P-54

1
MASTER BREWERS ASSOCIATION OF THE AMERICAS
P-54
MBAA Annual Conference October 13 15,
2011Hilton MinneapolisMinneapolis, 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
Potential Problems with Nitric/HF Acid Cleaning
Before and After (continued)
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.

• 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.

Vapor Area Deck Covers
External Spray Header Manifold
Control Panel
Cleaning 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
   1020 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.

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-acceptab
  le procedure, especially for indoor cleaning of
  304 SS metallurgies.

Post Cleaning/Passivation Steps
Before and After ChemTreat SS16
Cleaning/Passivation

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
Passivation Using Environmentally-Acceptable
Procedures

• 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.

• 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.

Quick Reference to Best Practices
Pasteurizer Water Chemistry All Compartments/All
Manufacturers
Passivation ASTM-A967
Parameter/Metric Suggested Range/Target pH
(all compartments) 7.58.6 (0.2
units) Chlorides lt150 ppm as Cl Total
Hardness lt400 ppm as CaCO3 Total M
Alkalinity lt300 ppm as CaCO3 Total Organic
Carbon lt40 ppm as TOC (zone 1) Turbidity lt
40 Ntu (zones 16) Conductivity/TDS lt3.0 x
makeup/reclaim µmhos Free Residual Halogen (non
H-H) 1.02.0 ppm as Cl2 Free Residual Halogen
(H-H) lt0.50 ppm as Cl2 Cl2 Splits
Free/Total lt0.75 ppm differential free versus
total Biocounts (Aerobic) lt103
cfu/mL Biocounts (Anaerobic) N/D in water
samples Active (Filtered) Polymer Minimum 710
ppm via polymer test Zinc gt0.5 ppm in all
compartments and reclaim
Electrical Panel and Hand Rails
Regenerative Zone Piping
External Structure

• 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.
• 3.03.2 for 400 series SS 4.55.0 for 300 series
  SS.
• Lower metal removal rate.
• 0.0010 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.