Having identified corrosive feedwater as the root of scaling and corrosion in its coal-fired boilers, waterpark and family resort Warmbaths, a Forever Resort, contacted industrial boiler manufacturer and water treatment solutions provider Allmech to aid in the restoration of two boilers.

When one of the boilers was inspected, corrosion and scaling were immediately evident, and significant capital expenditure was identified as necessary to bring the boiler back to an acceptable standard.

Forever Resorts engaged Allmech to review its water treatment setup and provide a second opinion.

When Allmech assessed the site, a demineralisation plant was supplying feedwater to the mid-pressure coal-fired boiler. Allmech MD Lionel Maasdorp explains that, on the surface, highly purified water may seem like the ideal choice.

However, demineralised water absorbs minerals from anything that is in contact with it. In a carbon steel boiler system, that can accelerate corrosion in the boiler shell, tubes and condensate lines.

“Considering the water was being used for a mid-pressure coal-fired boiler, we did not agree with the demineralised water. Water that clean can be corrosive in the boiler and pipes,” says Maasdrop.

Low pH levels compounded the problem, particularly in the condensate lines, where oxygen-related corrosion was evident. Steam traps were clogging with rust particles. The resort was in the process of replacing some metal pipework with polyvinyl chloride to mitigate the effects, but when the boiler was opened, it was clear that acid wash and repairs to boiler tubes were required. Forever Resorts decided to relook their system requirements and setup and asked Allmech to assist.

Change in Strategy

After analysing the incoming raw water, Allmech recommended discontinuing the demineralisation process and instead repairing and optimising the site’s softeners. This reduced “unnecessary” chemical expenditure and allowed for a more appropriate treatment strategy.

The team started using the Allmech A103, a blended boiler treatment designed for mid-pressure systems. Maasdorp says that the A103 performs several functions simultaneously; an oxygen scavenger removes dissolved oxygen, the pH booster stabilises and elevates alkalinity, a polymer keeps suspended solids in suspension so they can be removed through controlled blowdown, and a vapour-phase component helps to protect condensate lines from corrosion.

Allmech also implemented weekly check-ins to monitor how the new approach was working. Total dissolved solids were monitored, blowdowns adjusted and chlorine and pH levels in the condensate tracked closely. Over time, test results began to shift in the right direction and pH levels increased. Rust particles in the feed tank decreased, while corrosion stabilised.

Visible Results

When the boiler was inspected after the first year under Allmech’s treatment programme, visible corrosion had already reduced. Maasdorp says some debris remained, but this likely ori- ginated from previously damaged condensate lines.

The original-equipment manufacturer recommended another acid wash. Allmech did not believe this was necessary, but the procedure was carried out.

At the most recent inspection, the difference was clear.

“The tubes were spotless. There was only evidence of old scale that had flaked off in a hard-to-reach area. There were no signs of excessive corrosion, and the particles that had previously been present in the feed tank were no longer there,” he says.

A clean boiler eliminates the need for further acid washing – a harsh and destructive process. Avoiding these interventions extends asset life.

Operational Impact

Warmbaths boiler manager Jean Nel says the improvements have been significant.

“We saw a lot of changes. The boiler was more efficient, with less coal usage. There [is] less corrosion in the boiler and less scale detected on the inner tubes, [since] Allmech took over the boiler water treatment,” he explains.

The resort has also seen improved chemical efficiency compared to its previous setup and Nel believes the risks to longevity have been effectively addressed.

“Without a good water treatment partner, you can damage your boiler and tubes. It can cause a lot of damage in the long run. The value of Allmech’s service is up to standard. They are . . . always there to assist us. We can say with an open heart we are happy to have them on our side,” says Nel.

Partnership Approach

Maasdorp, meanwhile, credits the site team for their role in the turnaround.

“I am always proud when a client’s team works well with our staff. A good team working together helps to look after a company’s assets and livelihood by reducing unnecessary costs,” he says.

With the right treatment strategy and disciplined monitoring, boiler water chemistry becomes an asset protection tool rather than a recurring repair risk, he avers.