Sodium Hydroxide Image

Sodium Hydroxide

Defying a chemical that “finds” leaks

Also known as caustic soda or liquid lye, sodium hydroxide is used to adjust pH in water and wastewater treatment and in the manufacture of chemicals, rayon, cellophane, pulp and paper, aluminum, detergents, soaps and a wide range of other products.

As for storage:

  • Sodium hydroxide is a “slippery” chemical that tries to find leak paths.

  • This chemical is extremely corrosive to tissue. It is also highly toxic if ingested.

  • If sodium hydroxide is not kept at a specific temperature, it will crystallize and go solid.

A tank system and proper fittings from Poly Processing can reduce your risk with this hazardous chemical.

Talk to a chemical storage tank expert

The Poly Processing Sodium Hydroxide System

The key to storing sodium hydroxide properly is strong, safe containment. Since the chemical is so corrosive, secondary containment is a must.

If secondary containment is already available, the IMFO® tank is recommended. IMFO® systems are ideal for Sodium Hydroxide Systems because their flange is actually a molded part of the tank, and not an insert that could leak or fail.

The IMFO® also ensures long-term performance of the overall system, since it eliminates the need to drill into the sidewall of the tank and install a mechanical fitting, which can create a maintenance issue for this chemical.

When secondary containment is not available, a SAFE-Tank® can meet this requirement. This “tank within a tank” extends the margin of safety by providing a system with 110% secondary containment.

The tank’s high-density crosslinked polyethylene construction means greater strength. It is so strong, in fact, that Poly offers a warranty of five full years on all tanks.

For additional information on storing sodium hydroxide, including recommended storage tanks and components, download our Sodium Hydroxide Guide below.  

Download our Sodium Hydroxide Guide   

Chemical Resin Type Specific Gravity Rating Fitting Material Gasket Material Bolt Material
Sodium Hydroxide 50% XLPE 1.65 PVC EPDM 316SS


Tank Specifications

Tank options include: 

High-density crosslinked polyethylene (XLPE) construction for maximum strength

OR-1000™ antioxidant inner surface 

Integrally Molded Flanged Outlet (IMFO®) for complete drainage 

SAFE-Tank® design for "tank-within-a-tank" protection 

Recommended System Components

SAFE-Tank® Double Wall Tank System

SAFE-Tank® Double Wall Tank System

Secondary containment: SAFE-Tank® if concrete containment is not available. 

Alternative: PPC secondary containment basin or other secondary containment suitable for chemical, of adequate size for use

IMFO® Fittings

IMFO® Fittings

Fittings: IMFO® eliminates the need for confined space entry.

PTFE Expansion Joint

PTFE Expansion Joint

Plumbing: requires flexible connections to allow for lateral and vertical tank contraction and expansion, and to reduce vibration stress. 

SAFE-Surge® Manway Cover

SAFE-Surge® Manway Cover

Venting: SAFE-Surge® manway cover is recommended on pneumatically loaded systems to support tank longevity.

Technical Overview

NOTE: Heating pad and insulation are highly recommended to prevent crystallization of the chemical.

IMFO® Vertical Flat Bottom of XLPE:

  • 230–13,650 gallons

  • 1.65 spg rating

Non-IMFO® alternatives :


  • 55–8,700 gallons

  • 1.65 spg rating for primary tank

  • Spg ratings for secondary tanks must be equal to primary tank.

  • All other tank sizes must equal primary tank spg rating.

Standard Vertical Flat Bottom XLPE:

  • 30–13,650 gallons

  • 1.65 spg rating

Alternative secondary containment: PPC secondary containment basin or other secondary containment suitable for sodium hydroxide, of adequate size for use

Plumbing: Requires use of flexible connections with fittings on lower third of sidewall. See Fittings & Accessories for flexible connections options.

  • Expansion joints must meet the following minimum requirements:
    • Axial Compression ≥ .67˝
    • Axial Extension ≥ 0.67˝
    • Lateral Deflection ≥ 0.51
    • Angular Deflection ≥ 14°
    • Torsional Rotation ≥ 4°

Venting: See Venting Chart

Foundation: PPC IMFO® tank pad or smooth concrete, asphalt or steel foundation designed to accommodate IMFO®, SAFE-Tank® or vertical tank

Temperature: Product should not exceed 100°F at delivery or during storage or drop below 50°F to prevent damage to the chemical. Contact Customer Support if chemical is to exceed 100°F.

Lid: SAFE-Surge® manway cover for pneumatically loaded tanks; bolted manway cover for all other applications

Options: Restraint systems for wind and seismic, level gauges, ladders, heating pads, insulation, mixer mounts, OR-1000™ for NSF-61 certification and engineering stamp