P-54 MASTER BREWERS ASSOCIATION OF THE AMERICAS MBAA Annual Conference October 13 – 15, 2011 Hilton Minneapolis Minneapolis, MN “ Safe and Environmentally-Friendly Method for On-Site Cleaning and Repassivation of 304 Stainless Steel Pasteurizer Components Jack Bland, ChemTreat, Inc. Scott Pavlich, Barry Wehmiller Abstract With few exceptions, virtually all of the tunnel-type pasteurizers in modern breweries are 304 stainless steel (SS) construction. While this metallurgy offers excellent corrosion resistance in brewery packaging area environments, it is critical that stains or deposits not be allowed to remain on internal or external pasteurizer surfaces. Any debris or deposition on the 304 SS surface will rapidly reduce the corrosion resistance. Hot, humid conditions on the packaging floor, coupled with volatile hypohalous amines from the pasteurizer water treatment program, will amplify the corrosion rate underneath any deposits on the stainless steel surface. Previous standards for deposit removal and repassivation of 304 SS involved the use of hydrofluoric and nitric acid. This procedure is no longer acceptable as an on-site method due to strict environmental regulations. ChemTreat, in conjunction with one equipment manufacturer, has developed an effective, safe, and environmentally-friendly alternate process for on-site cleaning and passivation of brewery pasteurizers with 304 SS metallurgy. This poster will detail the process and show before and after photographs of a variety of internal/external pasteurizer surfaces. Conclusions will summarize best practices for maintaining the passivation of 304 SS metallurgy following cleaning. Background Modern brewery pasteurizers are primarily constructed of 304 SS and passivated during the construction process at the manufacturing facility. Recent, raw SS plate may not meet previous standards and premature iron oxide (rust) can be exfoliated onto internal and external pasteurizer SS surfaces. This phenomenon is especially prevalent where CIP standards have been relaxed on 304 SS pasteurizers. Hydrofluoric/nitric acid soak was standard for many years in SS passivation. HF/Nitric is no longer an environmentally-acceptable procedure, especially for indoor cleaning of 304 SS metallurgies. Passivation Using Environmentally-Acceptable Procedures American Society of Testing and Materials produces ASTM 967-A: Alternate method using citric acid for cleaning and passivation of 300 series SS. ChemTreat refines ASTM method in field tests with Barry Wehmiller to develop a product that approaches similar results formerly obtained only with HF/Nitric acid soaking during the manufacturing process. Product has undergone extensive field testing in 5 separate applications for validation of results. Passivation ASTM-A967 Citric Acid…. Removes free iron from the SS substrate. Achieves a passive surface. Meets QQ-P-35C (QQP-35C replaced by ASTM A967 [AMSQ-P-35]. Tested and approved by the aerospace, medical, machining/manufacturing and food industries. Brightens 300 SS series alloys. Excellent appearance on 400 series SS. Operates at a higher pH. 3.0–3.2 for 400 series SS; 4.5–5.0 for 300 series SS. Lower metal removal rate mils/minute per surface (performed on 303 SS). Accepted as an alternative to nitric acid/sodium dichromate for AMS- QQ-P-35 Type II on 303 SS (less chance for pitting. Cleaning Steps Post Cleaning/Passivation Steps PPE Required 1.Clean off any surface debris and rinse with hot/warm water. 2.Spray SS-16F on area to be cleaned. Let stand 10–20 minutes (surface must remain wetted with cleaning solution). 3.Use soft nylon brush or Scotch Brite ™ pad to remove rust. 4.Rinse with hot/warm water to remove all product from 304 SS area. 5.Repeat process if any visible iron oxide remains. 6.Dry with absorbent towels. Tyvek ® lightweight coverall suit or rubber apron. Safety glasses with side shields or face shield. Rubber gloves. 1.Thoroughly rinse specific area with hot water between each cleaning step. Use ambient water to wash residue into the floor drain. 2.Dispose of PPE worn during cleaning each day. 3.If disposing the secondary container (ex., spray bottle), you must triple rinse the container prior to disposing. 4.Inspect area to be cleaned before/after cleaning/passivation. Recommendations for Minimizing the Need for Future Cleaning/Repassivation Routine washdown of all components to prevent deposition on SS surfaces. Periodic spot cleaning of any recurrence of deposits on SS metallurgy. Adherence to “Best Practices” for water chemistry guidelines. Potential Problems with Nitric/HF Acid Cleaning Violent reaction with non-SS metallurgy: pump housings/floor drains/pump impellers. Toxic fume release from above reactions. Delayed toxicity effects from fume inhalation/skin contact. Self-contained breathing equipment required for MSDS compliance. Spent solution disposal issues. Quick Reference to Best Practices Pasteurizer Water Chemistry: All Compartments/All Manufacturers Parameter/MetricSuggested Range/Target pH (all compartments)7.5–8.6 (±0.2 units) Chlorides<150 ppm as Cl Total Hardness<400 ppm as CaCO 3 Total ‘M’ Alkalinity<300 ppm as CaCO 3 Total Organic Carbon<40 ppm as TOC (zone 1) Turbidity<40 Ntu (zones 1–6) Conductivity/TDS<3.0 x makeup/reclaim µmhos Free Residual Halogen (non H-H)1.0–2.0 ppm as Cl 2 Free Residual Halogen (H-H)<0.50 ppm as Cl 2 Cl 2 Splits Free/Total<0.75 ppm differential free versus total Biocounts (Aerobic)<10 3 cfu/mL Biocounts (Anaerobic)N/D in water samples Active (Filtered) PolymerMinimum 7–10 ppm via polymer test Zinc>0.5 ppm in all compartments and reclaim Before and After ChemTreat SS16 Cleaning/Passivation Electrical Panel and Hand RailsRegenerative Zone PipingExternal Structure Before and After (continued) Vapor Area Deck CoversExternal Spray Header ManifoldControl Panel