Difference between Seamless and Welded Pipe


What Is The Difference Between Seamless And Welded Pipe?
In contrast to welded pipes, which are joined end to end from a sheet, plate, strip, or coil of the same material, seamless pipes are drawn from a single billet of material. Ferritic, austenitic, duplex, and other high alloy alloys can be used as the materials. In terms of dimensions, seamless pipes are more precise than welded tubes. For seamless tubes and pipes, the wall thicknesses are uniform, and the overall roughness is lower. The absolute roughness of welded pipes is higher than that of seamless pipes because they have seams or joints.

Price Difference Between Seamless And Welded Pipe

Prices for seamless pipe and welded pipe can differ depending on whether the production is fully worked or as welded. In comparison to as welded and seamless pipes, fully welded pipes are more expensive. Sometimes the substance makes welding difficult. The cost of welded pipes is higher than that of seamless pipes when welding heavy alloys, which require special techniques. The drawing process is more expensive than welding if the material is simple to weld, like the 304 and 316 alloys.

Also, these materials do not require preheating for welding. So the seamless pipes are expensive in such material grades than the welded pipes. The preheating and post weld heat treatment requirements can also make the price difference between the seamless and welded pipe types.

Seamless And Welded Pipe Manufacturing Process

It's possible to cold draw the seamless pipes. This means that these pipes are made at room temperature from a single billet of material. Additionally, the lack of heating lessens the material's expansion and distortion. As a result, the dimensions can be precise. Plates, strips, and sheets are used to weld the pipes. These sheets or strips are bent and joined end to end by welding. The heat produced during welding may result in minor distortions in the pipe's dimensions.

SSome materials need to be heated up first before welding. For some material grades, post-weld heat treatments are also necessary to guarantee that the welded connections are adequately bonded. At any given place, seamless tubes and pipes are equally strong. However, the welded connections on the tubes and pipes can be fragile. As a result, the seamless pipes nevertheless maintain the material's minimal yield and tensile strengths. The maximum strength is constrained by the strength at the welded joints, thus the strength values are slightly lower for the welded pipes.

Seamless And Welded Pipe Application

The uses for seamless pipes are rather specific. Seamless pipes are preferred for applications including tools, equipment, sensitive measuring devices, high-temperature, high-pressure units, medical equipment, hydraulic applications, power plants, nuclear power plants, chemical applications, and pharmaceutical applications. The majority of industrial applications can use welded pipes and tubes without requiring consistent strength or exact dimensioning.

Water lines, water purification, sea water, marine, building, petroleum, oil and gas, heat exchangers, and other applications are only a few examples. It should be noted that depending on the application's need for accuracy and uniform strength, both seamless and welded pipes could be employed in comparable applications. Additionally, the diameter of the seamless pipes that may be created is limited; typically, it is up to 60 inches. The diameter of the welded pipes can reach 100 inches. Due to this dimensional decision, welded pipes are preferred over seamless pipes in several applications.


Seamless vs Welded Pipe
Parameter Seamless Pipe Welded Pipe
Length Relatively shorter in length due to manufacturing difficulties. Can be manufactured in long continuous lengths.
power Ready to withstand more weight and burden as there is no feeble crease. Because of welding they are accepted to withstand 20% less weight and burden when contrasted with consistent line.
Size Manufactured for nominal size 24 inch or less. No such size restriction on production.
Surface Quality Rough due to extrusion process Smooth high quality surface as compared to seamless pipe.
Corrosion Resistance Less prone to corrosion, means more corrosion resistant. Weld areas are more prone to corrosion attacks, means less corrosion resistance.
Economy Costlier More economic
Tests Seamless pipes does not require testing for weld integrity. Must be tested before use.
Production Process Complex, long procurement lead time Simpler, short procurement lead time.
Ovality Better ovality, roundness Poor ovality and roundness as compared to seamless counterpart.
Availability Less available, limited material types, longer delivery time Readily available for various different materials; shorter delivery time
Application Suitable for high presure temperature and corrosive environment Normally used for less corrosive and low pressure environment.
Wall Thickness Inconsistent wall thickness across length, thicker so heavier Wall thickness more consistent than seamless ones, thinner
Internal surface check Checking not possible Internal surface can be checked before manufacturing