Choosing the Right Tubing Material – When selecting tubing for your application one of the biggest factors beyond size is the type of material you may need. Tubing is necessary in both complex and basic machinery for all types of applications to function. Today, we will take a deeper look into some of the most popular materials for tubing: carbon steel, stainless steel and copper materials.
The first thing to tackle is one of the biggest questions when discussing tubing. What classifies a tube as a tube? Well, the primary difference between tubing and pipe is wall thickness plus the resulting joining method. Generally, tubing is considered thin-walled material. However, there are a number of other differences between pipes and tubing. Once you have classified your need for tubing or piping, it’s time to dive into which material you will need.
Tubing Material – Carbon Steel Tubing
Fundamentally, carbon steel is a steel alloy that consists of iron and carbon. Carbon is the most important commercial steel alloy as it is the most commonly used form of steel in the United States. About 85% of all steel used is carbon steel. For all the beginners out there, carbon content can be both a blessing and a curse when it comes to commercial steel. When you increase the carbon content in your tubing, it increases hardness and strength. However, more carbon also means increased brittleness and less ease with welding. Carbon steel tubing is most commonly used in building applications that involve the flow of gas, fuel or any type of liquid.
Carbon steel will most likely be categorized based upon the way it was originally manufactured. The two methods are cold drawing and hot finishing. Cold drawing refers to a tube-building method in which the tubing is drawn or shaped at room temperature. This method is beneficial when you need a better surface finish, closer tolerances, lighter walls or smaller diameters of tubing. The hot finishing method is when tubing is built while the material is extremely hot. Carbon steel tubing comes in several major types, usually designed with a certain application in mind.
Boiler, Oil and Gas Steel Tubing: This type of tubing can be created using either cold drawing or hot finishing. Its sizing will depend on the way in which it was constructed.
Hot Finished Seamless Tubing: This tubing has a completely smooth surface and can be used in an array of applications including construction, agriculture, industrial equipment, machinery, mining, energy, drilling and transportation.
Single-Wall Carbon Steel Tubing: You will find this type of tubing in low-pressure applications in the automotive industry. It can be used for fuel and vacuum lines, fuel rails, power, steering and engine oil coolers. This type of tubing can also be either cold drawn or hot finished.
Double-Wall Carbon Steel Tubing: This type of tubing will be found in high pressure applications such as hydraulic or pneumatic applications. Available in a wide variety of sizes, this type of tubing can also be found with a range of different coatings and materials including (but not limited to) phosphate, zinc dichromate and chromium free.
Tubing Material – Stainless Steel Tubing
Unlike carbon steel, stainless steel is easy to recognize because of the shine it emits due to its chromium content. As a material, stainless steel is quite impressive. This material does not readily corrode, rust or stain with water as ordinary steel does. However, “stainless” may be a bit misleading, as stainless steel is not fully stain proof, most notably under low-oxygen, high-salinity or poorly circulated environments.
In regards to tubing, there are most likely two general types of stainless steel you will come across in your search: 304 and 316 stainless steel.
304 Stainless Steel: This is the most versatile and widely used stainless steel. 304 stainless steel is impressively resistant to oxidation and corrosion all while providing great durability. This material provides easy fabrication and cleaning with the ability to prevent product contamination.
316 Stainless Steel: The 316 stainless steel is a heat-resisting steel with superior corrosion resistance as compared to other chromium-nickel steels. This material is especially resistant against chemical corrodants such as sea water and brine solutions and considerably more resistant to solutions of sulfuric acid, chlorides, bromides, iodides, fatty acids and high temperatures. 316 stainless steel is durable, easy to fabricate, clean, weld and finish.
Tubing Material – Copper Tubing
Copper tubing is a strong long-lasting permanent choice for a leak proof system. Due to the permanent nature of copper tubing, you must be sure that you have a skilled technician during installation. Copper tubing is incredibly resistant against corrosion and can be joined by using flare connection, compression connection or solder. The two basic types of copper tubing are soft (annealed) copper and rigid (hard drawn) copper. Both are further classified according to the thickness of the tubing wall.
Annealed Copper: This type of tubing is tough and frequently found in specialty applications such as distilling or appliances. Due to the fact that soft copper can be easily bent, it must be supported with clamps or brackets every four to six feet. This type of tubing has the tendency to harden as a result of vibration, oxidation and bending. When this happens, copper will crack at stress points especially if there are flared or formed tubing ends. To remedy this, re-soften the tubing by heating it to a bright red surface color.
Hard Drawn Copper: Rigid copper tubing is more commonly found and is probably used to channel water through your home. This type of tubing cannot be bent easily so soldered and brazed fittings are used when making connections or changing directions. Due to its stiffness, hard-drawn copper requires fewer supports or brackets than soft copper tubing, making assembly much quicker.