Welded and seamless stainless steel pipes

Stainless steel pipe is one of the most widely used metal alloy materials. Two common types of oil pipe are seamless pipe and welded pipe. The choice between welded oil pipe and seamless oil pipe mainly depends on the application requirements of the product. When choosing between the two, remember that first, the tubing must meet your project specifications, and second, it must meet the conditions in which the tubing will ultimately be used.

Seamless oil pipe manufacturing

Knowing this difference can also help determine which pipe material is best for a specific application, welded or seamless. The methods of manufacturing welded and seamless oil pipe are obvious from their names alone. Seamless pipes are by definition -- they have no welds. Tubes are manufactured through an extrusion process where the tube is drawn from a solid stainless steel billet and extruded into a hollow shape. The billet is first heated and then formed into a rectangular round mold, which is hollowed out in a punching machine. While hot, the mold stretches and elongates through the mandrel. The mandrel milling process increases the mold length by 20 times, forming a seamless tube shape. The tubing is further formed through the Hajj, cold rolling process, or cold drawing.

Welded pipe manufacturing

Welded stainless steel pipe is produced by rolling stainless steel strips or sheets into a tube shape and then welding the seams longitudinally. Welded oil pipes can be completed by two processes: hot forming and cold forming. Of the two methods, cold forming results in a smoother finish and tighter tolerances. However, each method produces durable, strong, corrosion-resistant steel pipe. Welds can be beaded or further processed using cold rolling and forging methods. Welded pipe can also be stretched like seamless pipe to produce a better weld with a better surface finish and tighter tolerances.

The choice between welded and seamless

There are advantages and disadvantages to choosing between welded oil pipes and seamless oil pipes.

Seamless oil pipe

By definition, seamless pipes are completely uniform pipes with characteristics that give seamless pipes greater strength, better corrosion resistance, and the ability to withstand higher pressures than welded pipes. This makes them more suitable for critical applications in harsh environments, but it comes at a cost.

benefit

stronger

Excellent corrosion resistance

Higher pressure resistance

app

Oil and gas control line

chemical injection line

Undersea safety valve

Chemical process plant steam and heat trace beams

Fluid and gas transfer

Welded oil pipe

Welded oil pipe is generally less expensive than seamless oil pipe because the process of making welded oil pipe is simpler. It's also easily available, like seamless tubing, in long continuous lengths. Standard sizes of welded tubing and seamless tubing can be produced with similar lead times. The cost of seamless tubing can be offset in smaller production runs if lower quantities are required. Otherwise, while custom-sized seamless pipes can be produced and delivered faster, they cost more.

benefit

Cost effective

Very long ready to use

Fast delivery time

app

Building applications

hypodermic needle

auto industry

Food and Beverage Industry

Marine industry

Pharmaceutical Industry

Welding costs vs. seamless costs

The cost of seamless and welded pipes is also related to properties such as strength and durability. The easier manufacturing process of welded oil pipe can produce oil pipe with larger diameters and thinner wall dimensions at lower costs. This kind of performance is more difficult to produce in seamless tubing. On the other hand, thick walls can be achieved more easily with seamless tubing. Seamless tubing is often preferred for thick-wall tubing applications that require or are able to withstand high pressures or operate in extreme environments.

Overall, many factors combine to make stainless steel pipe an excellent choice for structural applications in industries ranging from automotive and aerospace to medical and marine.

PS: The article is excerpted from Eagle Stainless Steel Pipe & Manufacturing