This is a transcript of the Belzona “Solve It Session” webinar – Polymeric Solutions for the Water and Wastewater Industries. You can watch the webinar recording below:
Full webinar recording
The Water and Wastewater industries are expansive, with hundreds of areas which can experience damage. This blog will be focusing on three in particular – pumps, pipework and tanks. As these are some of the most common places within the industry where polymeric materials can be used to repair, protect and improve assets.
Firstly, we’ll be looking at pumps within the industry. These can suffer from many damage mechanisms, with the primary being:
- Deterioration due to corrosion
- Deterioration due to erosion
- Impact, chemical attack, etc
Erosion and Wear
Pumps and pipework are under the constant threat of erosion and wear as they handle large quantities of liquid throughout their working day. Entrained solids can damage pump elements and casings can be eroded by constant water flow and corroded by chemicals, sewage and other materials involved in the treatment process.
Long lead times from manufacturers often means that an out of service pump can cause lengthy delays and shutdowns and outright replacement is often prohibitively expensive.
When on site, we need to look for evidence which suggests the cause of damage, so that we can identify the root of the problem. Starting with the above photo, we can see damage from entrainment, or solids suspended within the flow. If this is compounded with corrosion caused by aggressive substances within the flow or sewage, then we can see erosion-corrosion. This is where corroded steel is eroded away, thereby exposing fresh steel which then corrodes and the process repeats, resulting in severe metal loss.
Taking this sewage pump here, we can see that it is heavily corroded. Most asset owners would probably discard this pump and replace it with new. However it is possible to restore these pumps to bring the efficiency back up for the long term using epoxy solutions.
To repair this pump, the first step would be to grit blast the pump. Effectively serving two purposes:
- Firstly it removes all the loose, friable rust and metal, cleaning the surface. Secondly it provides a profile or key for the epoxy to adhere to.
- Next we use a paste-grade epoxy to rebuild the profile of the pump internals and components.
Finally we apply a protective ceramic coating to provide long-term protection against erosion and corrosion.
Another form of damage we may see is cavitation, the evidence of which you can see above. The typical sign of cavitation is localised micropitting, caused by the collapsing of steam bubbles near the surface. This most often occurs in areas of low water pressure, particularly trailing edges of impellers where the pressure is low enough to allow water to boil.
Given the impact nature of cavitation, this calls for a solution with high toughness, as a hard ceramic solution would be too brittle and lack the toughness to withstand the energy of impacts. Therefore, Belzona has developed an elastomeric system to protect equipment against cavitation. This polyurethane can withstand the deformation caused by cavitation microjetting.
Pump Case Study
This application took place in Montreal, Canada, where this pump had experienced severe erosion/corrosion. It had been in operation for several years and was seriously deteriorated. Therefore, the team at the plant thought it was scrap, and wanted to replace it. However, when they visited the pump shop, they were told about Belzona solutions and how polymeric materials could be used to restore their pump.
After consultation, the chosen materials were Belzona 1111 to rebuild the pump and Belzona 5812DW to coat it. Beyond the properties of the materials, which fully restored the pumps as you can see, there were many reasons why the pump shop recommended Belzona. For one, the Belzona brand. We’ve been around since 1952 and in that time have built up a reputation for quality. As well as this, the solutions had NSF 61 approval which was necessary for the plant
How to Protect a Pump with Belzona 5821
We’re now moving on to pipework solutions. Pipes suffer from damage both on the external and internal diameters from both erosion and corrosion.
- Externally we may see environmental attack, which calls for a solution where a barrier is formed between the pipe and the environment.
- Internally we may see damage from erosion and chemical attack, possibly at high temperatures.
These forms of attack both lead to loss of wall thickness, which may eventually lead to live leak situations, often causing the asset to be taken offline whilst it is repaired or replaced . This downtime can be very costly, but by using an epoxy solution these costs can be avoided.
Pipework Case Study
This case study was at a pumping station at Tarragona in Spain, where these water pipes were suffering from significant external corrosion. This was due to leaks occurring through the sealing systems between the pipes, and walls of the tanks.
To create a long-term repair for these issues, Belzona SuperWrap II was chosen to wrap the pipes. Then, on top, Belzona 5811 (Immersion Grade) was applied to provide a smoother finish to the repair. As well as this, the concrete tank was repaired with the mortar repair material Belzona 4131 (Magma-Screed). To complete the application, the pipes were coated in a blue polyurethane material, as this was the specification of the station.
There were several reasons Belzona materials were chosen for this application. Belzona SuperWrap II is a ISO/ASME compliant wrap solution. It also has outstanding properties and will restore the mechanical strength back to the pipes for twenty years. The application was able to take place whilst the pipe was online, without any disruption to the water supply. Consequently, more than 30 other smaller compliant repairs were carried out around the same facility with Belzona SuperWrap II.
