Yes! We have successfully repaired and relined many water tanks and cooling towers that have developed holes due to excessive corrosion.
The mastic between the steel joints of the tower can deteriorate very rapidly in a cooling tower due to the aggressive nature of the dosed water. Once the mastic starts to degenerate it loses its elasticity and consequently, fails to meet the demands of the structural movement within the tower.
Various coatings are applied to the internal surfaces of cooling towers, from Bitumen and epoxy coatings to Polymeric Hybrid thermosetting Powder, which is fuse bonded to the substrate (eg. Baltibond). In our experience, these types of generic coating systems fail due to poor elongation properties and low chemical resistance.
View a relevant completion report onCooling Towers.
Yes, there are numerous problems that can occur with Glass Reinforced Plastic Water Tanks (GRP):- Mould growth, cracks and air filled cavities that provide a home for bacteria and corroding fasteners but the most common problem is leaking from the joints. COVAC have a solution to all these problems. Visit this link for more information.
All you need to do is fill out this enquiry form - click here.
Yes! Check out this link for further information.
We have a vast experience in working on water retaining structures that have difficult access and egress issues. One of the most common problems is when the roof access of the structure is extremely close to the roof of the plant room itself. There are various ways of solving this particular problem.
View a relevant case study here, showing an example of us solving the access issue at a large hospital.
Acothane DW is a solvent free polyurethane which is WRAS/DWI approved for water retaining structures, manufactured from concrete, steel or GRP (Glass Reinforced Plastic). Most Epoxy coatings that have DWI Approval are only approved for steel.
Acothane DW has approximately 35% elongation properties, which means it has the capabilities of accommodating the anticipated structural movement which you would expect in all types of water retaining structures. Epoxy coatings are generally quite 'brittle' coatings and will crack and subsequently, de-bond under the slightest stress or movement within the structure.
View a relevant case study here.
Butyl bags tend to be used for a 'quick fix'. They are, essentially flexible liners that are suspended from the top of the tank (usually by aluminium strips). They do not address the problem of corrosion in the structure especially the roof, which usually remains completely unprotected, allowing the risk of contamination from bacteria (including Legionella) when condensation forms and drips back into the potable water. COVAC are usually called in to urgently rectify jobs where these liners have been installed because they are generally quite flimsy and once even the slightest damage occurs, the water in the structure traverses through the damaged area (even a small 'pinhole') causing ingress of water between the substrate and the liner.
This usually results in water stagnating behind the liner causing a risk of bacterial growth and eventually, pushing the liner to the top of the tank and causing the tank to overflow.
View a completion report on Butyl and PVC Liner problems over here.
Bitumen has been prohibited for use by the WRAS for many years now. Most bitumen based products will not resist the growth of micro-aquatic organisms, therefore your tank is at risk of sustaining bacterial growth if the bitumen remains. We would always recommend the full removal of bitumen from a potable water tank or cooling tower.
Check out a completion report on the removal of bitumen here.
Many engineers believe this choice to be the 'Rolls Royce' option (usually because it is the most expensive option). By the very nature of the fact that 25% of our current turnover is catered for by the repair and relining of Glass Reinforced Plastic (GRP) water storage tanks, we would have to disagree.
From experience, we have found that most engineers exchange the problem of corrosion (of their existing steel water storage tank) for the equally, (if not worse) problems of erosion, corrosion of steel fasteners, deterioration of the mastic between the joints (and consequential leaking) and mould growth.
Find out more on here.
Acothane DW is WRAS / DWI Approved for concrete, steel and Glass Reinforced Plastic (GRP) and has excellent adhesion properties for all these (and other) substrates.
Fibreglass Systems would never qualify for drinking water under DWI (Drinking Water Inspectorate) due to the various levels of styrene within fibreglass lining systems.
View a completion report demonstrating some of the regular problems.
There have been many documented cases of water contamination from styrene following refurbishment of water tanks utilising fibreglass lining systems. This usually starts with a 'strong solvent-type smell' in the water, followed by a thin gelatinous layer that can usually be seen 'floating' on top of the water in the tank. When the tank is used for activities such as drinking tap water, eating foods prepared with tap water, bathing, showering, etc, then the styrene content in the water (apart from tasting badly) can potentially:
The problem faced by all engineers who are responsible for the maintenance of potable water tanks is that even with regular cleaning and chlorination, bacteria such as micro-aquatic organisms will continue to multiply as they are protected in the habitat provided by air filled cavities and fine cracks in the fibreglass that often cannot be seen with the naked eye. These cavities and cracks allow bacteria to nest and proliferate.
The problems start to occur when the water molecules migrating into the fibreglass encounter other chemicals inside the laminate, primarily water-soluble materials (WSMs) such as the emulsion binders or resin used to hold the glass mat together, or pockets of uncured or only partly cured resins. The water molecules can then have a chemical reaction with these substances, forming larger molecules of a new chemical, often acidic – which unlike the original small water molecules, cannot carry on passing through the fibreglass. These larger molecules are then trapped. This is the point at which osmosis actually starts.
Osmotic blistering of the fibreglass substrate due to water permeation can also lead to deterioration of the gel coat and, subsequently, a surface which is highly likely to harbour and promote the growth of micro-aquatic organisms.
It should be bore in mind that, if ignored, such internal water osmotic blisters will eventually burst putting their contents into the potable water. These chemicals not only have a very unpleasant taste but are also toxic! For this reason, fibreglass is not recommended or approved by the DWI for drinking water tanks.
Find out more here.
Another common fault associated with fibreglass coatings is failure due to water entrapment.
Fibreglass Systems are often used in combination with slow curing epoxy resins and gel coats, which are extremely slow curing and are subsequently susceptible to 'holidaying' or 'pin-holing'. There is also very little adherence between the substrate of the water storage tank and the fibreglass lining. The water then traverses through these holes and travels between the tank substrate and the fibreglass lining. This continues until the fibreglass lining becomes detached from the substrate and partial, if not complete, failure occurs.