Difference between seamless and welded pipe
Publish Time: 2020-10-13 Origin: Site
Seamless pipe is made from a round steel billet (solid cylindrical hunk of steel that is cast from raw steel). This billet is then heated, stretched out and pushed or pulled over a form. It is then pierced through the center with a die and mandrel which increases the inside diameter and reduces the outside diameter.
Welded pipe is made by cold forming flat strip, sheet or plates into a round or circular shape by a roller or plate bending machine. The pipe is then welded with or without filler material using a high energy source.
From the above introduction,we could see the difference between seamless and welded pipe:
| Sr. No | Parameter | Seamless Pipe | Welded Pipe |
| 1 | Strength | Able to withstand more pressure and load as there is no weak seam. | Due to welding they are believed to withstand 20% less pressure and load as compared to seamless pipe. |
| 2 | Length | Relatively shorter in length due to manufacturing difficulties. | Can be manufactured in long continuous lengths. |
| 3 | Size | Manufactured for nominal size 24 inch or less. | No such size restriction on production. |
| 4 | Corrosion Resistance | Less prone to corrosion, means more corrosion resistant. | Weld areas are more prone to corrosion attacks, means less corrosion resistance. |
| 5 | Surface Quality | Rough due to extrusion process | Smooth high quality surface as compared to seamless pipe. |
| 6 | Economy | Costlier | More economic |
| 7 | Production Process | Complex, long procurement lead time | Simpler, short procurement lead time. |
| 8 | Tests | Seamless pipes does not require testing for weld integrity. | Must be tested before use. |
| 9 | Application | Suitable for high presure temperature and corrosive environment | Normally used for less corrosive and low pressure environment. |
| 10 | Availability | Less available, limited material types, longer delivery time | Readily available for various different materials; shorter delivery time |
| 11 | Wall Thickness | Inconsistent wall thickness across length, thicker so heavier | Wall thickness more consistent than seamless ones, thinner |
| 12 | Ovality | Better ovality, roundness | Poor ovality and roundness as compared to seamless counterpart. |
| 13 | Internal surface check | Checking not possible | Internal surface can be checked before manufacturing |