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Preventive Maintenance For Hot Water Tanks

“It was a call I’ve gotten dozen of times,” said Warren Brand, President of Chicago Tank Lining Sales, Inc. “It was from one of the top, most recognized hotels in Chicago and they had a large hot water tank that had sprung a leak.

When a hot water tank leaks, it’s primarily in the bottom, where, in most cases, large amounts of rust, sludge and sediment have collected. The tank corrodes underneath the sludge and then, eventually, rusts through and leaks.

The leak is typically small, perhaps the size of the head of a needle. It may drip, or shoot out as a small stream, like from a spray bottle. However, due to the corrosion that has occurred in this area of the tank bottom, the steel immediately surrounding the perforation is typically very thin. So an engineer may clean away the tank insulation and just try and clean the area with a wire brush or rag, which may actually increase the rate of the leak.

“ While our insurance company doesn’t allow us to give advice on issues such as this,” said Warren, “we can share what others have done in these circumstances.”

One of the things that we’ve heard is very simple and successful, is to hammer in a piece of wood. I’ve heard that the wood will conform to the shape of the hole and then expand as it absorbs the water.

A well-known chocolate company in the Chicago area had a vertical condensate return tank that had leaked numerous times. It was about 8’ tall and 3’ in diameter. “The tank looked like a porcupine,” recalls Warren. “There must have been a half dozen or more pieces of wood hammered into this tank to keep it from leaking.”

The challenge was that the company was running three shifts and couldn’t shut down for more than 12 hours and only on a Sunday. Warren told the engineer they could fix these leaks, externally, in less than 12 hours.

External repairs with some very specialized, quick curing, imported epoxy and UV-cured fiberglass were finished, much to the amazement of the engineer. But, because the engineer had chosen not to corrosion protect the interior of the tank, it could not be properly repaired and within time they had to install a new one. Given the option to line the new tank, once again they company decided against it.

“ It never ceases to amaze me,” said Warren, “that engineers will spend money on a perfectly good tank that typically comes with a one-year guarantee, but then not spend money to line it, which then comes with either a 5- or 10-year, non-prorated guarantee. It’s like buying a new car that’s not painted, then buying another one in 2 years because the old one rusted away.”

Warren related that they have the ability to line any tank as long as it is structurally sound. The problem is that now, because it has leaked, and it is an ASME rated tank, it must be repaired by a certified welder.

“ We probably repair 20 leading hot water tanks a year,” said Ed Hoveke, President of Hudson Boiler. “The process is straightforward,” he explained.

“ We cut out the leak, and put on a rolled, flush patch to keep the tank an ASME certified vessel,” said Ed. Following the repair, the tank is pressurized to its normal operating pressure to make sure the leak has been properly repaired. “And then we’ll give the customer the paperwork that the tank was repaired to ASME code.”

Ed said that most of the leaking tanks Hudson repairs are either bare steel or concrete lined.

The average cost to repair even a small leak is between $3,000 and $5,000 and takes about two days. “Normally, the tank repair we do is a temporary repair unless the tank is relined,” said Ed.

The problem is corrosion, Warren added. Even though the repair is done properly, the cause of the perforation remains - corrosion.

While the price of lining a tank can be quite costly, in almost all cases, it’s a one-time preventive expense that maintains an asset (the tank) indefinitely.

“ We lined a 7’ x 14” hot water tank for a hospital in Indiana in 1986,” Warren said. “The engineer inspects the tank every year and the coating is fine and the tank not only has not leaked, but is not corroding.”

Using coatings as preventive maintenance in the petrochemical industry is common place. For some reason, that concept has not translated well into the commercial sector.

Everyone knows there’s enormous value to preventive maintenance, and it’s absolutely critical for ASME rated tanks because the repairs are so expensive. Further, if the tank corrodes too much, it must be replaced.

The other advantage of coating for preventive maintenance is that it can be scheduled. “If a tank leaks, then you’re working in emergency mode,” said Warren. “If you schedule a tank lining, you have weeks or months to plan.”

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