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Disclaimer — Tube Size vs Nominal Pipe Size

Tube size material is measured by the outside diameter (OD) and wall thickness of the material. Pipe size material is a nominal size and the sizing does not refer to the actual measurement of the material. Pipe size and tube size material are NOT compatible sizes.

Often times people use words like "pipe", "piping", "tube", and "tubing" interchangeably and it can get pretty confusing. Generally, in the automotive industry, pipe is used for building turbo manifolds and tube is used for building intercooler piping and exhaust systems.

  • Tube — Measured by the actual OD
  • Tube — Wall thickness is typically thinner than pipe
  • Tube — Wall thickness is referenced by a gauge or decimal
  • Pipe — Nominal sizing that is not the actual measurement
  • Pipe — Wall thickness is typically thicker than tube
  • Pipe — Wall thickness is referenced by "Schedule"

One of the most common tube sizes used for fabricating an exhaust system is 3-inch diameter. On our site you'll notice that all tube size material is referenced by a decimal size, such as 3.000". We reference tube size material by the a 3-digit decimal size because tube size material is measured by the actual OD of the material3.000" OD tube is 3.000" OD.

One of the most common pipe sizes used for fabricating a turbo manifold is 1-1/2" Schedule 10. The approximate outside diameter (OD) of 1-1/2" pipe size material is 1.900" and the approximate inside diameter (ID) is 1.682". Based on those dimensions it's easy to see that even though the material is referred to as 1-1/2" pipe there isn't a single dimension that is actually 1.500"Due to the nominal sizing of pipe we never list or reference the material on our website as a decimal (e.g., 1.500") like we do with tube size material.

Please be sure to verify that the items in your shopping cart meet the requirements of your project. It is the customer's responsibility to verify the compatibility of the items in their shopping cart. Ace Race Parts is not responsible for orders with mismatched or incompatible products.

For reference, the following chart of standard pipe sizes, ranging from 1/8" NPS to 4" NPS, is provided:

Nominal Pipe Size Chart, Common Turbo Manifold Piping Sizes | Ace Race Parts