New and Improved Materials for Corrosion Prevention discussed in Hot Topic Hour on August 9, 2012
There has been a steady improvement in corrosion materials and their selection for power plants over the last few decades. There was one step backward when problems arose with alloy 2205. The impetus was the soaring cost of nickel and the high nickel alloys. But in the webinar yesterday we learned about the way this problem was solved. We also learned about various other materials and fabrication techniques which are helping power plants cost-effectively reduce corrosion.
Jim Ness, Corrosion Market Specialist at AOC Resins LLC, reviewed the many different applications for FRP vessels, ducts and linings. He pointed out that a variety of resins are available to deal with corrosive situations. The major limitation is temperature. Fortunately, U.S. power plants have been able to control excursions. As a result there have not been significant FRP failures. Gas temperatures are below 200°F due to the injection of slurry. As cooling towers recycle more water and discharge less, the chloride levels rise, so FRP is a good choice for the recirculation piping.
Doug Reinke, VP Sales & Marketing for Augusta Fiberglass covered the use of FRP and dual laminate process equipment. Over the last ten years, innovative equipment delivery methods have been developed and refined to enable large FRP and dual laminate equipment to be supplied to the power industry. Some impressive photos of 119 foot diameter scrubber vessels were displayed. The company can ship by barge and has delivered products to South America from its U.S. facilities.
Debajyoti (Deba) Maitra, Product and Application Development Engineer at Huntington Alloys Division of Special Metals Corporation, unveiled research findings on "Accelerated Crevice Corrosion of Duplex Stainless Steels in Wet Limestone FGD Environments." A variety of steels and alloys have been used in the construction of wet FGD systems ranging from duplex and austenitic stainless steels to highly alloyed grades of nickel-base corrosion-resistant alloys. Many absorber vessels constructed of duplex stainless steel have experienced severe corrosion, often after less than one year of operation. This attack was explored and both laboratory and field tests were conducted. Localized corrosion, especially under mineral deposits, was detected and evaluated. Samples of several grades of stainless steels and alloys were exposed in an operating scrubber vessel to determine their response to the conditions experienced in the FGD system. The good news is that super-austenitic stainless steels and some nickel-base alloys were found to be resistant. Super-austenitic stainless is in use at Arizona Public Service Cholla Station and has already logged two successful years of operation. Another FGD system with this material is being supplied in Korea.
Lake H. Barrett, Sales Manager for Sauereisen, explained that both inorganic and organic coatings have their place. However, you have to make sure you select the right lining for the temperature and corrosive conditions which will be encountered. Saureisen has been active in China and other countries as well as the U.S. He said that in China there have been more problems with temperature excursions. These have resulted in destruction of synthetic linings.
The Bios, Abstracts and Photos information is linked below.
BIOS, ABSTRACTS, PHOTOS - AUGUST 9, 2012.htm
The individual presentations are as follows: