What is galvanized coating?

December 1, 2010

Galvanized coating is a type of sealant to protect a pipe support against corrosion. It has two advantages over a zinc coating. During galvanizing, the molten zinc reacts with the carbon steel to form layers of zinc/iron alloys. The alloy layers between have increased hardness to provide mechanical (barrier) protection and because of their zinc content they are also anodic relative to carbon steel. The hardness of these alloy layers provides much more protection from scratches than paint can provide. This is important for most pipe supports applications.

Constant Spring Assemblies With Galvanized Coating
Constant Spring Assemblies with Galvanized Coating

Valuable Ideas Come From Customers

August 17, 1996

One of the “success stories” of Houston businesses during 1996 is Continental Airlines. In their March 1996 magazine Chairman Gordon Bethune credited Continental’s customers in an article titled Thanks for your Ideas. This article struck a cord with our President, Durga Agrawal, and we began to review the many ideas for improvement at Piping Technology that came from our customers. Here are some examples of ideas for improvements which help make us so competitive.

The most recent suggestion came from an engineer at Tippet & Gee for an improvement to figures 700 through 1200, pipe shoes with slide plates. If the web is cut so that the center of the web is taken up to the surface of the pipe, any bending movement produced by overloading which might cause deflection to the slide plate will be prevented. This is a simple but elegant solution which is inexpensive to fabricate.

Some improvements to our constants suggested by customers include: a full size travel scale which allows field engineers to observe actual movement of supported pipes in the field (Bechtel engineer working with Houston Lighting & Power); addition of scales for field adjustment of loads (HL&P engineer); the use of DU bearings to hold stainless steel pins eliminating any failure of this component during the life of the constant and eliminating any need of lubrication of the bearing (Brown & Root engineer).

For many years the fine companies who provide us with galvanizing services have experienced problems with the many small pieces we send to them. (They get lost in the bottom of the vats required for large structural steel.) A customer suggested we combine small parts in some way. This lead to the idea of drilling holes and wiring many small pieces together. While adding some cost to the process, this has significantly reduced the number of parts “lost at the galvanizer” and has improved our ability to deliver on time. Like Continental, we here at PT&P say, “Thanks for your ideas!”

Corrosion Problems? Fight Back with Hot Dip Galvanizing

August 21, 1995

Many piping groups in E&C firms are reviewing their strategies for combating corrosion in piping components. The history of Piping Technology & Products, Inc. has been strongly influenced by industry efforts to combat corrosion, which has always been a major problem at Gulf Coast U.S.A. petrochemical plants. The bolted design we developed for variable springs was originally justified as a quality improvement for hot dipped galvanized finish. This approach allows the spring to be assembled and calibrated with no welding after galvanizing. Prior to this PT&P innovation, the heat from welding could damage both the finish of the welded component and the neoprene coating of the spring coil inside the can. The thousands of springs we have supplied with hot dipped galvanized finish and neoprene-coated coils have proven the validity of this approach as the most cost-effective way to prevent corrosion.

Hot dip galvanizing is a unique process which develops a metallurgical bond of zinc-iron alloy between the zinc coating and the steel product it protects. It provides a continuous layer barrier which physically isolates the steel from the environment. Painting, on the other hand, is a barrier coating which is subject to damage from contact (scratching). Hot dip galvanizing provides a much longer life than painting in corrosive environments partly because zinc forms protective oxide and carbonate films which reduce the rate of corrosion dramatically. Steel exposed to the same environment will corrode at a rate of about twenty-five times the rate of zinc. Zinc also resists accelerated local corrosion even when its outer film has been broken or scratched. The actual rate varies with the electrolyte at the surface.

We provide various types of finishes for corrosion. Contact us for the right finish for your application.


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