ISI marked Steel tubes galvanized to IS 1239 (Part 1) : 2004 with amndt.4 in random length of 4 to 7 mtrs. screwed at both ends as per IS: 554/1999 with Amndt. No. 1, Socketed at one end and other end protected with plastic thread protector in 40 mm bore and Medium Class. Socket confirming to IS: 1239 (Part 2) : 2011 medium class of G.I. pipes.