Concealed Drainage Piping Installation

SCOPE AND PURPOSE

This "Method Statement" provides a detailed account of the installation and testing of concealed drainage pipes in toilets from Level 1 and up for a residential/commercial project.

REFERENCE DOCUMENTS

· Project Specifications
· Approved shop drawings (latest revision)
· Approved material submittals

GENERAL

Installation of drainage pipes within the concrete slab in toilets, garbage rooms, balconies, etc from level 1 and up in towers, shall be done in accordance with the project specifications and drawings.

EQUIPMENT

· Spirit Level, Water Level
· Measuring tape, Nylon twine
· Pipe cutter, Hack saw, Files, Trimmers, etc
· Marking tools, Plumber's toolbox, Hammers

RESPONSIBLE PERSONNEL

· Project Engineers
· Site Engineer/Site supervisor
· QA/QC Inspectors
· Safety officer
· Site Foremen
· Plumbers
· Helpers

METHOD OF PRE INSTALLATION

1. Approved materials shall be purchased in accordance with the approved shop PE/SS drawings and Construction Contract Specifications.
2. Proper materials including pipes and fittings are to be selected and used PE/SS according to approved shop drawings and good engineering practices.
3. Adequate stock of material, tools and tackles, testing equipment, and PE/SS consumables along with sufficient manpower shall be arranged to carry out the work.
4. Site supervisors are to be provided with the civil work schedules for the following works:
   a. Shuttering works
   b. Bottom Reinforcement fixing works
   c. Top Reinforcement fixing works and
   d. Concreting works
5. Site supervisors are to be provided with the finished floor level as well as the structural floor level by the civil surveyors at the site before starting to mark the pipeline route on shuttering.
6. Ensure that the location of masonry walls, concrete walls, shafts, grid lines, etc are marked by the main civil contractor on slab shuttering.
7. The thickness of plastering, tiling, etc with tile modules and thickness of screed and flooring is to be finalized and produced at the site before execution of piping work.
8. Ensure that the construction power and water for testing of pipes are provided by the main contractor near the workplace.
9. Safe and tidy workplace, clear access to the workplace, modes to shift material, tools, and tackles, etc are to be ensured.
10. Civil works including reinforcement schedules should be designed to accommodate the drainage pipes with proper slope and level.

PIPING

1. Main Contractor's Surveyor to mark the locations of Floor gullies, sanitary fittings, etc as per the approved shop drawing and revised architectural drawing on shuttering before putting the reinforcement. Information regarding completion of marking to be given to VL Supervisors etc.
2. Main Contractor to fix bottom reinforcement and inform VL supervisors. VL is to install all pipes and fittings as per the approved shop drawing and as follows.
   i. Ensure that the pipes are cut square before they are placed inside the reinforcement.
   ii. Use cleaning fluid on both surfaces to be joined. This removes all dirt and machine-release agents for the chemical solvent weld. Failure to do this can result in joint failure.
   iii. Apply solvent cement evenly over the mating surfaces of both pipe and socket.
   iv. Insert the pipe into the socket with a slight twisting action to full socket depth.
   v. Surplus cement should be removed with a cloth.
   vi. The joint should be firm enough to handle in 5 minutes.
   vii. Pipe runs are to be placed and tied to reinforcement considering proper slope and gradient as per approved shop drawings.
3. Pipes and fittings which are push-fit types are to be connected as follows:
   
   i. Lubricate the pipes cut in square and chamfered as well as fittings with rubber lubricant and push fit to full socket depth.
   ii. Withdraw pipe 5 mm on the waste system and 10 mm on the soil system to allow for expansion.
   iii. Soil fittings with spigot ends should be inserted into sockets to have depth marks engraved on the spigot.
   iv. This procedure automatically allows for expansion.
   v. Pipe runs are to be placed and tied to reinforcement considering proper slope and gradient as per approved shop drawings.
4. Main Contractor to install Top reinforcement in the slab taking adequate care to ensure that drainage pipes/fittings are not damaged/disturbed etc. VL to ensure that pipes are tied securely to the bottom, top reinforcement, and stirrups so that they are not displaced at the time of concreting.
5. All Fire Stopping related works to MEP services viz. pipes entering/exiting Fire rated Walls etc to be done by Main Contractor.

TESTING

1. Hydraulic testing of the pipes jointed with solvent cement should be done after 1 hour of jointing.
2. Check for gradient and slope before filling the water.
3. Extend one of the pipe ends to attain the required head of 1.5 m for hydraulic testing.
4. Compression-type rubber plugs are to be used to plug all open pipe ends.
5. Fill the entire pipe network with fresh clean water up to the required height of 1.5 m from the highest point.
6. Keep the water with the head required for 6 hours for testing.
7. Check the joints for any leakage and also the fall in water level in the Vertical Pipes. Any leakage found is to be rectified immediately and tested again.
8. Concreting is to be done only after hydraulic testing of pipes has been successful and witnessed by the engineer.
9. Concreting is to be poured over the pipe using mortar pans and compacting such that needles do not touch the hydraulically tested pipes. Main Contractor to ensure that the pipes/fittings etc are not disturbed during concreting operations. This is critical to ensure alignment of pipework is maintained as well as preventing damage.
10. Water filled into pipes is to be retained and monitored for the entire duration of concreting so that any displacement of joints and, subsequent leakages can be monitored.
11. If the above-mentioned situations arise, concreting over that particular area is to be stopped, 'and rectification of displaced, pipes,' sealing of joints, etc to be taken up immediately. The main contractor is to wait until the rectification is carried out properly to VL Supervisor/Foreman's satisfaction.
12. Follow items 1-8 above after rectification.

POST-INSTALLATION PROCEDURE

1. Ensure to prepare As-Built Drawings as soon as possible after the work is completed.
2. The location of the concealed drainage piping will be marked on the suffix as per As-built or redline (As built marked up) drawings to avoid any drilling or related activity to prevent damage to the concealed drainage piping.

QUALITY CONTROL

• QC Engineer along with Project Engineer and Site Supervisor will monitor that all components are installed as per the contract specifications and approved submittals.
• Inspection Request (IR) shall be submitted to the Main Contractor/Consultant during the following stages of work has been completed.
  
  Inspection of Piping installation and hydraulic testing

SAFETY

• Work will commence as per safety regulations laid down in the contract specification and project safety plan.
• Proper safety harness to be used and secured, if required.
• All personal protective equipment shall be used as appropriate according to the nature of the job.
• Housekeeping shall be of good standard and all cut lengths and debris shall be removed.

References:

MEP Planning Manual by Mr. Gulshan Kumar