Jagvir Goyal

1        While buying G.I. pipes, buy these yourself and don't leave their purchase to the plumber. Medium class pipes are also called B Class pipes. Remember that GI pipe categorization is in reverse order. Class A pipes are lightest and cheapest and Class C pipes are heaviest and costliest. Best combination will be to choose C class pipe outside the building and B class pipe for internal water supply network.  A ½” diameter B class GI pipe costs about Rs. 70 per metre length or about Rs. 22 per foot length these days.

2        A visible mark for a B class pipe is that it carries a blue band of 3 inch length at each end of its 6 metres or 20 feet length. Screwed or socketed part is included in this 6 metre length. A Class pipes carry yellow bands and C class pipes carry Red bands. Scratch the blue band a bit to check that blue colour has not been painted over the yellow to deceive you. You may look for IS 1239 mark on the pipes. IS 1239 is for steel tubes to be used for carrying water. By checking this mark, you will be sure that only ISI marked pipes have been galvanized. Choose a reputed brand. Tata, Jindal (Hissar), Zenith, Kalinga are some of the reputed brands.

3        GI pipes can also be checked by weight. A class pipes are lightest and C class pipes are heaviest. Weights of commonly used diameters of these pipes are as under:

4        Must choose GI pipe fittings and specials of a reputed brand. SVW, UNIK and U are some of the reputed brands. Never choose square elbows for right angles. These obstruct the flow of water. Always prefer a bend than an elbow as a bend has large bending radius and doesn’t obstruct flow. Wherever an elbow is to be used, use a round elbow instead of a square elbow. However, plan such a layout that the number of bends in it is minimised. 

5        Ask the plumber to examine the threads at the end of pipes. The threads must be available for full length and depth. Otherwise ask the plumber to use his threading tool to correct the threads. To keep the threads perfect, the couplings over pipes should not be removed till last moment and threads should be bared only when the joints are to be made.

6        Never allow bending of GI pipes. Instead, use bends where necessary. Never allow heating of GI pipe. It will destroy its galvanizing. Tell the plumber to tighten each joint by use of wrench and to make it watertight.  Here, skill of the plumber comes to the fore. That’s why the plumber chosen must be very skilled and should be chosen after checking his past record. Instead of believing in plumber’s words, visit the houses where he has worked previously and talk to the house owners to check if they are facing any leakage problems. 

7        Use best quality cotton yarn thread in the joints. Never allow use of jute or hemp instead of cotton yarn. Laxmi is a known brand of thread. Use of yarn should be kept minimum. Unnecessary winding of yarn over pipe threads will result in loosening of joint after sometime. Use best quality white lead available at about Rs. 50 per kg for smearing over the thread. Plumber should make a paste of dry red lead mixed with moist white lead and boiled linseed oil. This mixture settles the yarn well into the pipe threads. Otherwise, yarn has a tendency to rise and loosen itself.

8        There are concealed stopcocks to be fixed in the pipelines. In addition, some Tees are to be inserted in them to screw in nipples or other fittings at a later stage. Check all these Tees and specials to be perpendicular to the pipeline. Otherwise, later on, the CP fittings will look obliquely placed or a gap will exist between their wall flanges and the walls. To check this, prepare a couple of threaded pipe pieces and screw them into the Tees and check them to be at right angles to the wall.

More tips will follow next week. Till then, happy building!