Stainless steel tubing is one of the most versatile metal alloy materials used in manufacturing and fabrication. The two common types of tubing are seamless and welded. Deciding between welded vs. seamless tubing primarily depends on the application requirements of the product. In choosing between the two keep in mind that first, the tubing must be compliant with your project specifications and that secondly, it must meet the conditions for which the tubing will ultimately be used.
Though both the words tube and pipe are often used interchangeably, largely because both are hollow-shaped, there are important distinctions between the two when determining welded vs. seamless tubing needs. Tubes are measured by the outside diameter (OD) and wall thickness. A pipe, on the other hand, is measured by its inside diameter (ID). In terms of functionality, tubing is generally used in structural and aesthetic applications whereas piping is used for transporting fluids, liquids, and gases.
Knowing that distinction can also help in determining which tubing is best for a given application, welded or seamless. The method of manufacturing welded and seamless tubing is evident in their names alone. Seamless tubes are as defined – they do not have a welded seam. The tubing is manufactured through an extrusion process where the tube is drawn from a solid stainless steel billet and extruded into a hollow form. The billets are first heated and then formed into oblong circular molds that are hollowed in a piercing mill. While hot, the molds are drawn through a mandrel rod and elongated. The mandrel milling process increases the mold’s length by twenty times to form a seamless tube shape. Tubing is further shaped through pilfering, a cold rolling process, or cold drawing.
A welded stainless steel tube is produced through roll-forming strips or sheets of stainless steel into a tube shape and then welding the seam longitudinally. Welded tubing can be accomplished either by hot-forming and cold-forming processes. Of the two, cold forming results in smoother finishes and tighter tolerances. However, each method creates a durable, strong, steel tube that resists corrosion. The seam can be left beaded or it can be further worked by cold rolling and forging methods. The welded tube can also be drawn similarly to seamless tubing to produce a finer weld seam with better surface finishes and tighter tolerances.
There are benefits and drawbacks in choosing welded vs. seamless tubing.
By definition, seamless tubes are completely homogenous tubes, the properties of which give seamless tubing more strength, superior corrosion resistance, and the ability to withstand higher pressure than welded tubes. This makes them more suitable in critical applications in harsh environments, but it comes with a price.
Benefits
Applications
Welded tubing is generally less expensive than seamless tubing due to the simpler manufacturing process in creating welded tubing. It is also readily available, like seamless tubing, in long continuous lengths. Standard sizes can be produced with similar lead times for both welded and seamless tubing. Seamless tubing costs can be offset in smaller manufacturing runs if less quantity is required. Otherwise, though custom-sized seamless tubing can be produced and delivered more quickly, it is more costly.
Benefits
Applications
Costs of seamless and welded tubing are also related to such properties as strength and durability. Welded tubing’s easier manufacturing process can produce larger diameter tubing with thinner wall sizes for less. Such properties are more difficult to produce in seamless tubing. On the other hand, heavy walls can be achieved more easily with seamless tubing. Seamless tubing is often preferred for heavy wall tubing applications that require or can withstand high pressure or perform in extreme environments.
Several factors combine to make stainless steel tubing an excellent choice for structural applications in industries ranging from automotive and aerospace to medical and marine. If you’re still unsure which tubing is best for your application, as a point of reference, though seamless tubing can be substituted for welded tubing, welded tubing can never be substituted for seamless tubing.
Stainless steel tubes are often used in applications that need the advantages of stainless steel material – low maintenance, corrosion-resistance, and versatility. Tubing can serve many purposes across a variety of industries, with two major types of stainless steel tube: welded and seamless. Here, Atlantic Stainless covers the production process and the main differences between these types of stainless steel tubing.
Raw material begins in the form of hot extruded seamless pipe, which is then cold reduced and processed through tube reducers in a long, straight form. Cold reducing is the most effective manufacturing method for longer lengths of tubing. Rolled pipes are cut to the required lengths and cleaned to remove debris in preparation for heat treatment, which is applied to remove any stresses that could occur during the formation or welding process.
Various heat treatments can be used for tubing manufacturing, particularly annealing – this improves the structure of the metal and makes it more ductile for use in applications.
Welded stainless steel tubing is provided to the manufacturer in coils, which are then processed to improve the finish, remove debris, or for any alterations needed in the end product. Once the initial processing is complete, the coil is run through rollers to form the shape and prepare for welding.
Welded tubing can be either hot or cold-formed, and the finished results will differ depending on how it’s been prepared – for example, cold-formed stainless steel has a smoother finish and closer tolerances than hot-formed stainless steel. That said, regardless of how it was formed, the welding process will remain the same. The steps are as follows:
Seamless stainless steel tubing can be manufactured using a variety of methods, including piercing, gun drilling or extrusion.
Piercing: Uses a metal bar as its base material which is pierced with holes, then heated and rolled into a tube form.
Gun Drilling: This method produces the best quality tubes that typically outperform tubes produced by other means. It requires a round metal bar be inserted into a straight flute drill.
Extrusion: A steel bar is fed into a tube and worked through a die, which is both effective and efficient, although this process requires additional preparation than the other two tubing methods.
In some cases, cold forming can be utilized if the tubing has a more rare composition or unique dimensions – these methods include cold drawing and cold pilgering.
Cold Drawing: Involves using a die to alter the tube’s overall shape.
Cold Pilgering: Reduces the wall thickness of the tubing or piping.
Both of these cold forming processes typically aren’t necessary when manufacturing steel tubing, but when and if required by specific applications, are the preferred standard cold forming methods.
As aforementioned, there are numerous benefits to using stainless steel for your applications. The material’s extreme versatility and resistance to corrosion is hard to match, which is why there are so many industries utilizing it, including but not limited to:
Atlantic Stainless is a renowned distributor of stainless steel tube, bar, sheet, plate, pipe, beam, channel, and hardware. As stainless steel suppliers, we proudly offer a huge variety of high-quality products and unmatched expertise in our services.
Want to see what products we have available? Browse our catalog, search for a product, or contact us online today for help with your order.
The company is the world’s best how to mud metal corner bead, wholesale using fiberglass drywall tape, Fiberglass Mesh Drywall Tape supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.