WRAP AND PATCH REPAIRS
Belzona can use epoxy solutions to reinstate pipe integrity and reinforce the asset, using patch repairs or full circumferential wraps.
In order to protect against this happening in the future, we can carry out an internal coating of the pipe to protect against erosion and corrosion. Depending on access, this can be done by hand or for smaller diameters, by spin spray methods. Belzona coatings can provide protection against erosion, corrosion and chemical attack, even at elevated temperatures.
Next we’re going to be looking at Tanks and Clarifiers within the industry. We’ve split this into three areas which typically experience damage – tank exteriors, tank interiors and concrete.
Sealant failure, adverse weather conditions or condensation can lead to corrosion of the tank base, tank failure and ultimately – leakage. Tank roofs are susceptible to rapid deterioration caused by the corrosive vapour of the stored media. Tank walls can also suffer from corrosion and leaking welds.
To combat tank base problems, Belzona formulated a tank base sealing system in the 1990s, which is liquid applied in conjunction with a reinforcement sheet. As a flexible membrane, the system possesses a unique breathable feature; liquid cannot permeate the membrane. However, the vapour escapes freely, allowing the underside of the tank to dry out.
Roof and wall damage can be safely repaired in-situ and on-line, eliminating the need to drain the tank.
Tank Case Study
This case study took place at a water treatment plant in the south of England. The tank was suffering from corrosion issues around the seam areas. And in two places the corrosion had resulted in holes in the tank, meaning the raw sewage was leaking out.
Whilst deciding what to do with the tank – whether to repair or replace it – the treatment plant asked Belzona to provide a solution, to keep the tank usable for the time being.
Therefore, temporary patches were installed using a Belzona system. Fast-curing materials were necessary because as all work had to be carried out in just one day, as the tank had to be put back into service at the end of the shift.
Consequently, a surface-tolerant material was used to patch over the holes before Belzona 1161 was used to bond the patches. After the application, the customer was very happy with the repairs and instead of building a new tank, chose to line the inside with a Belzona System.
Steel vessels, ranging from drum thickeners to digester tanks, are subjected to a range of harsh conditions by the water and wastewater industry.
MIC (Microbially Induced Corrosion) can occur to the substrate. Whilst the chlorides and sulphates present in wastewater sludge can similarly corrode steel vessel interiors, and these are just examples of the many forms of attack. Concrete tank interiors can be eroded by submersion in water or corroded by chloride chemical attack, leading to cracks and leaks, resulting in compromised water quality and plant efficiency.
Belzona coating solutions are designed to protect tank and vessel interiors by providing a chemical resistant internal lining. Belzona 4311 (Magma CR1) is designed to protect secondary containment areas against chemical attack, whilst Belzona 5811 (Immersion Grade) can protect surfaces subjected to constant or regular immersion in aggressive liquid environments. For the water and wastewater industry, Belzona 5812DW is approved for contact with potable water. Belzona solutions and coatings are easy to apply and cure at ambient temperatures, allowing for rapid application and a minimum of downtime. Providing a long-lasting, effective solution, they are an excellent alternative to lengthy replacement or repair works.
Another benefit of using a coating system is that it allows you to use a coated mild steel tank as opposed to the relatively high outlay for an all stainless steel tank, thereby keeping your costs down.
How to Protect a Potable Water Storage Tank from Corrosion with Belzona
The wastewater treatment process and related activities expose concrete to a variety of damage mechanisms including:
- Physical damage
- Chemical and microbiological attack
- Freeze-thaw cycles
High relative humidity levels, the need for cold temperature curing and the requirement to keep operations running smoothly make repairs increasingly difficult.
Belzona concrete repair composites are designed to rebuild and repair damaged concrete surfaces, restoring the original profile with a simple procedure that minimises downtime and can be completed without hot work. Belzona concrete repair systems will cure in a matter of hours, achieving full mechanical hardness soon after. Specialist coating solutions can then be applied to improve resistance to the common forms of wear and corrosion, extending service life with a minimum of financial outlay
Concrete Case Study
At this water treatment plant in Scotland, two clarifiers were in need of repairs. The running track on top of the wall had been experiencing impact and abrasion damage due to the arm. The substrate was seriously damaged. However, there was only a limited shutdown window to make any repairs.
The chosen solution for this was Belzona 4131. This had three major benefits over a traditional concrete repair. Firstly, by using the Belzona material, a repair could be completed in a fraction of the time it would take to knock down the walls & rebuild them. As well as this, the material’s chemical & impact resistance prevents the original problem from re-occurring. As well as this, polymeric materials are non-porous, therefore will not allow water ingress, so freeze-thaw issues are not a problem anymore.
This blog post has summarised some of Belzona’s solutions for the Water and Wastewater industries. However, the benefit of Belzona solutions is there versatility. Even if a specific application area has not been mentioned, Belzona materials are able to be used in many locations around Water and Wastewater plants. This is thanks to the high qualities many of them exhibit, including: