Corrosion is often considered the greatest threat to the durability of corrugated steel pipes. For this reason, manufacturers of corrugated steel pipes often go to great lengths to ensure that their products are highly-resistant to corrosion.
In a large number of cases, manufacturers protect their products from corrosion through a process known as hot-dip galvanization. This article provides answers to three questions about hot-dip galvanization. Those training to become manufacturing engineers should find this introduction useful.
How Does Hot-Dip Galvanization Work?
The process is relatively simple (at least in theory). Pipe manufacturers will melt sufficient quantities of zinc metal so as to create a "zinc-bath" of sorts. Corrugated steel pipes are then submerged into the zinc-bath and they're left in that state the pipes are fully coated with zinc.
Exposure of the "zinc-bath" to the atmosphere prompts two chemical reactions. The first of these reactions is that between the molten zinc and oxygen in the atmosphere, which results in the formation of zinc oxide. The second reaction is that between zinc oxide and carbon dioxide in the atmosphere. This leads to the formation of zinc carbonate. Zinc carbonate on the surface of corrugated metal pipes acts as a protective layer that prevents corrosion.
How Does Pipe Contamination Affect The Results Of The Process?
The effectiveness of this process (hot-dip galvanization) can be affected by a number of factors. Contamination of corrugated steel pipes is perhaps the most common of these factors. The steel surfaces of a corrugated pipe are considered to be contaminated when they have impurities such as oil and grease.
The presence of impurities on corrugated steel pipes may interfere with the occurrence of the two chemical reactions mentioned above, thereby affecting the quality of zinc coatings formed on the pipe. Severe contamination on steel pipes may prevent the occurrence of the two reactions, thereby preventing the formation of zinc coatings in the pipe.
For this reason, fabrication specialists are often advised to undertake a thorough cleaning of corrugated steel pipes before the galvanization process.
How Does The Zinc Coating Protect Against Corrosion?
The zinc coating on corrugated steel pipes offers two types of protection against corrosion. Cathodic protection is the first of these. Because zinc is anodic, it serves as the "sacrificial anode" in the event that a corrosion cell is formed on the structure of corrugated steel pipes.
Barrier protection is the second type if protection. Thanks to its dense nature, zinc metal acts as a protective barrier that prevents the penetration of electrolytes and/or moisture into the steel surface of the galvanized corrugated pipe. For more information, contact a company like Corrugated Metal Pipe Manufacturing PTY LTD.