I had a lot of galvanized steel pipe and fittings lying around so I decided to build a high power steel pipe air cannon. This cannon is a lot safer than PVC ones because steel pipe is rated for compressed air, unlike PVC. This design also allows for interchangeable barrels.

Supplies

Galvanized steel pipe and fittings

Bench vise

Thread sealant

PVC primer and cement

Self-tapping screw

PVC pipe and fittings.

Large hose clamp

Hacksaw

Step 1: Air Tank

The air tank consists of two 1.5" x 12" steel pipe nipples connected by a coupling and sealed at one end with an end cap.

Step 2: Barrel

The barrel consists of 48" of 3/4" PVC pipe connected to a bushing and 1" male adapter. It is okay to use PVC pipe for the barrel because it is not under constant pressure. I added a self tapping screw to prevent ammunition from being pressed too far.

Step 3: Fill Valve

The fill valve is a gas line pressure test tool. I replaced the included 15 psi gauge with a 160 psi gauge. This allows the air cannon to be filled using a bike pump or air compressor.