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Projects - Case Studies

PAST & CURRENT PROJECTS - MINING | ENGINEERING | HEAVY PLANT | POWER PLANT NAVAL

Bucket Conveyor Rebuild

Mectek were called to Castle Cement at Ketton in Lincolnshire when a 1000 tonne per hour bucket conveyor snapped during process.  The conveyor snapped full of material and fell 60 meters down from the top of the silo.  The conveyor chain ended up in a dangerous position overhanging an access walkway.

The chain weighed approximately 150 tonnes.  The first task for mectek to undertake, was to make the area safe to work.  The chain had coiled up overhanging the access walkway, so wire rope winches were attached, to pull the chain back to the top, and chain blocks attached above the chain to prevent it falling down further.

The following year we were asked back to refurbish the adjacent machine in the annual shutdown.  We spent three weeks replacing 200 meters of chain in 3 meters sections.  We used our lorry mounted crane to lift the sections through the roof and into position.

The chain took seven days to pull back into position and a further two weeks to repair all the damaged chain links.  Six 5 tonne pull winches were used to pull the chain up and ten 5 tonne chain blocks were used to support the weight of the chain over the length of the conveyor.

Contract value £130,000.00

Refurbishment of Clova Vessel Ring Beams

Mectek was employed by Bairds Malt to refurbish their clova vessel revolving floor.  The Clova vessel is a 500 tonne capacity combined Germination and Kiln vessel, which produces malt for the distillery market in Scotland.  The vessel is approximately 30 meters in diameter, it has a mesh deck level which is supported by 36 radial beams, the radial beam sit on ring beams, one in the centre, which supports and centres the floor, and an outer ring beam which incorporates a drive rack, which is driven by four large motors and gearboxes.  Within the vessel there is a turner and loader unit, the grain is conveyed into the vessel, and the loader unit discharges the grain on the deck floor.  The floor then rotates unit the vessel is full.  It takes approximately 2 and a half hours to for the floor to rotate one revolution.  The ring beam sits on 84 stainless steel floor rollers, the rollers take the full load of the vessel and allow it to rotate.

Our task was to fully overhaul the ring beams and drive system on the vessel.  To undertake this work we had to lift the deck floor and support it while we replaced the drive racks and wear strips on the ring beam.  The floor weighed 120 tonnes, and to lift this we used hydraulic jacks.

Part of the refurbishment, was to replace the floor rollers, which were damaged beyond repair.  Accessing the floor rollers during production was not possible, so maintenance work was limited, when floor rollers failed they damaged the ring beams, so we were asked to come up with a solution which would allow the vessel to run for longer periods of time between maintenance breaks.  Our solution was to design a nylon pad to replace the roller, the pad would have to withstand the the massive weights of the floor and have a low coefficient of friction, so the floor would slide freely.

The nylon pads were cheaper than the floor rollers, they would wear evenly and would not damage the ring beams.  The brief was to refurbish the floor, giving a working life of five years until the next major overhaul.  Six years on and the floor is still working, and there is no damage to the ring beams, the nylon pads have been changed a few times, but this is a relatively simple maintenance task.  The whole refurbishment job was completed in 6 weeks.

A view of the inner ring sitting on nylon pads complete with an automatic greasing system.

The refurbished ring beam sitting on a nylon wear pad.

The fitting of one of the four floor drive gearboxes, which was refurbished in our workshop.

Coors Shobnall Maltings - Design and build Kiln Slew Ring

Mectek were employed to design and build a new inner slew ring for there tower kiln.  The existing slew ring had become worn and caused excess friction, this resulted in multiple failures to the drive system.  The ring was not repairable, so we designed a new support system which would allow ease of maintenance and replaceable parts.

The structure was fabricated and assembled in our workshop, it comprised of 20 fabricated petals which bolted together and in turn bolted to the concrete core. On the petals sat 20 support rollers and 10 guide rollers. The rollers were machined from stainless steel and sat in a galvanised steel carriage. On top of the rollers sat a ring beam, fabricated from a structural hollow section, which was fabricated in four sections and bolted together. A replaceable wear strip was then bolted to the ring beam.

The next task for the project was to design a safe system and program of work. The installation would require minimum down time and a precise method of supporting the 100 tonne floor while the support ring was replaced. To do this we designed and build another support ring which would bolt to the beams of the floor and 6 jacking stools. Using a synchronised jacking system we were able to lift the floor and support the weight while the supporting structure was replaced.

The jacking system allowed for the floor to be lifted accurately and level, and be able to be continually monitored while the work was carried out.

The hole structure weighed approximately 10 tonnes, and when in operation had to support 160 tonnes and revolve without excess friction.

The old support structure was then removed, and the ring beam assembled around the core. New beam supports were bolted into place and the ring beam lifted up using chain hoists.

Each stage of the installation required purpose build lifting attachments to position the sections safely into place.

When all the component parts had been fitted the jacks were lowered and the floor sat on the rollers.

The project was completed in 16 days.

Coors Brewers Shobnall Maltings - Refurb of Vessel Inner Ring Beams.

Mectek was employed by Coors Brewers to refurbish their Germination Vessel revolving floor inner ring beams. There were four vessels to refurbish, one a year.  The vessels are 20 meters in diameter and weigh 400 tonnes when full.

The task was to suspend the floor from the central column by using chain blocks bolted to the wall.  The inner ring beams were approximately 6 meters in diameter.

The ring beam sections were taken to our workshop, where the damaged bottom wear strip sections were cut off and replaced with bolt on wear strips made from stainless steel.  This involved bolting the ring beam together in the workshop, machining the sections flat, and welding sleeves through the ring beam, so bolt on stainless sections could be fitted.

This is a view from under the floor. Showing the supporting stools which the rollers sit on.  The rollers were replaced with nylon pads as the refurbishment in Arbroath.

The work was completed within the time scale set out by Coors.

Contract value £70’000.00 per vessel

After fabrication the sections were shot blasted and painted and delivered to site for installation.

Mectek undertook the design changes to the ring beams, the fabrication work and the machining of the nylon wear pads, the design of a safe system of work for lifting the vessel floor and the installation.