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FOCUSONcoating applicatorsFOCUSONCONSULTANTSCorrosionManagement | March/April 2012RHINOCEROSQueen Elizabeth II BridgeOne of Belfast’s road bridges is about to emergefrom major refurbishment, a challengingjob completed against tight deadlines. Thecoating contractors are RHINOCEROS, aquickly growing infrastructure maintenancecompany based in London.2012 is a special year for Belfast: not only is itthe Titanic Centenary year, but also the Queen’sDiamond Jubilee. A landmark common toboth is the Queen Elizabeth II Bridge. Thebridge was opened by the Queen in 1967, andspans the River Lagan just a seagull’s hop fromthe Harland and Wolff yard which launchedthe most famous ship in history. The massiveshipyard gantries are now sadly quiet, but theQueen Elizabeth II Bridge is busier than ever.The Department for Regional DevelopmentNorthern Ireland decided late last year to giveit a proper refurbishment as part of the BelfastCity’s preparations for 2012.The contract was always going to presentspecial problems, and RHINOCEROS sentan experienced Contract Manager, BillPrendergast, to inspect the Bridge and preparetheir plan. Time was already tight – thedeadline was April 2012 and the contract wasonly awarded in December 2011. Inspectionsrevealed extensive corrosion and failure ofexisting coatings, most visibly on the parapetsand handrails. The beams underneath wereworse: pigeons had deposited up to 7” ofguano throughout the structure, and theexisting chlorinated rubber coatings wereseverely damaged.Refurbishing any transport infrastructure canbe a logistical headache. The Bridge had to bekept open to road and foot traffic throughoutthe operation, and there were plenty of minorinconveniences, such as a one-way systemwhich meant a City centre detour to movesupplies and plant from one end of the Bridgeto the other. On top of that, work was to startin February, when cold and damp could beexpected to be at their worst.RHINOCEROS built its early reputation ongraffiti removal and anti-graffiti coatings,but are now just as likely to be seen tacklinglarge infrastructure maintenance projectsall over the country, and beyond. Lateralthinking and problem-solving approach haswon the RHINOCEROS team friends in manymaintenance departments. Bill cut his teeth inthe Southampton marine industry and worksboth as a Contracts Manager and as a PaintInspector with ICORR Level 3 accreditation.His team are all ICATS accredited, or workinghard to complete their ICATS training underBill’s active supervision.Concrete refurbishment was being doneconcurrently by Graham Structural Solutionsof Belfast, and they planned to control thetemperature and humidity at levels whichwould allow painting by installing a WackerNeuson ground heater. This powerful US builtheater is designed for thawing out frozenground and heating very large buildings.Calculations showed the device could heatthe entire structure by 1 degree C in 24hours, so less than a week would be neededto take it from 0 degrees C to a workable 5degrees Celsius. In fact, Bill says the heatingwas so efficient that his workmen were ableto do most of their work at a comfortable 15degrees C.The bridge had previously been paintedwith up to 6 coats of chlorinated rubber.Consultations between RHINOCEROS,Belfast’s Road Agency and Mike Taylor of PPG/Sigma resulted in a specification for 40% blastcleaning to SA 2.5, with the remainder of thestructure being sweep blasted to remove onlythe top chlorinated rubber.Mike Taylor says “From experience withHighways Agency bridges, over-coatingthese types of systems can be fraught withdifficulty. Applying an epoxy system such asHA115, HA116, HA168, over the physicaldrying chlorinated rubber systems has led toexperiences of cracking, delamination andcrazing.Success is measured on the long term adhesionof the coatings to all the different surfaces ofthe structure. External areas on outer beamsthat are subject to sun and temperaturerises and falls are far more difficult to coatsuccessfully because of the difference inthermal characteristics of the chlorinatedrubber compared with the epoxy. Thechlorinated rubber will expand and contractwith temperature whereas the epoxy is morerigid and if applied over the chlorinated rubberis likely to crack.Experience from other Highways Agencybridges has shown that on outer beamsthe best option is to remove the existingchlorinated rubber system by abrasive blastcleaning and apply a new epoxy system.The under deck areas, where the existingchlorinated rubber system is more shelteredfrom the temperature fluctuations, canpossibly be treated with an epoxy system. Ithas been found that spot priming with HAItem 115 and then applying HA Item 112 andHA Item 168 can be successful. HA Item 112is preferred because from experience it is moreflexible than HA Item 116 and therefore lessprone to cracking because of the micaceousiron oxide pigmentation. It has also been foundthat the chlorinated rubber systems can havea powdery surface and this is best removed byslight sweep blasting before over coating withthe epoxy system.”The choice of abrasive was also critical.Gerry Bourke of Scangrit said Olivine wasthe preferred option when blasting aboverivers: “Olivine AFS30 and Olivine AFS 20will achieve “Medium” blast profiles on mildsteel as defined by BS EN ISO 8503-1:1995.A medium blast profile is defined as beingbetween 50 and 70 microns and up to 85micron.“In an independent Testing of ExpendableAbrasives conducted by PERA on behalf ofScangrit, Olivine AFS30 achieved a blast profileof 52.9µm and Olivine AFS20 achieved a blastprofile of 68.5µm. The tests were conductedwith a compressor rated at 350cfm at 100psidelivery pressure. The blast nozzle was aventuri type having a nozzle bore of 3/8”.Pressure measured in the grit delivery hose,behind the blast nozzle, was 60psi.”For more information please contact: RHINOCEROS Limited, Huntingdon Works, Huntingdon Road, East Finchley, London, N2 9DXTelephone: 0208 444 6165 Fax: 0208 365 2865 Email: contracts@rhino247.co.uk Web: www.rhino247.co.uk10 14
