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ARMORTHANE PROTECTING YOUR WORLD

PROTECTING YOUR WORLD

ARMORTHANE PROTECTING YOUR WORLD

Tank Lining:
Coatings for Steel
& Concrete Tanks

How tank linings work, which lining fits water, fuel, chemical and wastewater tanks, what prep and testing a lining needs, and when spray polyurea is the right choice.
Tank Lining Quotes

Leaking, corroding or due for a new lining? Get it quoted.

Tell us the tank type, size and what it holds. We will connect you with a certified applicator who can inspect and quote the lining.

  • Tank type: steel, concrete or other
  • Diameter and height, or volume
  • What the tank stores, and temperature
  • Current lining and condition
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20 mils
Thin-film vs thick-film line in API 652
API 652
NSF 61
Required for drinking-water contact
NSF/ANSI/CAN 61
SP 10
Usual minimum blast for steel linings
SSPC / AMPP
Seconds
Polyurea gel time: thick walls in one visit
Product data sheets

A tank lining has one job: keep what is inside the tank away from the tank, and keep the tank from leaking. When a lining fails, steel pits through from the inside or concrete is eaten away, and you usually find out late. We make spray polyurea and the equipment that applies it, and our applicators line water, fuel, chemical, agricultural and wastewater tanks every week. This guide covers how to choose a tank lining, how it should be installed, and what to demand in testing.

Quick answer

Tank lining is a coating or membrane applied to the inside of a tank to stop corrosion, chemical attack and leaks. Thin-film epoxies suit many water and fuel tanks; thick-film systems such as spray polyurea, glass-flake epoxy or rubber suit abrasion, movement, chemical attack and older, pitted tanks. Any lining is only as good as its prep (usually near-white blast on steel), film thickness and holiday testing. Potable water tanks must use NSF/ANSI/CAN 61 certified products.

What's in this guide
  1. 1Why tanks need linings
  2. 2Lining types compared
  3. 3Lining by tank type
  4. 4Step-by-step process
  5. 5Why polyurea
  6. 6FAQ
Start here

Why tanks need linings

Bare steel tanks corrode wherever water collects, and water collects in fuel tanks, chemical tanks and water tanks alike: in the bottom, at the water line and in the vapor space under the roof. Concrete tanks crack, leak and lose surface to acids, and in wastewater service hydrogen sulfide turns into sulfuric acid that attacks the concrete above the liquid line.

Steel

Internal corrosion

Pitting at the floor and the water line, plus condensation corrosion in the vapor space and roof.

Concrete

Leaks and acid attack

Shrinkage cracks, cold joints and acid attack on the concrete surface and rebar.

Product

Contamination

Rust and coating debris in fuel, chemicals or water, and taste and odor problems in potable systems.

Compare

Tank lining types compared

LiningTypical thicknessStrengthsLimitsTypical tanks
Thin-film epoxyUp to 20 milsProven, economical, good chemical resistanceBrittle; needs sound steel; slower cureFuel and water tanks in good condition
Thick-film epoxy / glass-flake20–60 milsLow permeability, bridges minor pittingRigid; long cure before serviceCrude and product tank bottoms, chemical tanks
Spray polyurea40–125+ milsSeamless, flexible, impact and abrasion resistant, fast return to serviceNeeds plural-component rig and skilled crew; check temperature and chemical chartsWater, wastewater, agricultural, secondary containment, many chemical and fuel tanks
Polyurea hybrid40–125+ milsLower cost, fast setLess chemical resistance than pure polyureaNon-critical water and agricultural tanks
Rubber lining1/8–1/4 in. sheetExcellent for abrasive slurries and some acidsLabor-intensive seams; heat limitsMining slurry, acid storage
FRP lining60–250 milsStructural reinforcement for damaged tanksLabor-intensive, rigidOld steel tanks needing structural repair
Thickness ranges are typical; API 652 classifies tank bottom linings above 20 mils as thick-film.
Field noteOn older steel tanks with pitting, thin films often fail at the pits because they cannot bridge them evenly. Fill or weld the deep pits, then use a thick-film lining.
Which tank

Choosing a lining by tank type

Drinking water

Potable water tanks

Only NSF/ANSI/CAN 61 certified lining products, applied to the certified thickness and cure. See water tank coating.

