Steel Manufacturing Blog: Keeping it Steel

Vent Hole Plugs: Aluminum vs. Zinc

Posted on Thu, Jul 24, 2014 @ 09:16 AM

Here's a quick note regarding Vent Hole Plugs. The large majority of customer requests are for aluminum Vent Hole Plugs. However, they are also available in zinc. There are several reasons a fabricator will request zinc rather than the less expensive and more malleable aluminum. The foremost reason would be potential corrosion. Mind you, we would be talking about corrosion over a very long period, possibly 20 to 30 years... but some jobs will call for the plug to be zinc.

What complicates the issue is the different manufacturing process for the aluminum and zinc plugs, and how that limits the sizes available. Aluminum plugs are cut from round bar stock. The aluminum is dimensionally stable throughout the process. The process can start with any diameter bar that can be cut to any diameter plug. zinc plugs start with liquid zinc at approximately 800˚ F which is then poured into a mold the shape of the plug.

Vent Hole PlugsAs the zinc cools, the outer surface hardens first. Like all metals, as it cools it contracts. The problem occurs when the outside is hardened and has taken its final shape, but the inside is still cooling and still contracting. The inner contraction creates vacuum pockets, which can make the plug porous.

Smaller diameter zinc plugs do not have this problem. It makes itself apparent when the plug size gets to about 11/16” diameter or larger. For this reason we can only provide zinc Vent Hole Plugs in sizes up to 5/8” diameter. Note, Vent Hole Plug diameter is always measured at the mid-line.

The Steel Supply Co. provides zinc and aluminum vent hole plugs for the steel, construction and masonry industry. We provide all different diameters, but these products can also be made-to-order for your most demanding projects. To view our vent hole plug stock, click below!


View Our Vent Hole Plug Stock

Tags: Aluminum Plug, Galvanized Vent Plug, Galvanized Vent Hole Plug, Vent Hole Plug