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FAQ
- Can you repair holes in my water tank or cooling tower?
- Our cooling tower is leaking from the joints and the internal coating is de-bonding...
- Our GRP Tank is leaking. The manufacturers guarantee is now invalid. Can you repair and reline our tank?
- We need an urgent budget price. How can I get one?
- Can your applied product help prevent the risk of Legionella in my water system?
- Our water tank is in a plant room where the roof of the plant room is extremely close to the roof access of the tank...
- What is the difference between 3M™ Scotchkote™ Urethane Coating 165PW and an Epoxy coating?
- How is your product different to a Butyl or PVC Liner?
- Is Bitumen a suitable coating for potable water tanks?
- Our steel tank is corroded. Should I not just install a replacement?
- Can 3M™ Scotchkote™ Urethane Coating 165PW be applied to any substrate?
- Is fibreglass a good option for the relining of our water storage tank?
Can you repair holes in my water tank or cooling tower?
Yes! We have successfully repaired and relined many water tanks and cooling towers that have developed holes due to excessive corrosion.
View some PDF completion reports here and here.
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 PDF completion report here.
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.
We need an urgent budget price. How can I get one?
All you need to do is fill out this enquiry form - click here.
Can your applied product help prevent the risk of Legionella in my water system?
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.
What is the difference between 3M™ Scotchkote™ Urethane Coating 165PW and an Epoxy coating?
3M™ Scotchkote™ Urethane Coating 165PW 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.
3M™ Scotchkote™ Urethane Coating 165PW 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.
How is your product different to a Butyl or PVC Liner?
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 some PDF completion reports on Butyl and PVC Liner problems over here.
Our potable water storage tank is coated internally with bitumen. Is this OK?
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.
Our steel tank is corroded. Should I not just install a replacement water storage tank?
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 this page.
Can 3M™ Scotchkote™ Urethane Coating 165PW be applied to any substrate?
3M™ Scotchkote™ Urethane Coating 165PW 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 PDF 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:
- Cause acute irritation to the eyes, nose, throat and skin.
- Gastrointestinal symptoms such as abdominal pain and diarrhoea, often referred to as the "Styrene Sickness".
- At high levels, chronic bronchitis type symptoms and other respiratory symptoms can appear. Multiple central and peripheral acute nervous system effects have also been described, but some neurological symptoms and colour vision impairment may also appear at much lower levels.
- In the past, the so called “Styrene Sickness” has been described by workers exposed to styrene as : nausea and vomiting, loss of appetite and general weakness.
Osmotic Blistering
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.
Water Ingress
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.