Seamless steel pipe is a round, square and rectangular steel with a hollow section and no joints on the periphery. Seamless steel pipes are made of steel ingots or solid tube billets through perforation into capillary tubes, and then made by hot rolling, cold rolling or cold drawing.

Welded steel pipes refer to steel pipes with seams on the surface that are welded after bending and deforming steel strips or steel plates into round or square shapes.

A53 erw steel pipe

So, what is the difference between seamless and welded pipe?

1. Different materials

①Welded steel pipe: Welded steel pipe refers to steel pipes with seams on the surface after bending and deforming steel strips or steel plates into round or square shapes. The blanks used for welded steel pipes are steel plates or strip steels.

②Seamless steel pipe: a steel pipe made from a single piece of metal with no seams on the surface.

2. Different categories
① Welded steel pipe: According to different welding methods, it can be divided into arc welded pipe, high frequency or low frequency resistance welded pipe, gas welded pipe, furnace welded pipe, Bondi pipe, etc. According to the purpose, it is divided into general welded pipe, galvanized welded pipe, oxygen-blowing welded pipe, wire casing, metric welded pipe, roller pipe, deep well pump pipe, automobile pipe, transformer pipe, electric welded thin-walled pipe, electric welded special-shaped pipe and spiral welded pipe.

②Seamless steel pipes: seamless pipes are divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, and top pipes. According to the cross-sectional shape, seamless steel pipes are divided into two types: round and special-shaped. Special-shaped pipes have square, elliptical, triangular, hexagonal, melon-shaped, star-shaped, and finned pipes. The maximum diameter is 650mm, and the minimum diameter is 0.3mm. According to different purposes, there are thick-walled pipes and thin-walled pipes.

3. Different uses
① Welded steel pipes: can be used as water gas pipes, etc., large diameter longitudinally welded pipes are used for high pressure oil and gas transportation, etc.; spiral welded pipes are used for oil and gas transportation, pipe piles, bridge piers, etc.


②Seamless steel pipes: used as petroleum geological drilling pipes, cracking pipes for petrochemical industry, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.

Know more,pleases refer to:
https://www.nan-steel.com/news/seamless-and-welded-pipe.html