Blast room prepares cranes for coating

A purpose built blast room and paint spray facility has been installed at a crane hire company to surface key or anchor pattern for accepting accept a polyurethane coating.

One of the attributes which keeps HTC Plant a leader in the hire of tower cranes is a sustained investment in product quality.

The installation of an Airblast shot blast and paint facility at its Sheffield depot is a case in point.

By the very nature of the tough working conditions and sometimes inclement weather they are asked to operate in, upon return to HTC's Sheffield depot, hired cranes can have areas where paint has been damaged and corrosion started to appear.

"It is important that we maintain a professional image at all times," says Alex Lowe, director and general manager of HTC Plant.

"Our equipment is used on major civil engineering contracts, nationwide and can be seen from miles around, so we always ensure that before going out on hire, every crane is fully inspected and leaves the depot with pristine paint work.

In order to achieve the surface key or anchor pattern necessary to accept HTC's distinctive red polyurethane coating, blast cleaning is essential, so when the company moved to larger premises in Sheffield, one of the earliest decisions taken was to install a purpose built blast room and paint spray facility.

HTC Plant is a member of the P C Harrington Group and as one of its sister companies had been successfully using an Airblast facility for many years, Alex had no hesitation in calling in the Peterborough based specialists.

The Airblast proposal comprised: a 15m long x 5.5m wide x 5.5m high, rubber lined shot blast room complete with end doors, pedestrian doors, modular roof lights, an Airflex abrasive recovery system; bucket elevator/separator; blast cleaning machines and a dust collector.

The blast room was to be linked directly to a similar sized combination paint spray and bake oven.

Airblast's proposal was accepted and the facility installed.

Now, up to three assembled crane sections can be loaded onto an air-driven trolley which carries them on rails into the blast room.

The outer door is closed and blast cleaning commences.

Once prepared the sections are inspected and welds tested to highlight any damage that may have occurred on site.

Assuming no repair work is required they are then moved directly into the paint booth where they are sprayed and baked.

A roller shutter door and ventilated 'air-lock' separates the two rooms to ensure that dust or debris cannot be transferred from one to the other.

Such is the success of Airblast's design and manufacturing precision, if demand dictates it, blasting and painting can be a more or less continuous process; crane sections can be prepared in the blast room whilst spraying or curing is carried out in the adjacent booth.

A key feature of the blast room is the highly efficient Airflex under floor media recovery system which offers many advantages over conventional screw and trough systems, principally high media recovery efficiency, low energy consumption and virtually silent running.

Tried and tested in blast rooms throughout the world, the Airflex system consists of three full length 1200mm wide floor corridors, each covered with heavy duty grating.

Each includes a series of scrapers which continually sweep used abrasive on the forward stroke to a transversal corridor.

In HTC's case, the central corridor is sunk by two metres to allow the operator to clean underneath the crane struts without having to move them.

Used media and debris is transferred via a bucket elevator to a separator which returns good material to the blast cleaning machines and sends dust, debris and broken down particles to a dust collector for disposal.

Excellent air flow through the room provides operators with clear visibility during blast cleaning.

The blast machines are fitted with Thompson metering valves which allow the operator to shut off the blast media after cleaning and 'blow down' with air only.

In this way any lying media is removed and not carried out on the cleaned struts.

The spray booth/oven uses under floor ventilation and filtration during spraying to remove airborne paint particles, then at the touch of a button, dampers redirect the air to circulate within the room for the 'bake' process.

Alex Lowe concludes: "We are delighted with the new installation which fits our requirements precisely".

"The engineers who carried out the installation were without doubt the most professional and safety conscious I have come across and their willingness and versatility in accommodating our changing requirements, some times on a daily basis, was much appreciated.

"I would have no hesitation in recommending Airblast to anyone - without doubt they have the most technically advanced products and are the most professional and dedicated company in their field.

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