Secondary Containment Coating Systems for Industrial Contractors

Article 02 of 24

Defining the Service Environment Before Selecting a System

The correct containment system cannot be selected until the actual chemical, thermal, mechanical, environmental, and operational conditions have been clearly defined.

Learning Objectives

After completing this article, you should be able to:

• Identify the information required before selecting a containment system
• Explain why a chemical name alone is not enough
• Distinguish splash, intermittent exposure, pooling, and immersion
• Recognize thermal, mechanical, cleaning, and environmental demands
• Use chemical-resistance charts appropriately
• Request a written manufacturer recommendation using complete exposure information

System Selection Begins With Questions—not Products

Selecting a containment lining by habit, price, availability, or generic resin type creates unnecessary risk. “Use an epoxy” is not a complete system-selection decision. Epoxies, novolac epoxies, vinyl esters, polyurethanes, polyureas, and reinforced systems can differ significantly within the same general chemistry.

The service environment must be documented first. Only then can the owner, specifier, manufacturer, and contractor determine whether a proposed system is suitable.

The Eight Parts of a Service-Environment Definition

1. Identify Every Material That May Reach the Containment

Start with the complete chemical or product name. Trade names alone may not provide enough information. Obtain the current Safety Data Sheet, process information, supplier information, and chemical composition when available.

Do not limit the investigation to the principal material stored in the largest tank. The containment area may also receive:

• Process intermediates and byproducts
• Different materials stored in neighboring tanks or totes
• Acids, alkalis, solvents, oils, fuels, or oxidizers
• Water mixed with the released chemical
• Fire-suppression water or foam
• Cleaning solutions and disinfectants
• Maintenance fluids, lubricants, and hydraulic oils
• Reaction products created when incompatible materials mix

A Safety Data Sheet is an important hazard-communication document, but it is not normally a complete containment-lining specification. It may not define every ingredient, operating condition, or long-term compatibility requirement needed for system selection.

2. Record the Actual Concentration

Chemical concentration can change the severity and mechanism of attack. A lining listed as resistant to a dilute solution should not automatically be assumed resistant to a concentrated version of the same chemical.

Record:

• Normal operating concentration
• Maximum expected concentration
• Possible concentration during a process upset
• Concentration after dilution with water
• Concentration after evaporation of water or solvent
• Whether the material contains suspended solids or abrasive particles

Do not assume that dilution always makes an exposure harmless. Water can change how a chemical interacts with both the lining and the substrate. Selection must be based on documented manufacturer guidance for the actual solution.

3. Define Every Relevant Temperature

Chemical resistance commonly decreases as temperature rises. Elevated temperature may accelerate chemical attack, increase permeation, soften a polymer, increase thermal stress, or shorten the time available for cleanup.

The service definition should distinguish among:

• Normal liquid temperature
• Maximum process temperature
• Maximum spill temperature
• Ambient and substrate temperature
• Hot-water or steam-cleaning temperature
• Daily and seasonal temperature cycling
• Rapid thermal changes or thermal shock

“Room temperature” is not an acceptable description when a credible release could reach the containment area at a substantially higher temperature.

4. Define the Type and Duration of Exposure

A product’s suitability for splash does not establish suitability for immersion. Exposure categories must be described accurately.

Secondary containment is sometimes described as spill service because it is not intended to hold material continuously. However, an emergency, an unattended leak, limited access, or delayed response can produce extended exposure. The credible cleanup time must be defined.

5. Account for Chemical Mixtures and Exposure Sequence

Resistance to individual chemicals does not automatically establish resistance to a mixture. Combined materials can produce different chemical activity, heat, solids, or reaction products.

Exposure sequence also matters. A system may first contact a process chemical, then water, followed by an alkaline cleaner, disinfectant, or solvent. Repeated cycling can be more demanding than one isolated exposure.

Provide the manufacturer with the complete mixture and expected cleaning sequence. Do not combine separate entries from a resistance chart and assume that the combined exposure is approved.

6. Include Mechanical and Operational Demands

Chemical resistance alone does not make a lining suitable. The system must also tolerate the physical demands of the area.

• Pedestrian traffic
• Forklifts, carts, and maintenance equipment
• Dropped tools, drums, hoses, or equipment parts
• Abrasion from solids, grit, or cleaning
• Tank, pump, or piping vibration
• Movement at joints and cracks
• Hydrostatic or moisture-vapor pressure
• Pressure washing or steam cleaning
• Future maintenance and equipment replacement

A chemically resistant thin-film system may still be unsuitable where impact, abrasion, movement, or heavy traffic requires greater thickness, reinforcement, flexibility, or a separate wearing surface.