Fuel

Fuel and petroleum tanks

Fuel-resistant linings on tank bottoms and lower shells; follow API 652 for aboveground storage tank bottoms. See fuel tank liner.

Chemical

Chemical storage tanks

Match the lining to the chemical, concentration and temperature using the manufacturer chemical resistance chart.

Wastewater

Wet wells and treatment tanks

Polyurea over prepared concrete stops acid attack and infiltration. See wastewater coatings.

Agriculture

Manure, fertilizer and water tanks

Abrasion and chemical resistant, fast-cure linings that return tanks to service quickly.

Concrete

Concrete tanks and vaults

Flexible linings that bridge shrinkage cracks. See concrete tank waterproofing.

Do it right

The tank lining process, step by step

  1. Inspect and clean out

    Drain, ventilate and clean the tank under confined-space procedures. Inspect for pitting, cracks and structural damage.

  2. Repair

    Weld or fill deep pits on steel; route and fill cracks and repair spalls on concrete.

  3. Surface preparation

    Abrasive blast steel to the specified standard, usually SSPC-SP 10 near-white, with the specified anchor profile. Mechanically prepare concrete to sound, open, dry substrate. See surface preparation.

  4. Control the climate

    Dehumidify and heat as needed so steel stays at least 5°F above the dew point from blast to coating.

  5. Prime and stripe coat

    Apply the specified primer, then brush stripe coats at welds, edges and penetrations.

  6. Spray the lining

    Apply the lining in multiple passes to the specified thickness, including floor-to-wall transitions and nozzles.

  7. Test and document

    Measure film thickness, holiday test 100% of the lining, check adhesion on test areas and record cure before return to service.

Where we fit

Why polyurea for tank lining

Spray polyurea gels in seconds, so an applicator can build a thick lining on walls and roofs without sags, in one shift, and most tanks can go back in service within hours to a day, depending on the product and the service. The film stays flexible, so it tolerates thermal cycling, settlement and minor substrate movement that crack rigid linings.

  • Seamless: no laps or seams where leaks start.
  • Thick in one visit: 40 mils and up in multiple passes, which also bridges minor surface defects.
  • Fast return to service: less downtime and fewer days paying for confined-space crews.
  • Tough: resists impact from agitators, debris and cleaning equipment.
Know the limitsCheck the chemical resistance chart for your exact product and temperature. Some strong solvents, concentrated acids and hot service need specialty linings or a different chemistry.
Tank lining

Stop leaks and corrosion from the inside.

A certified ArmorThane applicator can inspect your tank, recommend a lining for what it holds, and spray it with full holiday testing.

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FAQ

Tank lining questions

What is tank lining?

Tank lining is a coating or membrane applied to the interior of a tank to protect it from corrosion, chemical attack and leaks, and to protect the stored product from contamination.

What is the best lining for a steel tank?

It depends on what the tank holds and its condition. Thin-film epoxy suits many water and fuel tanks in good condition. Thick-film systems such as spray polyurea or glass-flake epoxy suit pitted tanks, abrasion, movement and many chemical services.

How long does a tank lining last?

A correctly specified and installed lining commonly lasts 10 to 20 years or more. Life depends on prep, film thickness, the stored product, temperature and how the tank is cleaned and maintained.

Can polyurea be used in potable water tanks?

Only polyurea products certified to NSF/ANSI/CAN 61 for drinking water contact, applied and cured as the certification requires. Ask for the certification listing before work starts.

How long is a tank out of service for lining?

Prep usually takes the most time. Spray polyurea itself cures fast enough that many tanks return to service within hours to a few days, compared with longer cure times for many epoxies.

Do tank linings need holiday testing?

Yes. A single pinhole can concentrate corrosion. Linings should be holiday tested over 100% of the surface, with defects repaired and retested.

AT
Written by the ArmorThane technical team. We have manufactured polyurea, polyurethane and polyaspartic coatings, spray foam and plural-component spray equipment in Springfield, Missouri since 1989. We make coatings and spray equipment. Lining selection for regulated service should follow the tank owner specification and the product data sheet.

Sources

  1. API 652, Linings of Aboveground Petroleum Storage Tank Bottoms. api.org
  2. NSF/ANSI/CAN 61, Drinking Water System Components. nsf.org
  3. AWWA D102, Coating Steel Water-Storage Tanks. awwa.org
  4. AMPP (formerly SSPC and NACE) surface preparation standards. ampp.org

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