We get many questions daily about the size of "pipe" as compared to "tube", for anyone not familiar with the differences this can become very confusing. Many people refer to all round, hollow metals as "pipe", when in fact "pipe" and "tube" are two completely different products and as industry standards go, the fittings and sizes are completely different.

Here is a brief explanation of the two.

PIPE

Pipe was originally produced to carry liquids inside the pipe and was therefore sized according to the interior capacity. This standard allowed engineers to calculate the amount of volume the pipe could transfer when designing projects.

As such, listed pipe sizes are identified by "Nominal Pipe Size (NPS)" and are generally closer to the inside diameter (ID) of the pipe and have little or no resemblance to the outside diameter (OD).

The wall thickness (W) of the pipe is listed as a "schedule". The larger the number of the " Schedule" the thicker the pipe wall is. However as the pipe size increases, so does the thickness of each schedule. As such, a Schedule 40 pipe in 1 inch NPS, has a thinner all than a Schedule 40 pipe in 3 inch NPS.

TUBE

Tubing sizes are listed as "Outside Diameter (OD) and Wall Thickness (W). Listed sizes of tubes are exact, a 1 inch "tube" will measure 1 inch on the OD. The "Inside Diameter" (ID) will become smaller as the wall thickness increases.

To find the "Inside Diameter" (ID) of any tube, simply subtract the wall thickness(x2) from the "Outside Diameter" (OD) of the tube.

Stainless Steel Sheet Finishes

Stainless steel sheet is produced in many types of finishes due to the various uses and applications that stainless steel can be used in. It has become popular in kitchens due to its low maintenance, cleanliness, appearance, and corrosion resistance to food acids and water.

For example, the most commonly used finish for most stainless steel appliances is the No. 4 "Brushed" finishes. This finish provides a nice bright, brushed appearance that will withstand daily use and mask the fingerprints, scuffs, scratches, etc.

2B (Bright, Cold Rolled)

A bright, cold-rolled finish is the most commonly "Mill" finish for light gauge stainless steel sheet. It resembles a very hazy mirror, with some reflection evident. It is obtained by a final light roll pass of the sheet through polished rolls. This is the general-purpose cold-rolled finish that can be used as is, or a preliminary step to polishing. 2B sheets do not typically have any protective coating and therefore may contain light marks from handling and shearing operations.

No. 3 (Brushed, 120 Grit)

An intermediate polished surface obtained by finishing with a 120-grit abrasive. A directional course "grain" running in one direction. Used in heavy use areas or can be further polished after fabrication. Our #3 polish stainless sheets come with peel off protective covering on one side that can be removed after the material is installed.

No. 4 (Brushed, 150 Grit)

A polished surface obtained by finishing with a 150 mesh abrasive. This is a general purpose bright finish with a       visible directional “grain” which prevents mirror reflection. Commonly found in kitchen applications. We stock a variety of sizes and gauges in the #4 polished stainless steel sheet. Like the #3 finish, these sheets also come with a peel off protective coating on one side.

No. 8 (Mirror)

The most reflective surface of stainless steel commonly available, It is produced by polishing with successively finer abrasives and buffing extensively until all grit lines from preliminary grinding operations are removed. It is used for cosmetic applications such as mirrors and reflectors.

BA (Bright Annealed)

Sometimes confused with the No. 8 finish, although it is not as "clear and defect free" as the No. 8 mirror finish. This is obtained by annealing the material under an atmosphere so that scale is not produced on the surface. This results in a highly reflective, mirror-like finish, without further polishing.

One of the most common differences in the way most other metal flat bars and Stainless Steel Flat Bar are produced is that sheared plate is often "edge treated" and sold as flat bar and "True" Flat Bar. which is produced to size.

HRAP (Hot Rolled, Annealed and Pickled) is produced at the mill to the specific size indicated. The finish on all four sides is virtually identical. The corners are relatively square, and the tolerances are reasonably close to the actual dimension listed – usually within just a few thousandths of an inch. Also known as "True Flat Bar".

SHEARED AND EDGED is bar cut and processed from stainless plate. The edges are milled and have a slightly different finish from the flat sides. Though it is flattened and straightened as part of the process, sheared and edged bar is not as dimensional “true” as true flat bar. Still, it remains an extremely viable and much less expensive alternative to true flat bar.

Finishes: There are a couple of standard finishes available today, HRAP and Cold Finished (aka Cold Drawn).

HRAP: Hot Rolled, Annealed, and Pickled (aka "MILL" Finish) has a dull gray, rough finish that comes as it was produced and it mostly dimensional larger than listed sizes.

COLD FINISHED: A shinier finish, with sharp edges and dimensional closer to listed size. This finish is most commonly produced in the 303 alloy.

There are two standard types of aluminum angle most commonly produced today, Architectural and Structural.

Structural Aluminum Angle

The "Structural" aluminum angle has rounded inside corners and is most commonly produced in the 6061-T6 aluminum alloy, This type of angle is commonly used for (as the name suggest) structural applications where lightweight, yet high strength material is required. The 6061 aluminum alloy offers good corrosion resistance, easily formed, welded, and drilled,

      Architectural Angle

The "Architectural" aluminum angle has square corners on both the inside and outside of the angle. It is commonly produced in the 6063 aluminum alloy and usually in lighter gauges and sizes than the structural angle. The 6063 alloy is corrosion resistant and provides a better surface finish. Typical uses include light structural and cosmetic uses. The 6063 alloy is more difficult to machine than the 6061 alloy, but can be welded, formed and polished.

Sizes are listed as: Alloy- Temper - Type of Angle - Leg Length (1) x Leg Length (2) x Total Length (Thickness)

                Example: 6061-T6 Structural Aluminum Angle 1" x 1" x 36" (1/8")

Online Metal Supply stocks a variety of sizes and alloys in both types of aluminum angle, Check out our Aluminum Angle to see what alloys and sizes we currently have in stock.