7. Consider Indoor, Outdoor, and Weather Exposure

Outdoor containment systems may be exposed to ultraviolet radiation, precipitation, standing water, freeze-thaw cycling, windblown dirt, temperature extremes, and vegetation. These conditions may affect appearance, flexibility, adhesion, cleanability, and service life.

Indoor areas can experience condensation, washdown, poor ventilation, process heat, or limited access. Below-grade structures may experience groundwater, moisture migration, and hydrostatic pressure from behind the lining.

Identify both the exposure on the face of the lining and conditions behind the lining. A material may resist the contained chemical but still blister or delaminate because of moisture moving through the substrate.

Chemical-Resistance Charts Are Screening Tools

Manufacturer chemical-resistance charts are valuable, but the rating must be read together with the chart’s definitions, footnotes, temperature limits, concentration limits, exposure category, cure requirements, and testing conditions.

Before relying on a chart entry, verify:

• The exact product or complete system tested
• Chemical name and concentration
• Maximum approved service temperature
• Whether the rating applies to splash, spill, fumes, or immersion
• Required film thickness and number of coats
• Required cure time before exposure
• Whether staining or discoloration is considered acceptable
• Whether the chart recommends direct consultation with the manufacturer

A favorable chart entry is not permission to ignore the project specification or substitute a system without written approval.

Obtain the Recommendation in Writing

A verbal statement such as “that product should work” is not an adequate basis for a high-consequence containment project. Submit the complete service conditions and request a written recommendation.

The written response should identify:

• The recommended primer, lining, reinforcement, and finish components
• Required surface preparation
• Required thickness and application sequence
• Detailing requirements for joints, cracks, penetrations, and terminations
• Maximum approved chemical concentration and temperature
• Approved exposure type and duration
• Minimum cure before chemical exposure
• Inspection and testing requirements
• Important limitations, exclusions, or maintenance requirements

A Practical Service-Environment Worksheet

Document the following before recommending or purchasing a system:

1. Facility, area, and equipment identification
2. Complete chemical or product names
3. Chemical concentrations and mixtures
4. Normal and maximum temperatures
5. Expected exposure type and maximum contact time
6. Cleanup and decontamination procedures
7. Traffic, impact, abrasion, and movement
8. Indoor, outdoor, ultraviolet, and weather exposure
9. Substrate type, age, condition, and previous treatments
10. Moisture conditions and drainage
11. Cracks, joints, penetrations, drains, and transitions
12. Required installation and return-to-service schedule
13. Applicable specification, regulation, and owner requirements
14. Name of the party authorized to approve the system

Conditions That Require Written Clarification

• The chemical identity or concentration is unknown
• The maximum spill temperature has not been provided
• The expected cleanup time is uncertain
• Multiple chemicals could mix in the containment area
• The manufacturer’s published rating does not match the actual exposure
• The specified system conflicts with current product instructions
• The substrate or moisture condition differs from the bid documents
• Required details, tests, or acceptance criteria are missing
• A substitute product or system is proposed

Technical References

• American Concrete Institute, ACI PRC-515.2-24, Selecting Protective Treatments for Concrete—Guide
• American Concrete Institute, ACI PRC-515.3-20, Guide for Assessment and Surface Preparation for Application of Protection Systems for Concrete
• Association for Materials Protection and Performance, Coatings and Linings over Concrete for Chemical Immersion and Containment Service
• Occupational Safety and Health Administration, 29 CFR 1910.1200—Hazard Communication
• Current coating-manufacturer technical data sheets, chemical-resistance guides, application instructions, and safety data sheets for the complete proposed system

Verify the current edition of every standard, regulation, technical document, and manufacturer instruction before bidding or beginning work.

Key Takeaways

• Define the service environment before selecting a product
• Chemical identity alone does not establish suitability
• Concentration, temperature, duration, and mixtures can change performance
• Cleaning and mechanical demands are part of the exposure
• Chemical-resistance charts are screening tools, not complete specifications
• Obtain a written recommendation for the actual service conditions
• Stop and request clarification when essential information is missing

Professional responsibility: The contractor should not invent missing exposure information or make unsupported chemical-resistance decisions. Obtain written direction from the owner, specifier, design professional, or system manufacturer before proceeding.

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