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Poly Tank Sidewall Fittings: What You Need To Know

Selecting the right sidewall fittings for a poly chemical storage tank is crucial. The proper fittings ensure optimum function and maximum life of the polyethylene tank. Proper sidewall fittings avoid tank leaks and spills. Selecting sidewall fittings purely based on cost can lead to an expensive mistake. Let’s explore the three types of sidewall fittings and when they should be used in tank configurations.

3 Types of Sidewall Fittings

  • Bulkhead - This is an inexpensive compression type fitting. It can be installed on the sidewall,  dome or  or for use as an overflow. Since bulkhead fittings must be installed from the inside of the tank, tank entry is required for maintenance or repairs. Bulkhead fittings are not recommended for tanks over 3000 gallons or over 6 feet in height,  Over time, this fitting "creeps," causing the nut to loosen. Regular monitoring for drips is critical.
     
  • Flange - Flange fittings are available in  many different materials of construction.  Bolted flange fittings are installed from the tank exterior, allowing repair and maintenance without entering the tank. The bolt heads are encapsulated in polyethylene, providing chemical resistance. However, the bolt entry points and the fitting itself allow for numerous possible leak points.
     
  • The B.O.S.S. Fitting® - This is a streamlined one-piece fitting without bolts. The B.O.S.S. Fitting® connects to the tank with a single gasket to greatly minimize the potential for leaks. A ring with welded studs, available in stainless steel, titanium or alloy C-276 is injection molded with polyethylene around it providing a one piece fitting with a single sealing point. The B.O.S.S. Fitting® is the fitting of choice for high profile applications like Sodium Hypochlorite and Sulfuric Acid.

Another important consideration for tank fittings is to use flexible fittings on the lower third of the tank to allow for tank expansion and contraction during tank fills and emptying of the tank

Look beyond the price when selecting tank fittings. Consider tank safety and ensure longer tank useful life with the right sidewall fittings.

For any questions or more information about sidewall fittings, please download the fittings reference chart, or contact a Poly Processing chemical storage system specialist.

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Topics: Fittings and Accessories