Below procedure for installation of drainage pipe is very useful for all kind of projects and buildings of any size. First step is the procurement of pipes after which these shall be delivered on the site. When off-loading, pipes shall be lowered to the ground either manually or with crane. Timber support of at least 3” wide shall be placed beneath the pipes with spacing not greater than 1.8 meters. Closer supports will be required for sizes below 160mm. Pipes shall not be stored under direct sunlight to avoid ultra violet degradation.
Socketed drainage pipe shall be stacked in layers with sockets placed at alternate ends of the stack and with the sockets protruding to avoid unstable stacks and the possibility of importing a permanent set to the pipes. Longer pipes of thicker class shall be kept at the bottom.
Before installation make sure that drawings for installation of drainage pipe are approved & coordinated with other services. Make sure that location / area is ready for installation of above ground piping.
Drainage Pipe Installation Procedure
Drainage pipe are brought to the work place manually from store to the hoist area and are shifted to the respective floors through the hoist.
Mark-up the pipe routing on the soft fit of slab as per the setting-out. Install anchor fasteners for support as per the approved support distances for different pipe sizes.
All supports of pipes will be provided as per specified spacing both horizontally and vertically. Supporting of both horizontal & vertical pipes shall be done in accordance with the approved details, drawings and specifications.
Pipes will be run to proper slope requirements as per the approved shop drawing. Pipes & fittings will be joined by solvent weld jointing for pipe sizes 1 ¼” to 2”. Following steps will be taken during the jointing.
Solvent Cement Drainage Pipe Jointing Procedure
Pipes will be cut to square before assembly of fittings & all burrs to be rubbed-off. Cleaning fluid to be applied on both surfaces to be joined. The cleaning fluid will remove all dirt & soften the surface for the chemical solvent weld. Solvent cement will be applied evenly over mating surfaces of the both pipe & socket, and insert pipe into the socket with slight twisting action to full socket depth. Surplus cement of the joint will be removed by cloth. After jointing, it will be allowed for 3 minutes to get dried.
Clean-outs are provided to enable the maintenance in case of choking of drainage system at each change of direction. Expansion couplings are provided at necessary locations as per manufacturer’s recommendations & shop drawing. Refer manufacturer’s recommendation to allow for the expansion. All open-ended pipes to be plugged during installation phase.
Pipes & fittings will be joined by push fit method for the pipe sizes 3” to 6”. Following steps taken during installation. Ensure that the mating areas of spigot and socket are thoroughly clean and square.Set the rubber ring into groove. Assess the full socket depth by simple measurement and mark spigot accordingly. Apply lubricant to the spigot side and to the side of the joint on rubber.
Accurate axial alignment of the spigot and prior to jointing is important, hand feed spigot into rubber joint until resistance from the inner sealing section is felt. Complete the joint by applying leverage to the following socket and using a timber block to prevent damage.
Hydro-static Testing of Drainage Pipe System
Water test is conducted to ensure and prove the tightness of the joints and ensure there are no leaks in the piping system. The water pressure test can be applied to the system in its entirety or in sections. No section of the pipe shall be tested to less than 1.5 meter head of water. In testing successive sections of piping, at least the upper 3 meters of the next proceeding section will be tested.
The water shall be kept in the system or in the portion under test for at least 30 minutes before inspection starts. While the system is under pressure, a careful inspection shall be made on all pipes and joints. If any leaks in joints or evidence of defective pipe or fittings are revealed, the defective pipe/fitting should be immediately replaced with new joints and materials.
After the correction is made the test pressure will be maintained for minimum 30 minutes. Drainage pipe gravity testing will be inspected by client / main contractor / consultant to their satisfaction and document for correct test will be maintained by getting approval in test certificate by Consultant and Main Contractor. Work Inspection Request shall be raised for Consultant’s inspection and sign off.