FOCUSONcoating applicatorsFocusonconsultantsRHINOCEROS Manager Duncan J MacLeansays Olivine also has the advantage of being anatural mineral - in the event of a spill or a tearin the containment sheeting no environmentalcontamination would be caused. “In practicethis has proved to be a smart move. Themen like it and say they never want to goback to using copper slag. It has proved tobe highly efficient in removing the 6 coatsof chlorinated rubber. The AFS30 or mediumgrit has proved to be ideal for sweep blastingthe chlorinated rubber. The AFS20, a coarsergrade, has produced a profile which exceedsthat required by the paint and has satisfiedthe client that his paint is going to stick to thebridge for a very long time!”After heating the area, it took over 100 tons ofOlivine for blast cleaning, the waste having tobe vacuum cleaned off the Terram protectivesheeting and hauled up to the road surface inlarge buckets.The first coating of Sigma 690 was applied byairless spray to a depth of 150 microns. Astripe coat over joints and rivets followed,using Sigma Micaceous Iron Oxide (MIO) to75 microns. This was covered with a furtherfull sprayed coat of MIO to 150 microns, andfinally a top coat of Sigma 550 to 50 microns,in Belfast signature colour Neptune.The parapets and handrails were taken to baremetal SA 2.5, then coated with Sigma 690,a stripe coat of Sigma 456, a further spraycoating of Sigma 456 and a top coating ofSigma 550 in Blueberry and Turquoise.The Titanic continues to generate controversy;latest theories suggest its hull failure mighthave been quickened due to excessive sulphurcontent in the steel. But above water levelBelfast is about to unveil a very attractiveexample of the best modern refurbishmenttechniques.Hankinson Painting GroupHankinson Restore Ancient StructureThe Blasting Division of Hankinson PaintingGroup were recently involved in therestoration of the main span of Powick NewBridge, a Grade II listed structure which carriesthe A449 over the River Teme, approximately2 miles South West of the City of Worcester.The bridge was built in 1837 and consists oftwo side spans and one main span – the mainspan taking the road across the river.The main span (approximately 21 metres inlength) consists of 7 No cast iron arch ribsand deck plates supported on sandstoneabutments. Access to the structure was carriedout using a fully encapsulated hung scaffold.Due to the environmentally sensitive location(river and flood plain) of the bridge no scaffoldcould be erected from ground level.Treatment of the structure consisted of fullfresh water wash down followed by abrasiveblasting of the cast iron using Garnet media(approximately 16 tonne). This was thenfollowed by applying a 5-coat epoxy paintsystem (approximately 950 litres in totalprovidedby Hempel Paints) and a compatiblemetal filler (approx. 60 litres) to all blowholes (honeycomb-which is common in castiron steelwork). All joints/interfaces weretreated using a compatible polysulphidesealant. External side elevations of the MainSpan were then picked out in various colours,which were chosen by the client.Once all works were completed the scaffoldwas dismantled and all contact points wereprepared and treated by specialist rope accessoperatives.Although not a requirement of the contract,all procedures were carried out in accordancewith the National Highways Sector Schemefor Corrosion Protection of Ferrous Materialsby Industrial Coatings (NHSS19A) and alloperatives were ICATS accredited.Operations Manager, Frank Kershawcommented “ The works to the Grade II listedstructure required not only the ability toperform technically challenging operationsbut also for our operatives to incorporatetheir artistic skills to complete the works tothe crest heraldry. I would like to take thisopportunity to commend the labour forcewho worked on the scheme”.All waste generated from the works wascollected and securely stored prior to removalto a suitably licenced waste transfer facility inaccordance with the Company’s ISO14001procedures.The contract has recently been shortlistedin the Industrial Category of the Painting &Decorating Association Premier Trophy Awards.Main Supplier Details:-Item: Protective CoatingsSupplier: Hempel PaintsMaterials:Item 115 - Hempadur Mastic 8588E - 19910Item 116 (Stripe) - Hempadur Mastic 8588EItem 116 - Hempadur Mastic 8588E - 17050Item 116 (Stripe) - Hempadur Mastic 8588EItem 169 - Hempathane Topcoat 5521E – 12-B-21Special/Other Products Used:-Item: Metal FillerSupplier: Hempel PaintsMaterial: Hempel ProFiller 35370Item: Polysuphide SealantSupplier: Adshead RatcliffeMaterial: Arbokol 1000For more information please contact: Central House, Lyng Lane, West Bromwich, West Midlands B70 7RW Telephone: 0870 789 2020email: sales@hankinson.co.uk website: www.hankinson.co.uk11 15
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