The Steel Supply Company has added 5 new sizes to our stock of Galvanized Vent Hole Plugs. Zinc Vent Hole Plugs are now available in sizes 13/16”, 7/8”, 15/16”, 1”, 1-1/16”.
The predominant Aluminum Vent Hole Plug is also in stock from diameters 1/4” up to 3”.
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Fig. 1
While both Aluminum Plugs and Zinc Vent Hole Plugs are used for the same purpose there are some differences in performance. When using a Vent Hole Plug the steel would naturally be recently galvanized. The cured galvanize coating is approximately 90% zinc. Using an Aluminum Vent Hole Plug creates a situation where dissimilar metals are interacting. Steel fabricators always use caution in these situations however the voltage involved in this case is very low and usually not important to the process or lifetime of the product. It is estimated it could take as much as 20 years before even a minute sign of corrosion would appear.Nonetheless some architects and engineers require the Galvanized Vent Plug material match the Hot Dip Galvanized Coating. This is commonly the case where;
- The steel will be located very near a caustic atmosphere such as body of salt water, in a food or chemical processing plant, or confined areas with high vehicle traffic such as tunnels.
- Locations where continuous or frequent vibration would be present.
- Areas with very extreme high to low temperature variations of approximately 140˚F or more.
Fig. 2
The Zinc Vent Hole Plugs involve several factors the user should be aware of. The first is slightly higher cost. The second is the cavity on the inside. (Fig. 1) The cavity is the result of the Zinc Vent Hole Plug being molded to shape as opposed to the Aluminum Plug which is machined from bar stock.
Fig. 3
It is important for the Steel Fabricator to know the depth of the cavity and be sure to drive in the plug beyond that depth. Otherwise when the excess is ground away the plug could break through to the cavity. (Fig. 2)
The depth of the cavity is typically 1/2 the height of the plug. This does vary with differences in plug diameter, so it is a good idea to check. Cavity depth will not vary from plug to plug of the same diameter. (Fig. 3)
