Are Stainless Steel Tanks the Best Choice to Store Caustic Soda Outdoors?

Sodium hydroxide (NaOH), also known as caustic soda or lye, is a common inorganic compound that is typically used as a strong chemical base.

Are Stainless Steel Tanks the Best Choice to Store Caustic Soda Outdoors

In liquid form, caustic soda becomes “slippery” and tends to find weak points in storage containers, and fittings, and eventually create drips and leaks.

Its corrosive and slippery nature make it tricky to store caustic soda, especially if you need to keep it in liquid form. The chemical begins to crystalize at 54 deg F, so it’s important to ensure that your storage tank maintains a temperature of at least 60 deg F. If the chemical begins to turn solid, you will have wasted chemical to dispose of, and a potentially challenging cleanup in your fittings, pumps, sensors, and plumbing.

A heat maintenance kit is essential for any tank that will be outdoors in cooler climates. The heating system is usually comprised of tank heating pads, thermostat system, polyurethane foam, and a coat of paint.

The number and size of heating pads are determined by several factors, including:

  • Size of the tank
  • Type of tank
  • Required chemical temperature
  • Ambient conditions
  • Tanks and Extreme Cold


Review the compatibility of our tanks, fitting, and gaskets with over 100 different chemicals

Stainless Steel Tanks for Sodium Hydroxide?

Stainless Steel Caustic Soda TankMany facilities use stainless steel tanks to store caustic soda. The steel walls are resistant to corrosion, the tanks can be kept outdoors, and heating kits are easy to apply. Steel tanks also cost three to four times as much as necessary.

Cross-linked polyethylene (XLPE) tanks perform as well as stainless steel, while saving your company as much as 75 percent of the cost of steel tanks.

See How XLPE Compares to Other Tank Materials

Poly Processing’s SAFE-Tank® system provides the same double wall tank system and resistance to corrosion as stainless steel, while providing benefits that steel tanks can’t offer:

  • Smaller footprint—our double-wall system eliminates the need for a large concrete berm.
  • Lower initial costs—XLPE tanks are a fraction of the cost of steel.
  • Lower long-term costs—no concrete berm means less maintenance or repair over the life of your storage system.
  • Conservation of lost chemical—if a leak occurs, the double-wall system contains any leaked chemical, preventing loss.

The SAFE-Tank also works well with a heat maintenance kit, and the double-wall functions as an additional measure against heat loss. Our engineers can work with you to determine the ideal solution to maintain proper temperatures.

Download Our SAFE-Tank Guide

Polyethylene Tanks Are the Better Business Solution

While stainless steel tanks are the common go-to solution for storing sodium hydroxide above 60 deg F, there is no advantage to steel. However, there are drawbacks that add up both in the short term and over time. For many facilities, a polyethylene chemical storage tank is the smarter cost effective solution for your business.

Get more information on sodium hydroxide storage.

Download Our Sodium Hydroxide Guide

Is your tank built for safe chemical storage?