Does 316 stainless steel rust iso#

The photograph shows the clean face of a 316 coupon exposed to the 1,000-ppm NaDCC solution in Figure 8. In Figure 7, the photograph above shows pitting beginning on the edge of a304L coupon exposed to undiluted household bleach. The photograph shows corrosion starting near the center of the face of a 304L coupon when exposed to the 1:50 household bleach solution in Figure 6. In Figure 5, the photograph shows rust floating in the beaker containing 304L coupons exposed to the 1:10 household bleach solution. The corrosion spread across the coupon surface due to the rust falling down the coupon face (Figure 3). Notable pitting is shown in the photograph above on the edge of a 304L coupon exposed to the 1:10 bleach solution. There was pitting, corrosion and staining of both 304L (Figures 3 – 4) and 316 1:10 bleach solutions and full-strength bleach solutions. The 304L and 316 coupons were clean in the water, 200 ppm and 1,000 ppm NaDCC solutions. The 316 coupon in the 1:10 household bleach solution also exhibited corrosion, but to a lesser extent.īy eleven days, the glass beaker sides containing the 304L coupon in the 1:10 bleach solution were contaminated with rust. After four days, the 304L coupon in the 1:10 household bleach solution exhibited definite corrosion, pitting and staining as shown in Figures 1 – 2. However, the undiluted bleach samples were maintained an additional four weeks until metal was deposited on the glass beakers.Ī description of the progression of the coupons corroding in the test solutions follows. The study was conducted over eight weeks.

Does 316 stainless steel rust iso#

The beakers were maintained under an ISO Class 7 environment. Noted differences include changes in color, rust and corrosion, pitting, gas evolution while the coupons were submerged in solution, and metal deposition on the glass surface of the beaker.Īfter inspection, fresh solutions were prepared for each coupon-solution combination, and the coupons were placed back in their original beakers.

Any differences were documented (Table 2) and photographed, as shown in Figures 1 – 17. The coupons were removed from the beakers daily and wiped dry for visual inspection. The beakers were then covered with plastic wrap. Three coupons were submerged in 400-mL beakers containing 250 milliliters of one solution listed above ensuring complete coverage of the coupons. The solution concentrations, formulations and appearance are compiled in Table 1. Six solutions were prepared daily with deionized water (18 MΩ RODI) using commercially available Clorox® bleach and commercially available tablets containing NaDCC. The objective of this study is to compare the corrosion caused by bleach and NaDCC solutions at various concentrations on two common types of stainless steel surfaces and to demonstrate the advantages of using NaDCC over bleach as part of a disinfection program.įor this study, 18 stainless steel 316 (316) and 18 stainless steel 304L (304L) 2” x 2” x 1/8” coupons were obtained from GlobePharma. It also kills a large spectrum of microbes, is widely available and is easy to use. Sodium dichloroisocyanurate (NaDCC) is a bleach alternative available in a solid tablet form. Even with these drawbacks, bleach is commonly used because it kills a large spectrum of microbes, is widely available, and is easy to use. However, bleach is known to be corrosive to metals and can cause damage to some plastics. Liquid bleach (sodium hypochlorite solution) is used as a disinfectant in pharmaceutical, bioprocessing, and medical device facilities commonly at a 1:10 dilution (one part bleach combined with nine parts water). Coupons exposed to NaDCC solutions at levels of 187 and 937 ppm active chlorine did not show corrosion, suggesting that NaDCC can serve as an effective alternative disinfectant to liquid bleach. Bleach diluted at 1:10 and 1:50 showed corrosion of the stainless steel. The rate and degree of corrosion exhibited by the stainless steel coupons were compared. Two commonly used types of stainless steel coupons were exposed to household bleach and sodium dichloroisocyanurate (NaDCC) solutions over a period of eight weeks. Bleach is known to be corrosive to metals that are commonly found in pharmaceutical, bioprocessing, and medical device work environments.