Welded pipe, is a steel pipe made of steel plates or steel coils after crimping and welding. Welded steel pipes have simple production processes, high production efficiency, many varieties and specifications, but their general strength is lower than seamless steel pipes. The typical production process should be: strip raw material → raw material pretreatment → cold bending forming → welding → weld heat treatment → weld (tube body) flaw detection → finishing → finished welded pipe
A. According to the process -- arc welded pipe, resistance welded pipe (High frequency, low frequency), gas welded pipe, furnace welded pipe
B. According to the welds -- straight seam welded pipe, spiral welded pipe
Common English abbreviations for welded pipe:
ERW: electric resistance welding
EFW: electric-fusion welded
SAW: submerged arc welding
LSAW: Longitude submerged arc welding
HSAW: horizontal submerged arc welding
ERW pipes are manufactured from steel coils, that are uncoiled, cut, processed, welded, and tested. ERW pipes are available in sizes between 1/2" and 20", in carbon steel (most in ASTM A53) and stainless steel (ASTM A312).
LSAW pipe (“submerged arc welding”) is manufactured by cutting, bending, and welding steel plates (JCOE process).
LSAW pipe is a must for pipes over 24" (because 24" is the largest size of commercial seamless pipes), it competes with seamless pipes and ERW pipes between the size 16 to 24 inches.
ERW pipes have become an efficient alternative to seamless pipes, both in terms of price and performance, due to the modern welding technologies adopted by ERW pipe manufacturers (example HFI and HFW, high-frequency welding) which can help end-users reduce prices and lead times between 20 and 25%.
Large-diameter API 5L SAWL pipes are used to transport hydrocarbons over long distances efficiently in the oil and gas industry.
HSAW/SSAW spiral weld pipes are used for non-critical applications, as water transmission and distribution (not for oil & gas).