Stainless Steel Tubing

Stainless steel tubing is used for many applications that require resistance to high pressures, high temperatures, and corrosive environments.  These include, but are not limited to: petrochemical, gas, nuclear, food and beverage, and chemical plants.  Various wall thicknesses are available to suit a range of pressure requirements, and several different finishes are available to achieve the desired aesthetic.

MSI is a tubing distributor, offering tubing in carbon, stainless, along with several special alloys. With tubing diameters ranging from 1/8” to 2"", MSI can provide the tubing required for virturally any project.

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Tubing Inventory

MSI Supply can often provide the stainless steel tubing listed below for same-day delivery.  MSI’s inventory is largely seamless, but welded is also available upon request.  Large quantities, diameters larger than 2”, and special alloys (Alloy 20, Monel, Hastelloy, Inconel, Titanium, etc.) may be subject to a longer lead time for delivery.

Size Range: 1/16" - 6" Diameter
Thickness: 0.010" - 1.250" (A269 & A511)
Materials: 316/L, 304/L, 317/L, Alloy 20, Alloy 400, Alloy 625, Alloy 825, Alloy C276, Super Duplex 2507
Construction: Seamless, Welded
Finshes: Bright Annealed, Polished, Mill

 

TUBING ORDERING INFORMATION

There are some need-to-know details when ordering stainless steel tubing, such as diameter, wall thickness, material, and construction (seamless or welded).

STAINLESS STEEL TUBING TYPE

There are 2 different types of stainless steel tubing: straight length and continuous coiled stainless steel tubing. The straight length stainless steel tubing typically comes in 20-foot section, but special lengths such as 30 or 40 feet are available upon request.

TUBING DIAMETER & WALL THICKNESS

The primary distinguishing element between stainless pipe and stainless steel tubing is the dimensions to which they are formed.  While pipe follows Nominal Pipe Sizes (NPS) and pipe schedules, stainless steel tubing has exact dimensions.  For instance, a ½” pipe has an outside diameter of 0.840", regardless of the wall thickness (schedule).  A ½” tube, on the other hand, has an outside diameter of ½”, regardless of the wall thickness.  

The tubing burst chart will determine that right wall thickness based on your working pressure. For instance, if you need 1/4” stainless steel tubing suitable to hold a working pressure of 8000psi you will need to use .065 wall thickness. The tubing burst chart shows a bursting pressure of 39,000 psi then you divide this by the factory safety of 4 giving you a result of 9,750 psi which is the maximum allowable working pressure.  The diagram below shows the dimensions of a 1/4" X .065" tube, where the outside diameter is 1/4" and the wall thickness is .065".   Unlike pipe, which has nominal outside diameter sizes, stainless steel tubing outside diameters are exact.  Also, in contrast to pipe, which specifies wall thickness via pipe schedule, stainless steel tubing wall thickness is specified in inches.

stainless tubing wall thickness and diameter diagram

TUBING MATERIAL

The material of the stainless steel tubing will be selected depending on the application and the media that will run across the stainless steel tubing. Some of the most commonly used alloys are 316/L, 304/L, 317L, 2507, Alloy 20, Alloy 400, Alloy 625, Alloy 825, Alloy C276.

STAINLESS STEEL TUBING CONSTRUCTION

Seamless stainless steel tubing is made by extruding and drawing from a billet, producing a very high quality and continuous-steel tube.  Welded, on the other hand, is made from a strip that is rolled and welded to produce a tube. Welded tube is considerably less expensive than seamless stainless steel tubing, but it also provides lower performance.  The working pressure of welded tube is approximately 20% less than that of a like-sized seamless stainless steel tubing.  This, however, is only one disadvantage of welded stainless steel tubing. The weld line for a welded tube is generally less corrosion resistant.  In short, the weld leaves great variability in the final product, and therefore, seamless stainless steel tubing is largely preferred for critical applications. 

STAINLESS STEEL TUBING SURFACE FINISH

There are 3 surface finishes that are well known in the industry: Bright Annealed, Polished and Annealed and Pickled. The Bright Annealed stainless steel tubing, commonly referred to as BA finish, is cold rolled using highly polished rolls in contact with the steel surface, making it both smooth and bright.  This stainless steel tubing is then polished to 400 grit and offers a more accurate thickness than other available finishes.  This finish is generally regarded as the highest quality finish available.

The Polished stainless steel tubing, commonly referred as to PT finish, is mechanically polished and brushed using abrasive materials that cut the surface of the steel to a slight degree. This polishing is typically done to 240 grit. 

The Annealed and Pickled finish, more commonly referred to as Mill Finish, is the basic supply condition for all stainless steel products. In order to maximize resistance to corrosion mill finishes are acid cleaned (pickled) to remove scale formed during the hot rolling and annealing process.  Mill finish is generally less expensive than polished stainless steel tubing, as it follows the same steps of production as PT, without the additional polishing process.  

stainless steel tubing finishes showing mill, polished, and bright annealed

A213 vs A269 Stainless Steel Tubing

Seamless stainless steel tubing is typically manufactured in conformance to ASTM specification, in this case A213 or A269.   A213 is the standard specification for seamless ferritic and austenitic stainless steel tubing for boiler, superheater, and heat-exchanger stainless steel tubing, and A269 is the standard specification for seamless and welded austenitic stainless steel tubing for general service.  Often times, stainless steel stainless steel tubing will be produced in conformance with both A213 and A269 specification, but the required specification should be specified at the time of order.