How to Install a Bulkhead Fitting in a Tank

A bulkhead fitting (also called a tank adapter or tank fitting) creates a leak-tight connection through the wall of a tank so you can attach pipe, a valve or a hose. The body passes through a hole in the tank wall, a gasket seals against the inside wall, and a nut tightens against the outside. This guide covers how to size the hole, install the fitting and test it for leaks.

Before You Buy

  • Check the chemical compatibility for your materials before you buy. If you are unsure, contact us and speak to one of our experts.

Before You Install

  • Cross-check the spec sheet and the installation instructions from the manufacturer of your bulkhead before you begin.
  • Make sure you have your necessary tools handy:
    • Drill
    • Appropriate diameter hole saw
    • Grease pencil or marker
    • Scrap plastic or wood for testing your hole
    • Wrench or torque wrench (as specified by the fitting manufacturer)
  • Ensure your tank is in good condition and is compatible with your new bulkhead.
  • Drain the tank below the fitting location.
  • Check your bulkhead for any defects or missing pieces.

Installation Checklist

  1. Drain the tank and mark the center point for the fitting on the outside of the tank. Choose a flat area away from ridges, bumps, corners and tight curves, so the entire gasket can seat against the tank wall. Check the manufacturer's spec sheet for the minimum tank radius and maximum wall thickness for your bulkhead size.
  2. Drill a test hole in scrap material and check the fit of the bulkhead. The bulkhead should pass into the hole with no more than 1/16 inch of side-to-side play. Proper diameter is determined by measuring the outside thread diameter of the fitting body and checking the manufacturer specification sheets.
  3. Once you are sure about the hole size, drill the hole in the tank and put the bulkhead (including the gasket) through from the inside of the tank. The gasket always goes on the inside of the tank. For bolted fittings such as Rhino, first clamp the face plate centered over the hole, mark each stud hole, remove the plate and drill the stud holes to the size given in the manufacturer's instructions.
  4. From outside the tank, thread the nut onto the bulkhead and tighten it to the manufacturer's specification. Do not overtighten. Overtightening can bulge the gasket, strip the threads or crack the fitting. If you have installed a siphon tube, make sure it is facing the correct way.
    • Hayward BFA/BFAS (PVC, CPVC, PP): hand tight plus 1/4 to 1/3 turn. Left-hand thread; follow the arrow on the nut and hold the body by its flats. No lubricant on the threads.
    • Banjo TF (PP): TF050/TF075 15-20 ft-lbs; TF100/TF125 30-40 ft-lbs; TF150/TF200 60-70 ft-lbs; TF220 70-90 ft-lbs; TF300 110-130 ft-lbs.
    • Rhino stainless (bolted): torque wrench, crossing pattern, gradually. Seals at 15-20 ft-lbs; do not exceed 25 ft-lbs. No air wrench.

    Important: Always follow the instructions supplied with your fitting.

  5. Connect your piping. Follow the thread-sealing instructions for your fitting, since manufacturers differ: Hayward specifies PTFE tape on the male pipe threads and no pipe dope or liquid sealant on PVC, CPVC, PP or GFPP threads, while Banjo specifies a soft-set sealant on the fitting's inside threads. Do not overtighten threaded pipe into a plastic bulkhead, and support the adjoining pipe so the bulkhead does not carry its weight.
  6. Due to expansion and contraction of the tank walls, it is best to use flexible connections between tank fitting and rigid pipe or pump.
  7. Water test your tank to check for leaks. If you find a leak, drain the tank below the fitting, correct the cause and test again. Common causes are a nut that is not tight enough, a gasket material that is not compatible with the chemical in the tank, threads that are not sealed properly, or a cracked fitting from overtightening or damage.

Can You Install a Bulkhead Fitting Without Access to the Inside of the Tank?

The bulkhead and tank fittings covered on this page, including bolted and boltless stainless steel fittings, are inserted through the hole from inside the tank, with the gasket on the inside wall. If you cannot reach the inside of your tank, contact us and we can help you find an option for your application.

Frequently Asked Questions About Bulkhead Fittings

Q: Does the bulkhead gasket go on the inside or outside of the tank?
A: On the inside. Insert the fitting from inside the tank with the gasket against the inside wall, then tighten the nut from the outside.

Q: What size hole do I drill for a bulkhead fitting?
A: Check the manufacturer's spec sheet for your size. Drill a test hole in scrap material first; the fitting should pass through with no more than 1/16 in. of side-to-side play.

Q: Can I install a bulkhead fitting on a curved tank?
A: Choose the flattest area you can so the whole gasket seats against the wall, and check the spec sheet for the minimum tank radius for your fitting size.

Q: How tight should a bulkhead fitting be?
A: Tighten to the manufacturer's specification and no more. Overtightening can bulge the gasket, strip the threads or crack the fitting.

Shop Bulkhead Fittings and Tank Accessories