What do these phrases mean?

Obtaining suitable products for your projects isn’t easy. That is unless you know where to look. We are the number one ERW steel tube supplier West Midlands has. In our collection, you can find designs that we’ve cut to various lengths, as well as different shapes of tubing. With such a varied range, we can meet a host of customer requirements.

Some people are often left baffled by the technical specifications and phrases we use in the tubing industry. We want to change all of that. In order to do so, we’ve created a little guide that provides definitions for some of these terms. This should clear up any confusion you have.


Firstly, we will cover eccentricity. Eccentric tubes have an outer and inner diameter with different centre points. As a result the circles are not concentric. You can check for this by looking at the tube’s wall thickness at the desired cross section to form minimum and maximum. The eccentricity at this cross section would be a half the variation between the maximum and minimum wall thicknesses.


Next, we’ll discuss ovality tolerance. You acquire the variance between minimum and maximum OD dimensions, or out-of-roundness, by cautiously calculating the low and high points of any tube section. Inside, the minimum and maximum OD dimensions need to fall.

Average OD

Finally, we have the average OD. This is the average of at least four micrometer recordings. This includes the low and high points.

At Union Steel Tubes, we are ISO 9001 approved and possess the equipment to take on any job we’re given. We make sure that every tube is available and ready for a quick delivery once an order comes in. Therefore we are the most reliable ERW steel tube supplier West Midlands has to offer.

If our company interests you and you’d like more information, feel free to contact us anytime. In addition you can download our product list via our website. Please note that we can offer other sizes as well as those ones listed.