ASTM TUBING MATERIALS
The table shows the most common ASTM tubing materials, by type (seamless and welded) and material group (carbon/alloy and stainless/nickel alloys). Tubes are used to manufacture boilers, heaters, and superheaters. To learn about the dimensions of tubing, refer to this article (ASTM A450).
COMMON ASTM MATERIALS FOR TUBING
|TYPE||CARBON STEEL / ALLOY STEEL
ASTM MATERIALS FOR TUBES
|STAINLESS STEEL / NICKEL ALLOY
ASTM MATERIALS FOR TUBES
seamless carbon/alloy tubes
|ASTM A213/A269 (smls stainless steel tubes)
ASTM A789 (smls duplex, superduplex tubes)
ASTM B338 (smls titanium tubes)
ASTM A179/A334 carbon steel welded tubes
|ASTM A249/A269 (welded stainless steel tubes)
ASTM A789 (welded duplex, super duplex tubes)
ASTM B468 (welded Alloy 20 tubes)
ASTM B515/B516/B704 (welded Inconel, Incoloy tubes)
ASTM B622/B626 (welded Hastelloy tubes)
ASTM B674 (welded 6Mo tubes)
TUBING MATERIALS SELECTION
When selecting tubing, one of the biggest issues after the definition of the sizes (outside diameter and wall thickness) is the type of material to use. We list the main types of tubing materials and their features.
CARBON STEEL TUBING
Fundamentally, carbon steel consists of iron and carbon. Carbon steel is the commercial type of alloy as the most commonly used form of steel. The carbon content can be both a blessing and a curse when it comes to commercial steel (an increase in the carbon content, while enhances the hardness and strength, also determines an increase of the brittleness and decreases the weldability).
Carbon steel will most likely be categorized based on manufacturing process (cold drawing and hot finishing). Cold drawing refers to a method in which the tubing is drawn and shaped at room temperature. This method is beneficial when a good surface finish is required, as well as closer tolerances, and is common for tubing with tiny walls thickness or smaller diameters; hot finishing means that the tube is manufactured by forming the tube by using high temperatures:
- Boiler, oil, and gas steel tubing: manufactured by cold drawing or hot finishing.
- 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: This type of tubing is found 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 is common for 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.
STAINLESS STEEL TUBING
Unlike carbon steel, stainless steel is easy to spot, as its chromium content makes it shine. This material does not readily corrode, rust or stain with water as, instead, ordinary steel does. However, the word “stainless” may be misleading, as stainless steel is not fully staining proof, most notably under low-oxygen, high-salinity or poorly circulated environments.
The two most common grades for SS tubing are:
- 304 Stainless Steel: This is the most versatile and widely used stainless steel. SS304 is impressively resistant to oxidation and corrosion while providing great durability. This material provides easy fabrication and cleaning with the ability to prevent product contamination.
- 316 Stainless Steel: SS316 is a heat-resisting steel with superior corrosion resistance as compared to other chromium-nickel steels. This material is resistant to chemical corrodents such as seawater 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.
Copper tubing is a strong long-lasting permanent choice for leak-proof systems. Copper tubing is incredibly resistant to 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 wall thickness of the tube:
- 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. 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.