Steel tubes- Galvanized ' ISI ' IS: 1239 ( pt- 1 )/ 2004 in random length of 4 to 7 meters, screwed at both ends as per IS: 554/ 1999 Rev- 4 Amndt. 1, screwed at both ends and socketed at one end and other end protected with plastic thread protectors light coated class medium, nominal bore size 50 mm.