Successful maiden voyage for recycled glass at hull shipyard

Citation

(2006), "Successful maiden voyage for recycled glass at hull shipyard", Pigment & Resin Technology, Vol. 35 No. 6. https://doi.org/10.1108/prt.2006.12935fad.003

Successful maiden voyage for recycled glass at hull shipyard

Successful maiden voyage for recycled glass at hull shipyard

Keywords: Recycling, Glass, Transport engineering

It is full steam ahead for a new grit blast medium made from 100 percent recycled glass after groundbreaking trials confirmed its advantages as a method of cleaning steel and preparing metal ready for painting.

The results of the full scale test at Dunstons Ship Repairs in Hull, announced this week, are part of a wider series of trials commissioned and funded by WRAP (the Waste & Resources Action Programme) and managed by the Shipbuilders & Shiprepairers Association (SSA).

Carried out in controlled conditions, the trial compared the performance of recycled glass grit with copper slag – the shipyard's usual abrasive – in blasting a mooring pontoon.

Preparing surfaces by grit blasting – powering abrasive particles onto them, using high pressure air – is the preferred method in the marine industry as it is often the fastest and most thorough means of removing iron oxides, rust, oil, grease, dirt, old paint and other surface contaminants from vessels prior to making repairs and alterations.

Cleaning also tackles corrosion caused by soluble salts in the air and water – a major problem, which can lead to premature paint failure if not removed.

Graham Billany, Managing Director at Dunstons, said: “We've used copper slag for more than 30 years and while this is a cost effective material we were interested in exploring the potential of recycled glass grit as an environmentally friendly alternative.”

“We agreed to a full scale trial, after the results of preliminary tests on different steel samples, including man hole covers, rusted cargo hold plates and heavily pitted ballast tanks, proved very encouraging.”

In the initial trials, recycled glass demonstrated improvements in productivity over the traditional copper slag of up to 240 percent and the time taken for blasting was reduced by up to half.

The performance of medium grade recycled glass grit supplied by Wolverhampton Abrasives was compared with copper slag using the same blasting equipment.

Split into two sections, the deck of the pontoon had numerous layers of paint from overspray during repairs, while the sides and bottom had one coating and areas of rust.

On the deck, the recycled glass was 16 percent quicker and on the sides and bottom it performed similarly to copper slag, giving a brighter finish which appeared to be cleaner.

Mr Billany said: “We've been pleasantly surprised by the results of these trials which have clearly demonstrated the time, productivity and cosmetic benefits of switching, and we are now looking into the wider implications of using recycled glass grit.”

In addition to representing a more sustainable use of resources, recycled glass grit's main benefits over conventional blast media are that it is non-toxic, inert and does not cause respiratory or environmental problems. Unlike some traditional media, it does not contain crystalline silica or heavy metals and so can be used in public places and environmentally sensitive areas, such as watercourses.

Glass grit is also free of chlorides and salts that can corrode clean surfaces so its use delays “gingering” of steel, and – through spent media being classified as a nuisance dust, rather than hazardous waste – can offer lower disposal costs.

In contrast to most conventional abrasives, recycled glass does not have to be imported, meaning shorter delivery times for blasting companies and potential environmental benefits, through less energy being used in transportation.

Tom Dougherty, Director of SSA, said: “These trials are part of a wider programme, running since April 2005, designed to establish whether recycled glass grit can achieve a comparable surface profile to conventional abrasives, such as metal slags, olivine and garnet.”

“Carried out at a number of yards around the country, we've been encouraged by the results produced so far, which demonstrate it represents an easy to use, commercially viable alternative, taking into account its cost and the surface area that each tonne of material can treat.”

Dunstons' 70-strong team on the River Humber completes more than 300 ship repairs each year, with 50 in dry dock. In addition to maintenance, it offers lengthening, refurbishment and conversion work, and services a wide variety of vessels including fishing trawlers, cargo ships, tankers, gas carriers, dredgers, barges, tugs and ferries.

Andy Dawe, Materials Section Manager (Glass) at WRAP, said: “We've been aware of the advantages of recycled glass grit in the UK for some time, but our task has been to demonstrate the operational and commercial benefits to the market by funding trials such as these.”

“In the USA, glass grit has been proved to effectively clean masonry, renovate equipment and restore woodwork, among other applications.”

“We're delighted the marine industry is recognising the potential of this new medium and hope specifiers and contractors will now use it more widely.”

“The results of these trials will have implications for a wide range of industry sectors which use grit blasting extensively to clean, descale, deburr and remove surface contaminants.”

The widespread use of recycled glass will assist the UK in meeting its target under the European Union packaging directive, which says 60 percent of glass must be recycled by 2008. Preliminary data for 2005 indicates that 50 percent was achieved.

Recycled glass is available manufactured to BSI PAS 102 specifications, setting standards in terms of colour, contamination limits, particle size requirements and appropriate test methods, guaranteeing a consistent, high quality product.

Any companies interested in setting up a trial or learning more about recycled glass applications should contact Andy Dawe at WRAP on 0808 100 2040.