We use strip steels or steel plates as billets, bend them into tube shells with different methods, and then weld them with different ways so as to obtain welded pipes with sealed cross sections formed by a certain strength welding seams. There is a wide range of materials for producing welded pipes, including carbon steels, alloy steels, high alloy steels, nonferrous metals and nonferrous alloys.

Welded pipes have a wide range of applications in the national economy.   
(1) Welded pipes are mainly used to transport a variety of fluids, such as oil and natural gas. 
(2) Welded pipes are widely used for infrastructure, mainly for water, central heating and gas transportation; welded pipes with large diameters are also widely used as basic steel piles for buildings, bridges, harbors and machinery.
(3) Welded pipes are quite common in machinery manufacturing, light industry, automobile, agricultural machinery and other sectors. Especially with the appearance and development of welded pipes with high strength and high precision, seamless pipes with expensive cost are even replaced by welded pipes in many fields.
(4) SSAW pipes with large diameters are used for chemical process vessels, storage tanks, etc.
(5) The emergence of welded pipes with high alloys and rare metals expands applications of welded pipes.

What are the advantages of using welded pipes to deliver fluids?
(1) Welded pipes have low infrastructure costs and can save 1/3 of infrastructure costs compared with railway transportation. They have twice delivery capacity of railway transportation.
(2) With simple and fast construction, welded pipes are generally laid underground and are safe, reliable and adaptive to a variety of terrain.
(3) Welded pipes have low operating costs and can obtain high automation. Compared with other transportation, pipeline transportation is the cheapest. Costs of pipeline transportation are only 1/10 of the railway transportation, and about 1/2 of the waterway.

What are the characteristics of welded pipes compared with seamless steel pipes?
(1) Welded pipes have simple technical processes of production.
(2) Welded pipes needs less facilities, and have simple structure as well as light weight, which can help continuous, automated and mechanized production.
(3) Welded pipes have low costs.

What are production methods of welded steel pipes?
Forming and welding are the basic processes of welded pipes, and classification of welded pipes' production methods are based on them. We can classify welded pipes into furnace welding, electrowelding, gas welding and electrogas welding pipes according to the welding methods.