Let’s talk about carbon steel pipe. Steel is an alloy. An alloy is a mixture of at least two elements, one of which must be metallic. In its simplest form, steel is two elements mixed together: iron and carbon. Though carbon is the main alloying material for iron, some other elements like tungsten, chromium, manganese can also be used for the purpose. This is called “carbon steel.” The more carbon there is contained in the steel, the stronger it gets when heated. This makes the steel become less ductile. Carbon steel pipe, then, is a steel alloy that contains carbon ranging from 0.12% all the way to 2%. The percentage of alloy in carbon steel affects weldability, the hardening process, and resistance to corrosion.
Carbon pipes are widely used in a number of different industries because of a couple main reasons:
There are three broad categories of carbon steel: high carbon steel, medium carbon steel, and low carbon steel. The content of carbon contained in these varieties of steel determines the use in the manufacturing processes. High carbon steel has the most carbon content at 0.60%-0.99% and it is the hardest carbon steel. High carbon steel has much better tensile strength so it is commonly used to make cutting tools, blades, punches, dies, springs, and high-strength wire. Medium carbon content is at 0.30%-0.59%. Medium carbon steel is easier to machine, adding silicon and manganese improves the overall quality of the carbon. It is commonly used structurally in buildings, bridges, axles, gears, rails, shafts, cars, refrigerators, washing machines, and pipelines. Low carbon steel has the least amount of carbon at 0.16%-0.29% and is the softest carbon steel. Low carbon steel is made into flat-rolled sheets and strips, which is then used for shipbuilding, wire, vehicle bodies, and domestic appliances. It is also used for fencing, gates, and railings because it is hard but not too brittle. There is also ultra carbon steel which tends to be less brittle and very hard. This is used to make extremely hard components like blades, cutting tools, large machine parts, hot water radiators, industrial castings, and metal lamp posts. Ultra carbon steel is also called “cast iron” which is also used to make cooking pots.
Carbon steel piping has one major drawback, iron oxide (aka rust). The iron in the steel chemically reacts with atmospheric oxygen and creates iron oxide. Iron oxide, or rust, is what causes corrosion. Iron oxide weakens the steel. If left untreated, the pipe will ultimately fail. Corrosion of carbon steel usually happens when the relative humidity of the air is 70% to 80% and the air temperature is above 32F. To prevent corrosion of the steel, the pipes are often coated with a type of rust inhibitor. That could be black mill lacquer, varnish, fusion bonded epoxy, water-based rust inhibitor, or other various treatments. Rarely will you see bare steel pipe.
Which Type of Carbon Steel Piping is Best?
One is not better than the others. It just depends on your application and your budget for the steel. There are different specs and grades for carbon steel compared to other steel that has different properties. To figure out what steel is best for you and your needs, an engineer will be able to help you decide.
Whether you are looking to purchase or sell carbon steel pipe, Bryzos® Steel Marketplace can put clients in contact with each other. The Bryzos® negotiating tool, the Bid Blaster, can put buyers and sellers in contact to meet the needs of all steel.