Food Engineering logo
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • TOPICS
  • EXCLUSIVES
  • MEDIA
  • FOOD MASTER
  • EVENTS
  • RESOURCES
  • EMAGAZINE
  • SIGN UP!
cart
facebook twitter linkedin youtube
  • NEWS
  • Latest Headlines
  • Manufacturing News
  • People & Industry News
  • Plant Openings
  • Recalls
  • Regulatory Watch
  • Supplier News
  • PRODUCTS
  • New Plant Products
  • New Retail Products
  • TOPICS
  • Alternative Protein
  • Automation
  • Cannabis
  • Cleaning | Sanitation
  • Fabulous Food Plants
  • Food Safety
  • Maintenance Strategies
  • OEE
  • Packaging
  • Sustainability
  • More
  • EXCLUSIVES
  • Plant Construction Survey
  • Plant of the Year
  • Sustainable Plant of the Year
  • State of Food Manufacturing
  • Top 100 Food & Beverage Companies
  • MEDIA
  • Podcasts
  • Videos
  • Webinars
  • White Papers
  • EVENTS
  • Food Automation & Manufacturing Symposium and Expo
  • Industry Events
  • RESOURCES
  • eNewsletter
  • Custom Content & Marketing Services
  • FE Store
  • Government Links
  • Industry Associations
  • Market Research
  • Classified Ads
  • EMAGAZINE
  • eMagazine
  • Archive Issue
  • Advertise
Food Engineering logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Food Engineering logo
  • NEWS
    • Latest Headlines
    • Manufacturing News
    • People & Industry News
    • Plant Openings
    • Recalls
    • Regulatory Watch
    • Supplier News
  • PRODUCTS
    • New Plant Products
    • New Retail Products
  • TOPICS
    • Alternative Protein
    • Automation
    • Cannabis
    • Cleaning | Sanitation
    • Fabulous Food Plants
    • Food Safety
    • Maintenance Strategies
    • OEE
    • Packaging
    • Sustainability
    • More
  • EXCLUSIVES
    • Plant Construction Survey
    • Plant of the Year
    • Sustainable Plant of the Year
    • State of Food Manufacturing
    • Top 100 Food & Beverage Companies
  • MEDIA
    • Podcasts
    • Videos
    • Webinars
    • White Papers
  • FOOD MASTER
  • EVENTS
    • Food Automation & Manufacturing Symposium and Expo
    • Industry Events
  • RESOURCES
    • eNewsletter
    • Custom Content & Marketing Services
    • FE Store
    • Government Links
    • Industry Associations
    • Market Research
    • Classified Ads
  • EMAGAZINE
    • eMagazine
    • Archive Issue
    • Advertise
  • SIGN UP!
Latest headlinesProcessing

Maintenance

Know the causes of stainless-steel corrosion in retorts and take practical steps to prevent corrosion

Retorts represent a large investment, so take the right steps from the very beginning to maximize the life expectancy of these devices and your ROI

By Jeff Arthur
Stress corrosion cracking - viewed under scanning electron microscope
Stress corrosion cracking, viewed under an electron microscope, slowly wreaks havoc with stainless steel devices—whether a small stainless steel thermocouple or a large retort. Photo courtesy Allpax
December 5, 2019

Because stainless steel is easily cleaned and does not rust under normal conditions, it is the preferred metal for food processing machines used in wet environments. A little-known fact about stainless steel is that it is prone to unique types of corrosion when the metal is exposed to a specific set of environmental factors. These corrosion-producing conditions can exist during the operation of stainless-steel batch retorts and are not easily realized or recognized. Unless steps are taken to identify, reduce, or eliminate the causes of corrosion, batch retorts may have their service lives cut short, resulting in production disruptions and the need for early replacement of affected vessels.

Modern retorts and their internal wetted parts are commonly made from 300-series stainless steel. Understanding the root causes of corrosion in stainless-steel retorts can be complex; however, there is a common theme in how most of the problems start. The standard retort has an internal environment of high temperature and pressure created by steam, water, and oxygen—all of which are normal operating conditions for a retort. When excessive harmful chloride ions are present—inside or even on the outside of the retort—regardless of how they were introduced, the ions act as a catalyst for starting and accelerating corrosion in stainless steel during the retort cycle.

The terms chloride ions or chlorides are not to be confused with or solely blamed on the use of chlorine as a sanitizer. Chlorides are ions comprised of the element chlorine with a negative charge and can also be associated with salts. While chlorine sanitizers do add chlorides to the retort water, chlorides can come from many sources ranging from the incoming municipal retort water supply, a recycled water storage tank, product on the outside of containers, residual salt brine from an improper water softener regeneration system, or even chlorides from insulation materials, to name a few. Basically, when stainless steel is exposed to high temperatures, high stresses, and excessive amounts of chlorides, a corrosion reaction from the chlorides can start.

