square/ rectangular pipe standard:GB/T6728-2002 ASTM A500Gr.A,B JIS G 3466 Standard length:6M,/12M GB Grade: Q195 The above are the main supplying sizes. If other sizes outside the list are required, please contact with us . we can supply pipes according to the specific requirement and usage of buyers.Galvanized, black and brighten square/ rectangular pipe are available service of painting the pipe with varnish or oil, threading and socket the pipe ande put on plastic cap are available. our web address: