Corrosion Resistance Gets Renewed Attention as Stainless, New Coatings Move into Market
Maintenance costs, particularly for labor, are increasing, and the traditional material specified for piping and valve systems – painted carbon steel – is changing as end users search for solutions to minimize maintenance and increase reliability. “The presence of corrosion creates specific issues, particularly with uninsulated valves and controls, that must be managed by those in the refrigeration industry,” said Bob Czarnecki, a member of the International Institute of Ammonia Refrigeration board of directors. “Designers must consider corrosion issues as portions of most refrigeration systems will operate below ambient dewpoint, and operators must provide ongoing maintenance to mitigate the presence of corrosion.”

The upcoming ANSI/IIAR-6 Standard for Inspection, Testing, and Maintenance of Closed-Circuit Ammonia Refrigeration Systems speaks to the industry’s awareness of corrosion and what needs to be done.

Traditionally, corrosion problems have been met by keeping the valves painted, but that is an expensive, laborintensive process. Other solutions now available include use of stainless steel, which does not corrode over the typical useful lifespan of a valve, and proprietary coatings that protect against corrosion, providing operators with choices to balance initial cost with ongoing maintenance expenses.

“Valves in industrial refrigeration applications are the life of a refrigeration system and what allows the system to operate and be maintained. The minute a valve does not work, it can equal temperature loss, product loss, downtime, and even create safety-related problems that need to be immediately mitigated.”

– Jim Hower, sales director of industrial refrigeration for Danfoss

More efficient design and maintenance decisions that make the best use of personnel can help improve operations given the industry-wide labor shortage. As the labor shortage in industrial refrigeration worsens, facility managers are looking for new ways to free existing personnel by eliminating maintenance functions requiring staff hours that could be used for higher-level tasks.

“Painting is a constant maintenance headache from our end. It takes time and money, and we could do other things,” said Chris Greiner, utilities and refrigeration tech lead at a large grocery distribution center located in central Pennsylvania.

By eliminating the need to paint, noncorroding materials and finishes allow operators to have employees spend their time on tasks that improve their systems’ overall operation. Greiner said a refrigeration operator/technician’s time would be better spent on preventive maintenance, such as calibrating temperature, pressure and ammonia detectors, testing safety systems, and replacing belts, changing oil filters and lubricating the equipment. Time could also be spent cleaning the refrigeration equipment, physically observing the refrigeration compressors, evaporators and condensers to pick up on subtle changes in noises and vibrations that could be leading to an issue or monitoring operation and making adjustments to the control system, which would reduce energy usage and unnecessary equipment wear.

“Also from a safety aspect, some of the valves could be located at locations [that are difficult to access and could create hazards],” Greiner said. “From an environmental point of view, the less paint we have to use the better for the environment and the person doing the painting.”

Jim Hower, sales director of industrial refrigeration for Danfoss, noted that corporate food processing and cold-storage end users have a finite amount of resources. “Spending money to staff full-time refrigeration operators just to maintain and service refrigeration valves is no longer an option in many cases. Operators need to be highly skilled, multi-disciplined, and there is a huge shortage in the industry,” he said.

“Valves in industrial refrigeration applications are the life of a refrigeration system and what allows the system to operate and be maintained,” Hower said. “The minute a valve does not work, it can equal temperature loss, product loss, downtime, and even create safety-related problems that need to be immediately mitigated.”

Without valves, refrigeration systems wouldn’t be possible. “They control what happens in the system. From both a safety standpoint and functionality and maintenance standpoint, the valves are absolutely critical,” said Chuck Taylor, president of CRT Design.

A typical industrial refrigeration system may have hundreds of valves that automatically open and close daily to maintain building or product temperatures, and shutoff valves are what allow portions of the system to be serviced independently while the rest of the system continues to function, Hower said.

Inspectors have a good reason for caring about valves because they must function properly in the event of an emergency.

Nick Nechay, president of Independent Refrigeration Services Inc., said valves are often the forgotten piece of industrial refrigeration systems. “They’re usually in an area that is on the roof or somewhere that no one is looking at every day,” he said. “No one thinks about them until they don’t work.”

Nechay added that everyone is working to avoid external corrosion as an issue. Refrigerated facility owners are taking a new approach to maintenance, making operational decisions and specifying equipment for long-term efficiency.

Dave Schaefer, chief engineer at Bassett Mechanical and a member of the International Institute for Ammonia Refrigeration board of directors, said the most significant advantage to the latest technologies is less maintenance and reliable performance. “There is more and more interest due to mechanical integrity concerns,” Schaefer said.

Harold Streicher, vice president of business development for Hansen Technologies, said Hansen has developed its Anti-Corrosion Technology to minimize the risk of corrosion. “We want to help make the asset last as long as it can and improve its mechanical integrity as it relates to Process Safety Management,” he said, adding that Hansen’s proprietary ACT coatings will last longer than zinc plating and may in some cases approach the expected life of the valve. “It greatly extends the life to first-service.”

Eric Johnston, director of process safety management for American Foods Group, has been using Hansen’s ACT coating for a little more than a year. Johnston said he was interested in the coating for American Foods Group’s plant with smokehouses.

“It is a really corrosive environment with the lactic acid in the air,” he said. “We were having a lot of issues with corrosion on the outside of the valves.”

Johnston said that formerly new valves would experience corrosion within six to eight months of installation. “We’d have to clean it off and paint it. We’d use a nice two-part epoxy, and it would last six months to a year,” he said.

Today, American Foods Group has installed seven control banks with the ACT coating and said he has seen good results. “We are just over 18 months on the first valves and there is no rust,” he said, adding that if he gets two years out of the valves before having to paint them, the ACT coatings will have proven to be economical.

proven to be economical. For Johnston, corrosion creates a food-safety issue even if it isn’t a mechanical issue, while Bassett’s Schaefer said specific applications, such as a spiral freezer, are ideal candidates for new coatings or stainless steel. “You wouldn’t want rust flakes getting in food products,” he said.