Three types of corrosion can weaken stainless steel

There are three different types of corrosion normally found in stainless-steel retorts. The most insidious is stress corrosion cracking (SCC), sometimes called chloride stress corrosion cracking. Once stainless steel begins cracking, the damage is permanent and not repairable. Highly stressed areas of steel inside the retort system are normally affected first. When high levels of chlorides, adequate oxygen, water, and high temperatures combine, the SCC corrosion reaction can start.

SCC infections weaken stainless steel, causing it to become brittle. The fact that metal continuously expands and contracts through repetitive heating and cooling cycles accelerates SCC when the corrosive conditions exist. There is no remediation for SCC-affected metal once it has started. Removing a weakened section and welding in a new one is often ineffective as it just adds more heat and stress to the already affected area. The retort becomes un-repairable when the problem is in advanced stages.

Crevice corrosionThe second type of corrosion found in stainless steel retorts, crevice corrosion, is caused by concentrations of chlorides filling small spaces between two parts or voids where water has stagnated. Only one part needs to be stainless steel, the other can be stainless or another material such as a gasket. As the retort cycle temperature and pressure increases, water combined with a concentration of chlorides works its way into small cracks lacking the free flow of oxygen over the area and the corrosion reaction starts. These crevices can be as small as .005 inch (0.127mm) when they start and grow to large pockets that are inches in size, eroding the metal away. As the retort fills and empties cycle after cycle, the concentration of chlorides in the cracks rises and becomes even more corrosive, enlarging or undermining the crevice and weakening the metal.

Pitting corrosionThe third type of stainless-steel corrosion commonly found in stainless retorts is pitting. When pitting corrosion has progressed, it is visible to the naked eye and sometimes is in open areas that are easier to see—but not always. Pitting does not always follow a set of rules where one area is pitted, and one area is not on the same steel surface. If no metal surface protection is present, small pits in the steel start to develop when the metal surface is exposed to ample amounts of chlorides, hypochlorite (chlorine), or bromide ions in the environment. Pitting in advanced stages can aggressively erode thick steel, causing leaks.

All three of the corrosion reactions mentioned above have chlorides as a common denominator in starting and continuing the corrosion within the retort and retort utility piping system.

How do chlorides continue to be in the retort and go unnoticed?

Chlorides in the retort cannot be seen by the naked eye, only the by-products of corrosion and then only by trained personnel. Water and steam chemistry tests can detect the level of chlorides in the retort water. Part of the problem is realizing there is one. In many cases where a corrosion monitoring program is not in place, the corrosion problem is not found until much damage is already done, causing production or maintenance issues. Understanding the root causes of corrosion in stainless-steel retorts requires an in-depth knowledge of the equipment, the water chemistry, how the production line operates, including compliance with federal regulations, and an understanding of the corrosion mechanisms. This set of skills can be spread across many departments within a food manufacturing plant and is not always located in one central place or area of responsibility.

Recommendations for addressing stainless-steel corrosion

For plant operations to have a sustainable long-term retort system that meets the Code of Federal Regulations with the lowest possible corrosion rates, there needs to be an effective water treatment system, including chloride and pH control of the water, along with training of operations personnel and preventive maintenance monitoring.

The first step in remediation is an audit of the filling operation to understand the products being retorted and how the packages are conveyed into the retort. Testing the chemistry of the incoming steam and retort water should also be undertaken. And an interior inspection of the retorts, piping, and the retort utility support system should be performed by a team of auditors, under the direction of certified retort specialists, and should include water treatment experts and chemical suppliers. The auditors should make recommendations on:

  • Filling operations and maintenance training as they relate to retort corrosion
  • Treatment of the incoming steam and retort water based on chemistry analysis
  • The type and setup of water treatment and corrosion control monitoring and chemical application systems, including passive monitoring utilizing metal corrosion coupons and/or active electronic monitoring
  • Potential repairs and/or modifications to retorts and the utility support system based on current level and/or rates of corrosion

After corrective actions are in place, follow-up inspections, either from the auditing group or internally trained maintenance/plant engineering personnel, should occur on a quarterly basis to ensure correct procedures and practices are followed, and that results are within expectations. Routine audits, water treatment analysis, retort evaluation, and training are investments needed to keep retort room workers safe from corrosion-initiated hazards, produce products of the highest quality possible, and maintain production at high efficiency levels throughout the projected life of the retorts.

For information on the issues of corrosion in stainless steel and the Allpax 40-point inspection initiative, call 888-893-9277, or visit Allpax at www.Allpax.com.

KEYWORDS: retort

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Fe author allpax jeff arthur
Jeff Arthur, Technical Director, Allpax, has over 31 years of experience in the industrial food processing equipment industry, primarily associated with the design, manufacturing and sales/customer support of in-container, thermal sterilization/processing equipment.

