Replacing carbon steel with Outokumpu LDX 2101® stainless resulted in a significant reduction in waste stream and longer useful life.
PVI Industries LLC selected Outokumpu LDX 2101® stainless to replace carbon steel in their commercial water heaters, a move that has resulted in a significant reduction in the manufacturer’s waste stream as well as a jump in the useful life of their water heaters. The company also received the 2014 Texas Environmental Excellence Award for Pollution Prevention.
PVI, based in Fort Worth, Texas (USA), serves large commercial end-users like hotels, schools, hospitals, and stadiums. PVI water heaters can be as large as 37 feet by 8 feet and contain as much as 4,500 gallons of water. Most PVI water heaters use coil, but plate can be used on the larger heaters.
In North America, water heaters have a carbon-steel based tradition. Domestic, potable water contains oxygen that creates iron oxide when it comes into contact with carbon steel. PVI had been using electroless nickel plating to reduce corrosion in their water heater tanks. The process was generating about 1.3 million pounds of waste a year. Depending on the application, this process achieved a useful life expectancy of five to fifteen years for each water heater.
The PVI team, limited by ASME certifications necessary for their water heaters, began looking for ways to reduce waste. “We started by looking at what materials ASME had certified. We were aware of stainless steel as a material for corrosion resistance, but some grades are not ideal for potable water applications,” reports Chris Bollas, PVI President. Eventually his team’s research led them to Outokumpu and the duplex grades.
LDX 2101 offers a solution
“We identified a couple of duplex grades and found favorable characteristics in Outokumpu’s LDX 2101®. But the grade wasn’t yet certified for water heater applications,” Bollas explains. “We believed the material was something that would accomplish our goals, because stainless steel doesn’t require any coating or plating.” A prototype, test Unit #1, was built using Outokumpu’s lean duplex LDX 2101 and then underwent accelerated life testing. The initial testing started in 2009 when Unit #1 was put through the equivalent of 30 years of normal life use at highly elevated temperatures of about 190°F. Using the results from test Unit #1, PVI approached the ASME seeking approval to use LDX 2101 in production water heaters. The Outokumpu datasheets for the grade were part of this presentation.
Five years after development, Unit #1 is still operational. The company has since produced more than 3,000 units, all but five are still in operation. The company now warranties standard duplex water heater tanks for up to 25 years. Despite all the benefits in using stainless steel over carbon, there is no change in the cost of the water heaters for customers. The additional cost of the stainless steel is offset by the savings from no longer coating and plating the carbon steel material.
Moving to duplex stainless steel reduced PVI’s waste stream to nearly zero. The efforts were recognized by the State of Texas at the 2014 Environmental Excellence Awards where PVI received the honor for Pollution Prevention. “We are thrilled to be recognized in the largest industrial state in America as the #1 green company in this area, and it is a sustainable footprint we expect to carry forward for years to come. Our experience started with a desire to have a more sustainable production operation. But this quickly expanded to a broader mission. There is a huge movement in the marketplace for materials that follow a longer life principle. And this parallels with PVI’s belief. In Outokumpu, I know we have a business partner who shares that core value,” Bollas concludes.