Tube Measurement Terms

1) Concentricity - Concentricity implies coincidence of the centers of the OD and ID. However, since a relative displacement (eccentricity) of the centers is difficult to measure directly, while the resulting variation in wall thickness is relatively easy to measure, concentricity and eccentricity are preferably expressed in terms of the latter.

2) Diameter - Average Inside - For all practical purposes, the average ID is the average, at only one cross-section, of the maximum and minimum measured diameters.

3) Diameter - Average Outside - The average OD is the average, at any one cross-section, of the maximum and minimum measured diameters.

4) Diameter - At Any Point - Inside - Inside diameter may be measured at any point around the periphery. Such individual measurements may depart from the nominal due either to the tube being larger than nominal, smaller than nominal, out-of-round, or a possible combination of these.

5) Diameter - At Any Point - Outside - Outside diameter may be measured at any point around the periphery. Such individual measurements may depart from the nominal due either to the tube being larger than nominal, smaller than nominal, out-of-round, or a possible combination of these.

6) Roundness - Roundness implies a truly circular periphery of the inside or the outside surface. The deviation from roundness is measured as the difference between major and minor diameters as determined at any one cross-section of the tube.

7) Wall Thickness - At Any Point - Wall thickness may be measured at any point around the periphery. Such individual measurements may depart from the nominal due to the wall being either thicker than nominal or thinner than nominal, or to the tube being eccentric, or a possible combination of these.

8) Wall Thickness - Average - For all practical purposes, the average wall thickness is the average at any one cross-section, of the maximum and minimum wall thickness.

# Items: 
1
# Items: 
1