DSAW, ERW, SSAW, LSAW, EFW Steel Pipe

Welded pipe can be pided into ERW, SSAW, LSAW, EFW:
ERW: Electric resistance welding pipe  
EFW: Electric fusion welding pipe  
SSAW: Spiral submerged arc welding pipe 
LSAW: Longitudinal submerged arc welding pipe
Among them, SSAW and LSAW are both called DSAW: Double side submerged arc welding pipe