Gauge to Inch Equivalents
(tubing material thickness)

All tubing wall thickness is measured by in gauges. Gauges range from 0000 GA. TO 36 GA., with the most common sizes used in pneumatic conveying being 11, 14, and 16 GA. 11 GA seems to be the most favored of the three.

When the gauge size increases or decreases, the outside diameter (OD) always stays the same while the inside diameter is changing. (For example, 4" 11 GA, 14GA and 16GA tubing all have 4" OD's but have different ID's).

As the gauge increases, the wall thickness gets thinner.

Pipe Weights & Dimensions

All pipe wall thickness is measured in schedules. Schedules range from 5 to 160, with the most common sizes used in pneumatic conveying being SCH10, SCH40 and SCH80. SCH40 seems to be the most used of the three.

When the schedule size increases, the wall thickness gets thicker.

When discussing 3" pipe, 4" pipe, 5" pipe or any other sizes, we are referring to the ID of the pipe, not the OD as in tubing. The most important thing to remember is that only SCH40 pipe has the same ID as it's nominal size.

For example, 4" SCH40 pipe has a 4" ID while 4" SCH80 pipe has a 3.75" ID because its wall thickness is greater. 4" SCH10 on the other hand has a 4.25" ID because its wall thickness is thinner.

Another example, 3" SCH40 pipe has a 3" ID while 3" SCH80 has a 2.75" ID, 3" SCH10 has a 3.25 ID because the wall thickness varies.

The thickness gets even thicker as the diameters get larger. Note that SCH40 is used as the standard when discussing pipe thickness.

The OD's remain the same while the ID's change even though we are still speaking in terms of ID's.