Welded pipe is generally divided into straight seam welded pipe and spiral welded pipe two types.

Welding process

From the welding process, Welding method of the spiral welded pipe and straight seam steel pipe is consistent, but the straight seam welded pipe will inevitably have a lot of t-shaped weld, so the probability of weld defects is also greatly improved, and the t-shaped seam welding residual stress is larger, the stress state of the weld metal are often in a three-way increases the possibility of a crack.And, according to the regulations of submerged arc welding process, each weld shall have arc and arc in, but every straight seam welded pipe when weld girth, can not meet the conditions, thus there may be more at arc welding defects.

ERW pipes- A plate rolled to become a pipe and welded using Electric Resistance Welding process.

(HFI) High frequency welded pipe- HIGH-FREQUENCY WELDING is a welding process in which the heat source used to melt the joining surfaces is obtained from high-frequency (HF) alternating current (ac) resistance heating.

(EFW) Electric Fusion Welded Pipe- The EFW pipe divison consists of a JCO forming press, helical / spiral mill, inside and outside welding system, heat treatment furnace and testing facilities.

(LSAW) Long-Submerge-arc Welded - in leaflets plate as raw material, the steel plate in the mold or molding machine pressure (volume) into using double-sided submerged arc welding and flaring from production.

(DSAW) Double Submerged Arc Welded- is available in straight and spiral welded formats and used in a variety of applications.

(UOE) Uing and Oing forming pipe- the formed pipes are welded inside by five internal welding stations with three wires for each weld,and welded outside by four external welding stations with three wires for each weld.

(JCOE) J-ing, C-ing and O-ing- process with characteristics of high forming accuracy and efficiency as well as balanced distribution of forming stress.

(SSAW) Spiral submerged-arc welding- is its forward direction and forming tube centerline hose reel molding angle (adjustable), side molding edge welding and weld them into a spiral.

(SAW) Submerged arc welding pipe- is a common arc welding process.