differentce between ERW pipe and EFW pipe

ASTM A252 Grade 2 pilling pipe
ASTM A252 piling pipe Grade 3 OD 219mm
September 30, 2016
ASTM A53/A53M Standards Specification for Pipe, NPS 1/4 INCH – 30 INCH ,Schedules 10 -160, STD, XH and XXH Welded and Seamless
October 10, 2016