generally state that maximum production rates forsuch devices can strip a typical underwater hull coatingsystem (military) at a rate of 250-325 ft2lhou. Such ratesare superior to^ one man on an abrasive blast noz.zle,averaging 100 ft"/hour.

Up until the year 2000, the skid steer vacuurn adheringcrawling unit with an open circuit waste discharge vacuumbag filtration was the state-of-the-art equipment forcommercial coating removal using UI{PWJ.

The Ultrastrip System's patentd magneticatly attachedrobof designed for selective layer, spot, and full coatingremoval was introduced at this time. This technology,branded the M-2000 series, capitalized on high-speed, freecrawling maneuverability, with an ability to ultra-filtrateand close loop all wastewater. This unit cuts a L5" path ofcoating to bare metal. USS COLE (DDG-67), a 504 ft.guided missile destroyer, was in dry-dock at Litton/IngallsShipbuilding in Pascagoula, MS (the new constructionyard for the *COLE') undergoing massive repair after aterrorist incident while anchored in the port of Yemen inOctober 2000. NaW and Litton/Ingalls representativeschose to test the M2000 non-polar magnetically attachedtechnology for a number of reasons:

1. Quick turn-around of repainting of underwater andfreeboard hull was needed

2. Elimination of airborne dust was desirable in ashipbuilding environment

3. Such a process was seriously being considered forfutr"rre new construction and repair efforts.

In a period of 9 days, one lvl2000 series magnetic unitstripped 23,212 ft' of an underwater hull and freeboard(above waterline) hull coating system measured to beapproximately 25+ mils and 3l+ si1t, respectively (seeTable 3). The robotic unit stripped an average of 2586 ft2/day over the 9 day period; however rarely was the robotstripping in an uninternrpted mode, due to shipyardobstacles. Realistic timing data was obtained periodicallywhere the unit stripped the underwater hull coating systemto Near White (WJ-2, I{B-2.5) metal at a rate af 720 ftz /hr.Such rates are typical for this particular machinery. Thespeed of the M2000 technology allows for high-speedmaneuverability around obstacles and easy realignment ofthe cutting path for the operator. Vacuum attached crawlertechnology by the physical nature of adhesiorq althougheffective, cannot move along the hull with such speeds.

The LittoMngalls personnel had the contractors test theM2000 equipment on an adjacent cruise vessel underconstrustion to determine the rate of sweep blasting of thepre-construction primer (PCP). Their newbuildingspecifications called for aNear White Metal (SSPC-SP-l0)blast of the outer hull PCP (a tenaciously adhered solvent-born inorganic zinc silicate coating applied at nominally1.2 mils DFT). The robot was able to sweep offthe PCP tothe specified SP-10 finish at a rate of 2250 fnr. Evenmore impressive is the speed of travel of which the robot iscapable of. At a top speed of travel of 2A inches/second,the robot is able to dwell on one area of concenq andquickly traverse to another are4 prior to performing ahigh-speed sweep. Movement at such speeds is notpossible by the limiting factors of vacuum attached robots(due to the speedJimiting nature of suction attachment).The versatility of specialized magnetic robots make themideal for "spot and sweep" blasting operations, themaintenance *norm" in many global shipyards.

Closed-Loop lJltra FiltrationThe ability of water-jetting equipment to be able to treateffluent on-site and re-introduce the filtered pure water tothe ultra-high pressure pumps has not been routinelypracticed in the field. Contractors may typically filter largeparticles frorn the effluent, and o$load wastewater fromthe dry-dock for subsequent analysis and disposal. Theability to eliminate the large volumes of wastewater, byutilizing an ultra-filtration package, as demonstrated on the"COLE', is of enormous benefit to the facilif owner froman economio, as well as environmental standpoint. Thefiltration trailer utilized on the "COLE' is housed in asound proo{, temperature controlled, 40' overseas shippingoontainer, and incorporates a 5 step filtration process:

STEP 1: Centrifugal Separation - Separates water frompaint fragments

STEP 2: Media Filtration- Removes particulates down to5 micron in sizeSTEP 3: Activated Carbon Filtration - Removes metals(including Tri-butyl tin compounds) and RCRA heavymetalsSTEP 4: Illtra Filtration - Removes particles from .003micron - .02 micron in sizeSTEP 5: Reverse Osmosis Filtration - Removes chloridesand other molecular species contributing to increasedconductivity ofthe jetting water.The capacrty of the unit is 26 gallons per minute, easilyhandling up to two 12 GPM pumps feeding two roboticjetting units.

M2000 Technology in Lisnave ard the FPSO Conversio.r.r"Jamestown"

The Ultrastrip technology was used on the recent I|PSOconversion of the "Jamestown" in Lisnave. The results ofthis project conclusively demonstrated that patentedM2000 UIIPWJ technology outperformed conventionalsandblasting and non-magnetically attached devices in allareas (speed, efiiciency, and qualrty of blast). The "James

town" was the first vessel in Lisnave to have theunderwater hull and topsides af,eas treated with a UIIPWJrobotic denice. This vessel was in lay up for eidnt yearsbefore entering the dock with an excessive build-up of hardmarine growth on the underwater hull consisting ofencrusting corals and barnacles. Hand scraping removedthe high profile growtb however encrusting coralsremained on the surface of the underwater hull during theUIIPWJ operation. The surface preparation for the "James

Town's" topside's (tLL to Maindeck) called for firUsweeping (SA1.0 / WJ4). The underwater hull specified atotal coating removal (SA2.0 WJ3 fninimum).

High Speed Sw.eepingThe Id2000 technology will achieve a maximum sustainedfree crawling traverse speed over unobstructed areas of20in.-48 cm./sec. This traverse speed is achieved tlroughthe combination of a highly sophisticated drive train and apatented proprietary method of non-polar magneticattactrmerrt. The speed of the robot is precisely controlledwith one radio controlled driver. The robot operatorcontrols the cutting jet head height adjustment, traversespeed of the robog and pump pressure. Depending uponthe thickness of coatings that requires removal, the M2000operator can accurately adjust the energy delivered to thesurface along with the robot speed to achieve the desiredresults. Micro adjustments with both the traverse speedand cutting head height provide unparalleled flexibility instripping operations. Old broken down topside finishes andharmful underwater hull organotin antifoulings may bezuccessfully removed down to intact anticorrosives withoutdamaging costly basecoats.

The M2000 robotic technology successfufiy removed onlyeffected broken down topcoatings from the "Jamestown'.

The underlying epoxy anticorrosive was left intact andundisturbed by the UHPWJ process. The "Jamestown" wasa significant event as it demonstrated that high speedUIIPWJ sweeping of surfaces can be accomplished in avery precise cost effective manner.

rUfl]RE TRENDS

MarineTrue robotic and semi-automated machinery has gainedfavor between yards, contrastors, and owners in achievinga superior quality product while maximizing worldorceefficiency. Implentation of this technology has beenparticularly active in the marine industry. The stripping ofpaint and corrosion control of outer hulls and decks ofships is a significant investment by owners. Source pointcontrol and ultra filtration of the pollution stream arealready being considered by the world's largest ship repairyards as the entire international shipping communitybraces for January 1, 2003, when the InternationalMaritime Organization enacts the global treaty prohibitingthe use of organotin TBT's (tributyl-tin) containing anti-fouling coatings. The draft treaty includes the following,in summary:

containing anti-fouling coatings on worldwide ships

containing anti-fouling coatings in contact with seawater on worldwide ships.

What this means to the ship-owner is that by January 2008,any vessel must be free of all TBT coatings or risksubstantial fines, according to (future) maritime law.7What this means to the ship yard is that if owners rush tohave their hulls stripped and cleansed of zuch coatings,"ho$t" shipyards will be required to undertake such workin an environmentally responsible manner, i.e. beresponsible for the wastewater and hazardous antifoulingbyproducts. Ship owners will have few choices, dependingon available capitaf and on the condition of their paintsystem. Choices will include:

anti-corrosive and anti-fouling system

anticorrosivg recoat with anti-corrosive and a TBT-free compliant new anti-fouling system

recoat with a compliant non-TBT anti-fouling system.This option may only be taken if the existing system isa suitable candidate for sealing i.e. no excessive heavybuild-up of heavy coatings, no detachment ordelamination of coatings.

