in Vol. 13 - November Issue - Year 2012
Vacuum Abrasive Recovery Systems: Impact Blast Cleaning Made Easy
Synco vacuum recovery system
Abrasive Impact blasting is critical for surface preparation prior to coating for corrosion protection, whether it is metalizing or painting. Unless the underlying surface is thoroughly cleaned and certain roughness level achieved, adequate bond strength cannot be achieved, resulting in pre mature peeling off of the overcoat.
With the increase in metal prices, man-hours and energy costs besides a huge cost involved in down time required for repairing and replacement, there is no choice but to opt for the best possible corrosion protection measures for critical and difficult-to-replace objects.
In order to get the best results and reduce the cycle of repainting and not to allow the corrosion to set in underneath the un-damaged paint coats, surface preparation prior to coating becomes critical. The best possible way to achieve this is by way of abrasive impact blasting.
In situ, large objects like tank farms, ships, large vessels, long pipelines all requiring impact blast cleaning from inside cause certain operational difficulties. In the case of ships with difficult-to-reach areas, angles and corners as also for vessels and objects in refineries, chemical plants, power plants, boilers etc., vacuum blasting is difficult to carry out and is sometimes completely impractical due to difficulty in handling the heavy gun with dual hoses and the necessity to keep the brush constantly in touch with the surface to avoid spillage of expensive media. However, alternatively, when direct pressure blasting is used, collection and recycling of media becomes difficult as the media needs to be collected and carried back to the blasting machine which is normally stationed at ship deck level or outside the tank / vessel as the man-holes do not permit the machine¡¦s free movement and its stationing near the blasting point.
In order to overcome this operational difficulty, Synco has developed a portable vacuum abrasive recovery machine with multi heads capable of sucking chilled iron / steel grit having high density and particle size up to 1 mm, also less dense media like garnet / copper slag / aluminum oxide etc. Besides sucking media, the vacuum abrasive recovery machine also sucks in dust and debris and while doing so, helps in ventilating the closed atmosphere of the blasting zone, particularly in ship hulls and tanks and vessels. The portable machine platform is connected to a reclaimer and dust collector wherein oversized debris is separated and undersized media and dust is segregated and cleaned, with usable media being recovered and fed back into a portable blasting machine stationed near the abrasive recovery unit or when it is taken down from the deck or it is lowered in the vessel; the clean and reusable media travels to it through a hose by gravity.
A non-intermittent process of blasting thus becomes an almost continuous system with significant qualitative improvement because of reuse of cleaned and classified media. Also, this system provides the flexibility of using a reusable and recyclable medium like steel grits which is more economical, less dust-generating and more effective in terms of productivity as against expendable / mineral-like abrasive media such as copper slag / garnet / aluminum oxide etc., which have no or low recyclability and generate a lot of dust. There is also the issue of a huge quantity of media handling while garnet and copper slag grits can only be recycled for a maximum 1-2 times; even aluminum oxide grits cannot be recycled more than 10-15 times against which steel grit or high chrome grits can be recycled 100-300 times. Even where 100% recollection is difficult and expendable media has to be used, use of this system brings down the cost of tedious media handling significantly, while accelerating the process of blasting resulting in significant savings in downtime.
The abrasive recovery unit supplied by Synco to a number of shipyards has a capacity of 1500 kgs / hour to 6000 kgs / hour in terms of lifting of chilled iron / cast steel grits up to 1 mm particle size at a depth of 15 meters and a length of 25 meters. These machines have been custom designed. Synco can design and supply such machines with higher capacity in terms of quantity recovered and particle size both at greater depth and distance, as may be required.
Also, Synco is currently in the process of designing such systems for mineral processing industries as well for vacuum collection and pneumatic conveying of minerals needing evacuation like lime and coal from elevator pits or on the sides of conveyors. Also, items like fly ash, cement, mineral powder spillage during grinding processes can also be very efficiently collected and transported at very low operating cost.
Synco can even supply such machines with blasting machines too, built on the same platform with a fully self contained reclaimer / reverse pulsejet cartridge filter, and air compressor, for providing the pulsing air and a control panel. When the machine is wheel-mounted, an arrangement is also made to station the equipment on jacks while under use. Similar stationery equipment is supplied for collection of abrasive media from large blast rooms where heavy objects are blasted having irregular and ever changing profile making it difficult to have perforated flooring with hoppers in the pit and mechanical collection of media. In such cases, manual media collection and recycling becomes a pain in the neck! Synco¡¦s abrasive recovery units are ideal for easy media recollection, cleaning and recycling, enhancing the productivity of any integrated blast room system.
Synco also makes blasting-cleaning solutions easier by providing customized object handling with gun manipulation and media handling systems using air-assisted, airless and hybrid processes. Different types of conveyors, single and multi-satellite turn tables, X-Y manipulation, robotic arms for gun manipulation, nozzle reciprocation etc., are routinely designed and supplied with PLC-based controls and man-machine interface.
Synco¡¦s strength lies in providing concept to commissioning of customized solutions relating to abrasive impact blasting, painting, metalizing, ventilating, climate control for dehumidification dust and fume evacuation, air heating and air cooling, pneumatic conveying, object handling, gun manipulation and on site / off site coating services: i.e. flame / arc / plasma / HVOF spray systems. Over the last 15 years it has emerged as a one-stop solution for meeting all the needs of equipment design, manufacturing, supplying, commissioning, training and supplying of all kinds of standard and customized spares, consumables, abrasive media, wires and safety wear, etc.