Taylor said that from a corrosion standpoint, the corrosion is normally more of an appearance issue than a safety and functionality issue. “It isn’t usually a danger issue where it is going to rust through,” he said.

The industry is experiencing higher standards for facility visibility from customers and regulators, which emphasizes the need for properly maintained systems. Greiner agreed that even if corrosion isn’t creating a mechanical issue, it gives the perception the system isn’t adequately maintained. “I don’t like for an inspector to come in and look at my system and see [corrosion]. They see that, and it becomes a perception issue,” he said.

Greiner said corrosion on valves is a big issue for the distribution center, which serves more than 200 stores. “Most of our valves are outside on the rooftop. We try to keep up with everything for OSHA standards and PSM,” he said, adding that the company is always doing maintenance to keep corrosion at bay.

The distribution center where Greiner works has both painted and plated valves. As valves go through their normal heating and cooling cycles, metal expands and contracts, which causes paint to crack over time. “It peels off, and it is always wet, so that creates opportunity for corrosion,” Greiner said.

Another option is stainless steel, which involves cost and availability trade-offs.

Greiner said he would like to go to stainless steel valves, but they aren’t available in all of the sizes he needs. “I’m hoping in the future we could have some stainless valves for every application or size and have them be affordable enough that people would go for it,” Greiner said.

Johnston said he too has looked at stainless steel valve options but said cost can be an issue and they don’t come in larger sizes needed for industrial refrigeration.

Cyrus Shank Co. offers stainless steel options in all but three of its valves that are up to one-and-a-half inches. The remaining sizes are in the process of getting certified.

Nechay said he has seen a push from customers who want stainless steel valves in their space, particularly those focused on food safety. “They don’t want to deal with rusting carbon steel valves in a production space,” he said, adding that because there is added cost, it would only work for customers that are willing to pay the premium expense.

Mike Effrein, a sales engineer for Hantemp Controls, said the use of stainless steel is a growing trend in industrial refrigeration. “Industrial refrigeration facilities typically serve the food and beverage market,” he said, adding that stainless steel is easier to keep clean than painted surfaces and less prone to surface contamination. “Maintaining a clean and hygienic working facility is critical. Because stainless steel is corrosion-free, it is the go-to material for wash-down areas in such facilities.”

Hantemp Controls manufactures stainless steel ball valves, control valves, check valves, gauge valves, flanges and float switches. In addition to reducing maintenance expenses, stainless steel can provide added strength benefits because its physical properties allow it to be rated for higher pressures and lower temperatures. Due to the types of valves Hantemp manufactures and their functionality, Hantemp has been able to reduce weight through the use of stainless steel.

Despite its advantages, a large number of clients aren’t taking advantage of stainless steel options, Taylor said. “We spec thousands and thousands of valves and very few spec the stainless,” he said. “It is primarily because people don’t see the value of the corrosion prevention compared to the cost [premium].”

Today stainless valves can cost three to four times more than traditional valves. “If you get down to one-anda-half to two times the cost, it would probably [become more acceptable],” Taylor said.

Manufacturers have been responding to the market trend of corrosion-resistant products not only with coatings, but also by introducing expanded stainless steel product lines at more competitive price points as the volume continues to grow. Hower said Danfoss has realigned pricing to be less than two times the price of carbon steel back in early 2018 recognizing this trend and seeing the opportunity.

The increased cost of stainless steel valves is a consideration when designing the system, so it is the end user who has to weigh the decision. For Greiner, the cost of stainless would be acceptable if he could get the sizes he needs. “To me, it wouldn’t be so much an ROI I’m interested in. If you put stainless in, you know it is going to get a return,” he said.

The cost of a valve not working usually far exceeds the unit’s purchase price, which is why quality products are favored in this industry, Hower said. “The valves need to perform hundreds or thousands of times flawlessly in order to not cause a maintenance problem that requires human operator intervention,” he said.

Less corrosion results in less maintenance and greater serviceability, Czarnecki said. He added that coatings are becoming more popular and offer a less expensive option to stainless steel.

Facilities can spec stainless steel valves while still using carbon steel piping. However, on new builds locations typically spec stainless steel pipes if they are opting for stainless steel valves. “In the past, this would have been done with a mechanical or flanged connection, but weld-in style valves have recently become very popular due to their low leak potential. This application would require a transition weld carbon-tostainless, but this should not be an issue for a qualified contractor,” Nechay said.

Danfoss’s Hower said the company is extending the life of products in industrial refrigeration systems in multiple ways. “Some of this is through life-cycle testing and redesign, and some of it is through material choices and upgrading to more durable designs compared to what was traditionally available to the market,” he said.

Danfoss offers corrosion-resistant coatings, such as zinc, forged carbon steel bodies instead of cast steel, and stainless steel components and valves, Hower said.

Zinc coatings on valves do extend the life of the valve and system by providing a more durable surface treatment capable of not corroding and have a much higher adhesion rate than traditional industrial paint. “Zinc is a sacrificial layer. It gives itself up instead of the iron,” Streicher said.

However, zinc-coated valves do require painting because the ammonia can react with the zinc and discolor it, Taylor said.

Cyrus Shank Co. offers carbon steel valves with a black-oxide coating, which can help fight corrosion. The black-oxide coating is impregnated with oil to give it more corrosion resistance. Turco said customers can place a corrosion resistant paint on top of the black-oxide coating.

Cyrus Shank also offers painted ductile iron valves along with aluminum options, but Turco said he would always recommend stainless steel valves because they generally provide the most corrosion resistance because of their high amount of chromium.