Whichever option the ship operators decide, there will be aneed for quick dry-dock turn around on ship repainting.

Effective solutions will be in high demand globally.Shipyards have been planning for such demand for sometime, and ultra-high pressure water-jetting using roboticcrawlers, coupled to closed loop filtration will provide avery effective solution to this global dilemma in the future.

Summary

Abrasive blasting has been present in this country andworldwide for nearly a century. Conventional abrasiveblasting is an effective tool for preparing surfaces forpainting and will continue to be used quite readily forcertain applications. Changing environmental regulationshave welcomed the ever-increasing presence of ultra-highpressure water-jetting as a means of surface preparation ofexisting coatings.

The M2000 technology has several positive intangibles,$ome of which are sometimes difficult to quarfiifyfinancially.l)- Full service hull preparation (sweeping, spotting, andfull coating removal) can be offered with one high speedcost effective system.2)-Coating performances improve from a significantincreases in adhesion levels.3)-Coating blister formation decreases with the reductionof surface contamination.4)- Coating warranties from major paint companies may begiven with confidence that coating performance willachieve the best possible outcome.5)- Source point discharge control of hazardous wastevirtually eliminates workers health and safety issues.6)- Damage to shipboard and yard equipment from spentsandblasting abrasives is eliminated.

With maintenance dollars constantly being diverted, anddemands for quality being enforced, robotic water-jettinghas become the zurface preparation method of choice formany in the marine industry. Worldwide restrictions onthe removal, containmen! and disposal of hazardousantifouling coatings will ensure the continued growth andacceptance of robotic water-jetting with on-site semi andclosed-loop water featment. High speed automated roboticwater-jetting is quickly becoming the efficient win-winpreferred zurface preparation method for shipyards, owners,operdors, and coating manufacturers.

REF.TRENCES

1. P. Parson" W. Kenagy, K. Kettel, "Low Cost AbrasiveBlast Process for Lead Paint Removal",NAVSEA/PSNSY Technical Paper, November 1995

National Shipbuilding Research Program Project 3-96-4, "Productivity Study Hydroblast Removal ofCoatings", Reference 0520, December 1998

G. Kuljian, D. Melhuislq "Evaluating the Productivityof Waterjetting for Marine Applications", Journal ofProtective Cmtings und Linings, August 1999, 3&6

J. Williamg R Ricq *NaW High Pressure WaterjetCloseddoop paint Stripping Syster4 Journal of ShipProduction, February 1996

B. Goldie, "Comparing Robotic Units tdade to CleanVertical surfaces with UHP Waterjetting ProtectiveCoatings Europe, September 1999, 9-18

"Surface Preparation At the cutting Edge",International Ship Repair News, July/August 200 1

B.W.Thomas, "Marine Antifoulants: CurrentRequirements and Experiences in the U.S.Challenges in Negotiating the Global Treaty on TBT",Keynote Address of the lOe International Congress on

Marine Corrosion and Fouling, Melbourne Australia,Feb 1999

Supervisor/Competent Person Training for Deleadingof Industrial Structures, SSPC Course C-3, Version 41997 Student Text

R. Kogler, B. Shaw, D. Melhuish, "Cost EffectiveTechnologies for Bridge Maintenance Painting",Proceedings SSPC99 , Houston TX, 60-66

W. Senich N. Lagendylq " Waterjetting, Innovatior4and a Joint Warranty Made Possible the QuebecBridge Restoration Project", Proceedings SSPC 2000Nashville TN, pages 247-254

R. Dupuy, "Ultra-High Pressure Water jetting forMaintenance Coatings Operations", Journal ofProtective Coatings wdLinings, July 2001 ,68-75

Joint Technical Standard SSPC-SP I2ATACE 5,Surface Preparation and Cleaning of Steel and OtherHard N4aterials by High and Ultrahigh-Pressure WaterJetting Prior to Recoating , 1997_

E. Dunbar, "The Benefits of lJltra High PressureWater-Jetting in Lead Abatement of Storage Tanks",Proceedings SSPC2000, Ivlemphis TN, 233-237

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