ERW vs SML – Which is best?

ERW tubesWhen it comes to tubing, one of the most difficult decisions is whether to opt for ERW tubes or SML. The first are resistance welded, beginning life as a strip of metal. The latter are seamless and perforated. They tend to begin life as solid bars. Both options are great for different reasons. You should select the best one for your application.

At Union Steel Tubes we stock both types but specialise in ERW. This is because it is suitable for more uses and is generally the most cost effective option. There are also a number of reasons why it is better than SML.

Quality of the blank tubes

The steel in ERW tubes is generally very high quality. It can be treated in a number of ways to reduce various elements within the alloys. As a result this can improve strength, toughness, and weld performance. SML steel on the other hand may be less pure and have more carbon in the alloy. Therefore it may not be as tough.


Because ERW tube begins as strips of steel, it is much easier to control the wall thickness of the tubing. It should remain relatively consistent around the entire circumference. There is also far more range in terms of the thickness of the walls. SML tubing on the other hand has limits; it is only possible to perforate the bar a certain amount so it can be challenging to have thinner walls.

Grain and microstructure

ERW tubes can also have fantastic grain size and microstructure density. This can offer great aesthetics as well as excellent performance. Sadly SML tubes cannot hit the same high standards.


The area where SML tubing really excels over ERW is in leak resistance. There is no risk of this occurring at any point along the length of the tube. This is because the there is no break in the circumference. Unfortunately, no matter how good welded tubing is, there will always be a seam at some point. Even if the welding is high quality, in time leaks could occur along this line.

The highest quality ERW tubes

If you need tubing for any kind of project, Union Steel Tubes can supply it. We produce it at our mill and have quality controls in place to ensure it is consistent. We offer a wide range of sizes in terms of ID, OD and wall thickness. On top of that we can offer various lengths and cut tube to size in-house.

Contact us today if you want to order ERW tubes. We have a wonderful reputation and support clients in various industries.