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • Global Organic Food & Beverage Market to Grow

    Global Organic Food & Beverage Market to Grow

    With a CAGR of 12.07%, Bonafide Research estimates this...
    Latest headlines
  • skilled MEP worker

    Predicting Food and Beverage Manufacturing Trends for 2024

    The two words that should be kept in mind are labor and...
    Automation
    By: Derrick Teal
  • cleaning and sanitation

    The basics of cleaning and sanitation in food plants

    Sanitation maintains or restores a state of cleanliness...
    Cleaning | Sanitation
    By: Richard F. Stier
Subscribe For Free!
  • eMagazine
  • eNewsletter
  • Online Registration
  • Manage My Preferences
  • Customer Service

OT Cybersecurity Vulnerabilities in Food Manufacturing Facilities

OT Cybersecurity Vulnerabilities in Food Manufacturing Facilities

Understanding Impacts of OT Cybersecurity Events in Food Manufacturing

Understanding Impacts of OT Cybersecurity Events in Food Manufacturing

Food Plant Openings and Expansions April 2025

Food Plant Openings and Expansions April 2025

FA&M 2025 in Rewind

FA&M 2025 in Rewind

More Videos

Popular Stories

Conagra Logo

Conagra Brands to Sell Chef Boyardee Brand to Hometown Food Company

Salt

FDA to Amend Standards of Identity to Include Salt Substitutes

Vilter IHP in plant

Industrial Heat Pumps: Sustainable Energy Solutions for Now and the Future

CHECK OUT OUR NEW ESSENTIAL TOPICS

Alternative ProteinAutomationCleaning/SanitationFabulous Food Plants

Food SafetyMaintenance StrategiesOEE

PackagingSustainability

Events

June 5, 2025

Mass Customization Driving Innovation in the Food and Beverage Industry

The food and beverage industry is at the nexus of transformative global manufacturing trends, driving a shift toward personalized, customer-centric solutions. 

June 5, 2025

How Cafe Spice Uses Automation to Propel Private Label

Learn about Cafe Spice’s new, state-of-the-art, highly automated manufacturing facility in Beacon, New York. 

View All Submit An Event

Products

Recent Advances in Ready-to-Eat Food Technology

Recent Advances in Ready-to-Eat Food Technology

See More Products

Plant of the Year

Related Articles

  • Industrial hoses

    How to Prevent Your Hoses from Compromising the Quality of Your Food

    See More
  • EU Food waste

    'Use by…,' 'Best before…,' confusion causes 10% of food waste in the EU

    See More
  • cereals-563796_1170x658.jpg

    Innovations to Take Center Stage in the Oat Milk Market as the Demand for Flavored Drinks Depicts an Increase

    See More

Related Products

See More Products
  • food crime.jpg

    Food Crime: An Introduction to Deviance in the Food Industry

  • Rice-Engineering-Website-Cover-439x600.jpg

    Advances in Science & Engineering of Rice

  • seafood.jpg

    Innovative Technologies in Seafood Processing

See More Products

Events

View AllSubmit An Event
  • June 1, 2009

    Food Plant of the Future: Using Design to Increase Productivity and Drive Down Unit Costs

    On-Demand: The need for food and beverage processors to drive down unit costs never ends. How can new/retrofitted plants be designed to optimize productivity?
  • September 29, 2011

    Food Plant of the Future: Anticipating the Next Generation

    On-Demand: Exclusively for thought-leaders in food and beverage processing facility management, Food Plant of the Future webinars are presented by Hixson, a leading design and engineering firm of food processing facilities in North America.
View AllSubmit An Event
×

Elevate your expertise in food engineering with unparalleled insights and connections.

Get the latest industry updates tailored your way.

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Food Master
    • Store
    • Want More
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletter
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

Food Engineering logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Food Engineering logo
  • NEWS
    • Latest Headlines
    • Manufacturing News
    • People & Industry News
    • Plant Openings
    • Recalls
    • Regulatory Watch
    • Supplier News
  • PRODUCTS
    • New Plant Products
    • New Retail Products
  • TOPICS
    • Alternative Protein
    • Automation
    • Cannabis
    • Cleaning | Sanitation
    • Fabulous Food Plants
    • Food Safety
    • Maintenance Strategies
    • OEE
    • Packaging
    • Sustainability
    • More
  • EXCLUSIVES
    • Plant Construction Survey
    • Plant of the Year
    • Sustainable Plant of the Year
    • State of Food Manufacturing
    • Top 100 Food & Beverage Companies
  • MEDIA
    • Podcasts
    • Videos
    • Webinars
    • White Papers
  • FOOD MASTER
  • EVENTS
    • Food Automation & Manufacturing Symposium and Expo
    • Industry Events
  • RESOURCES
    • eNewsletter
    • Custom Content & Marketing Services
    • FE Store
    • Government Links
    • Industry Associations
    • Market Research
    • Classified Ads
  • EMAGAZINE
    • eMagazine
    • Archive Issue
    • Advertise
  • SIGN UP!