Actual weight, theoretical weight, light-to-gauge, heavy-to-gauge, G-30 versus G-90 — what do these terms have to do with the price of galvanized steel paid by a contractor? Everything! The HVACR industry has always been a price-sensitive business for the contractor — be it residential or commercial applications. Competition is tough. Given today's business climate and foreign products, one might suggest that competition is even tougher. So know your business costs accurately; it's a no-brainer. The contractor must be an expert manager of both labor and material costs. Let's focus here on materials and, in particular, on buying galvanized steel.
First of all, let's cover a few basics. Take “gauge,” for example. The galvanized sheet gauge used to fabricate ductwork is specified in codes and standards. Say 24 gauge is required; this could represent a galvanized sheet that is .0236 inches to .0316 inches thick. The nominal thickness for 24 gauge is .0276 inches or right in the middle between minimum and maximum. The theoretical weight of 24-gauge galvanized sheets or coils is based on nominal thickness — an important point.
Then there's a zinc coating to protect steel from rust. The protective shield offered by “galvanizing” is directly proportional to the weight of the zinc applied per-unit-area of steel sheet. The greater the weight of the coating, the greater and longer the protection. It's that simple. The American Society for Testing and Materials standard A653 stipulates that steel sheets coated with 0.9 ounces of zinc per square foot have a classification of G-90. Those coated with 0.6 ounces per square foot have a G-60 classification. Once again, codes and standards specify the galvanized coating required.
Using these basics, let's consider the day-to-day buying practices that may be encountered.
Contractor No. 1 believes he is buying actual weight on coils, but the basis for his bill is on theoretical weight. This can result in differences in poundage, price and material by as much as +/-15 percent. The ONLY way to verify the weight or material being received is with a scale.
Contractor No. 2 may be sold light-to-gauge, or below the minimum thickness. Light-to-gauge can result in more sheets per coils for the processor and, therefore, a lower cost per sheet. However, these products may not meet industry and code minimum-thickness requirements for that gauge. All the steel you purchase should have the actual thickness determined with a micrometer.
Contractor No. 3 encounters a product that is heavy-to-gauge. The result is a coil that, when compared to a similar coil specified at the near nominal gauge thickness, has far less material yield; so although the 100-weight cost used for billing is less, the actual cost per square foot is more.
Contractor No. 4 might be sold something represented as a G-90 galvanized coating, yet the contractor receives G-60 or G-30/40. Cost differentials are substantial. Liabilities can be high, too, if a job has a specification of G-90 and something else is installed. This can result in a job being refused by an inspector or engineer, thus requiring the replacement of all materials at the contractor's expense, with the loss of materials and many labor hours, plus the strong possibility of penalties.
You should ALWAYS question unstenciled sheets; even stenciled sheets may be suspect, depending on who is doing the stenciling. Steel mill stenciling is reliable, BUT we now find others in the supply chain applying their own stenciling, and that may or may not be truthful. Test all the steel you buy for coating weight. Handheld testers will give you the coating weight in a range and are usually accurate enough. However, for an exact determination, send a sample to a testing lab.
That is such a cliché, but it certainly applies to buying steel. The buyer indeed must be keenly aware of terms and conditions of the sale and his requirements in both galvanized steel specifications and in the ultimate quantity needed to complete the job.
Many HARDI distributors are providing branches or even individual salespeople with good micrometers and coating weight testers. While sometimes it may be awkward to analyze and test steel in a contractor's facility, more often than not when abuses are uncovered, the contractor is grateful.
Also, insist on mill certifications for the steel that you buy. Others must become involved — particularly contractors and the steel mills. Most mills do not want to support companies that have a reputation for questionable business practices. Hopefully, the current robust steel market will enable some mills to be more selective with their customer base. For many distributors, commercial HVACR contractors represent a large portion of steel sales. Make them aware of the potential confusion in buying and selling steel because ultimately this steel will end up in their possession. We should publicize and educate all pertinent parties about these issues at every level in the channel.
In summary, an unsatisfactory steel purchase results from:
Poor specification at the purchase-order stage.
A lack of understanding of the basics and falling to games/tactics.
A lack of checks and balances (check coil tags, weight, gauge and coatings).
A lack of galvanized coating stamps at the mill level.
Prepared by the Steel Issues Committee of the Heating, Airconditioning & Refrigeration Distributors International, 3455 Mill Run Dr., Suite 820, Columbus, OH 43026 www.hardinet.org.