Polyethylene vs. Steel Storage Tanks: What's the best choice?

When it comes to choosing a chemical storage solution, you won’t find a more aesthetic option than stainless steel tanks. Steel tanks are popular in breweries and other applications where they’re on public display. The tanks look shiny and clean, and they contribute to the interior design of the space. Steel tanks also have a reputation for being one of the most reliable chemical storage systems on the market.

That’s why you may be surprised to discover that cross-linked polyethylene (XLPE) chemical tanks can match a steel tank’s performance, at just a quarter of the cost. 

There are two major types of steel tanks available in today’s market: mild steel and stainless steel. In this article, we’ll look at the pros and cons and bust the myth that steel tanks are a better choice than XLPE tanks for chemical storage.

Mild steel Tanks Vs. Polyethylene Tanks

Mild steel tanks are normally used in the mining industry to store sulfuric acid. If you’re storing a concentration of 98 percent sulfuric acid, your steel tank can perform for many years. However, once the concentration is diluted below 93 percent, sulfuric acid becomes corrosive to steel and your chemical tank’s life expectancy can be significantly compromised.

Poly Processing’s XLPE tanks can dependably store sulfuric acid at many concentration levels. Combined with our innovative OR-1000™ System, our proprietary polyethylene tanks deliver unmatched chemical resistivity as well as engineered load tolerances for heavy weight chemicals.

XLPE's molecular bonding and thick tank wall, provides the necessary structural strength that can more than handle the chemical’s heavy weight. This is especially critical in the bottom third of the tank sidewall, where the highest hoop stress levels are concentrated.

In addition, Poly Processing tanks are designed to store up to 98% concentration of sulfuric acid and is the only company with a complete chemical storage tank system certified to the NSF 61 standard. The OR-1000 System and all associated fittings adhere to these stringent specifications as well.

Stainless Steel Tanks Vs. XLPE Polyethylene Tanks

Stainless steel storage tanks are the traditional choice for breweries, clean-in-place applications, and caustic soda storage. But business-savvy organizations are realizing the benefits of using crosslinked polyethylene storage tanks.

For businesses that are looking to increase profits and scale to the next level, XLPE tanks provide four important advantages:

1. Initial cost—On average, polyethylene tanks cost a fraction of what a comparable stainless steel tank costs.
   
   
2. Longevity—Crosslinked polyethylene tanks are built for longer useful life and have very little maintenance associated with them.
   
   
3. Seamless - Crosslinked polyethylene tanks are seamless, homogenous tank systems. Stainless steel tanks are welded. A 6000 gallon stainless steel tank can have up 70 yards of welded seams.
   
   
4. Delivery time—An XLPE tank can typically be ordered and delivered within three to four weeks. A stainless steel tank requires 20 weeks or more for delivery.
   
   
5. Scalability—Poly Processing tanks are available in a variety of sizes from 55-gallon to 13,650-gallon tanks.

Breweries

Traditionally, stainless steel or other metal tanks have been used for every part of brewery operations, from storing the materials to making beer. For small-batch, fast-growing craft brewery operations, polyethylene tanks are the ideal choice to help you scale quickly and respond to market demands. As the craft brewery grows, XLPE tanks can be manufactured and delivered quickly, are cost-effective and available in a variety of sizes.

Clean-in-place Applications

Stainless steel tanks are popular for clean-in-place applications as well. High purity acids and cleaning agents are often needed to clean beverage or food grade equipment to ensure quality and prevent bacterial growth. Our XLPE, OR-1000, and specialty food and beverage grade fittings give you a customized clean-in-place storage solution.

Caustic Soda Storage

Sodium hydroxide (NaOH), also known as caustic soda or lye, is a strong chemical base. Its corrosive and slippery nature makes it tricky to store, especially if you need to keep it in liquid form.

Many 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. However, steel tanks cost two to three times more than necessary, and they don’t provide better performance than XLPE tanks.

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

• Lower initial costs—XLPE tanks are much more cost effective to that of steel tanks.
  
  
• Smaller footprint—Our double-wall system eliminates the need for a large concrete berm.
  
  
• 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.
  
  
• Seamless - Crosslinked polyethylene tanks have no seams. They are molded as a one piece tank with no weldments like steel tanks.

With the SAFE-Tank, maintaining proper temperature is easy with a heat maintenance kit. The double-wall tank design also helps to naturally reduce heat loss. Our engineers can help you to determine the best solution for keeping caustic soda in the right temperature range.

The Best Tank Solution for Your Growing Business

Steel tanks may be the most attractive solution for chemical storage but looks can be deceiving. Polyethylene provides the same (or better) performance as steel storage systems. At the same time, XLPE tank systems are a much more cost effective solution. For growth-minded businesses, cross-linked polyethylene is the clear choice for chemical storage.

Find out more about choosing the best tank material in our chemical tank buying guide.