Method Statement for Drainage Pipe Installation – PVC uPVC Drainage Piping Under / Above Ground

This method statement is applicable for all drainage pipe works underground, above ground, horizontal and vertical drainage piping for any kind of the project as specified in project specification.

It is responsibility of project manager and project plumbing engineer to ensure the availability of coordinated drawings and the required materials as per the project specifications.

Piping will be installed by the experienced foreman/pipe fitters in the supervision of site engineers.

Inspection and Testing Requirements

All drainage Installations shall be inspected in accordance to the Inspection and testing plan & inspection checklist.

Perform the inspections on completion of reasonable part of work area wise or block wise as per consultant requirements. Generate an inspection request along with inspection checklist and after completing internal inspection call the consultant for witnessing the work inspection.

Most of the cases site QC engineer and site engineer shall witness and accompany the inspections.

Drainage pipe shall be tested as per the checklist. Within the building the plug piping section shall be tested by filling it with water at highest point, and test shall be carried out in floor intervals not higher than ten meters.

Between manholes pipes shall be tested by plugging the inlet pipe to the upstream manhole and inlet pipe of the downstream manhole and filling the water to the top of the upstream manhole. No apparent loss of water should be noticed after four hours.

Results of Inspection & testing shall be recorded properly by QA/QC/Site engineers.

Health & Safety Measures

• Risk assessment for all activities has been carried out and attached as annexure , all necessary control measures should be taken as mentioned in the risk assessment.
• Adequate safe access to the Installation area shall be provided.
• Workmen shall wear all appropriate safety personnel protective equipment such as helmet, coverall clothing, safety shoes, goggles and gloves etc. wherever required.
• If work is at high level, only approved scaffolding and safety belts should be used.
• Sufficient light shall be ensured before start of the work.
• Safe work permit shall be obtained where required as per the directives of HSE department.

Technical Submittal Requirements

• All materials submittals shall include a detailed, clause-wise, compliance statement with the specifications.
• All materials submitting shall include detailed catalogue, product literature and descriptions of all equipment and fittings with selection charts, capacities etc.
• All material submittals shall include copies of pages of relevant standards.
• Provide detailed shop drawings of the items or equipment being provided, indicating the dimensions, materials and characteristics.

Required Materials

Pipe and fittings shall be in conformance with the following unless specified otherwise by local authorities.

uPVC Pipes & Fittings:

• The drainage pipe work and fittings shall be of un-plasticized rigid type and of high density.
• Non pressure PVC pipe and fittings to be complying BS 5255 for 32, 40 and 50 mm pipes and to BS 4514 for 110 and 125mm.
• Sealant on PVC pipes to be provided for expansion and contraction to BS 2494 standard.
• All pipes of diameter under 110mm shall be adhesive type jointed and above 110mm shall be rubber type jointed, and all fittings shall be selected accordingly.

Floor Clean-outs

Floor clean outs shall be provided as per the locations on shop drawings. Depending upon the connection it may be either 45 degree Roding eye or straight Roding eye. It should be uPVC material and should be supplied with cap, chrome plated copper plate and cover of overall size 200mm x 200mm.

Floor Drains

Each floor drain shall be of UPVC construction with 700mm water seal. Drain shall be fitted with 25mm access plug for cleaning purposes and shall be of the same material as the pipe connected to it.

Installation / erection procedure for drainage pipe

Prior to installation, the following will be observed and checked, as applicable:

For temporary storage of the pipes in the site where racks are not provided the ground shall be level and free from loose stones.

Also the pipes shall be stacked to prevent movement.

UPVC Pipes shall be protected from the direct rays from the sun by covering the pipes with polythene sheets or similar material.

Ensure the pipes are free from dust and damages prior to installing.

General Installation Requirements

Drainage and vent piping shall be installed at the following minimum slopes if not specified anywhere else.

Sanitary building drain: 1 percent for piping 80mm (3”) and smaller; 1 percent for piping 100mm and larger

Storm water building: 1 percent.

Hangers and Support Installation Guidelines

The following shall be used as guidelines.

Trench Preparation for Underground Drainage Pipes

• The contractor shall carry out the excavation for the trench depending on the pipe diameter, type of ground and depth of lying.
• Bedding for pipes shall be constructed by spreading and compacting Approved bedding material over the whole width of the pipe trench.
• After the pipes have been laid, additional material shall, if required, be placed and compacted equally on each side of the pipe, and where practicable, this shall be done in sequence with the removal of the trench supports.
• Where pipes are required to be bedded directly on the trench bottom, the final excavated surface shall be trimmed and levelled to provide even bedding for the pipeline and shall be free from all extraneous matter that may damage the pipe.
• Where rock is encountered, the trench shall be cut at least 150 mm deeper than other ground and made up with well compacted selected fill material.

Pipe Laying and Installation

• All pipes are laid with due regard to the fall and invert levels set out in the shop drawing.
• Where pipes requiring the socketed joints are required to be installed directly on a trench bottom, on granular /sand bed, joint holes/spaces shall be formed in the bedding material or final excavated surface to ensure that each pipe is smoothly and uniformly supported throughout its length.
• No protective cap, disc or other appliance on the end of a pipe or fitting shall be removed permanently until the pipe or fitting which it protects is about to be jointed.
• Pipes and fittings shall be examined for damage and the joint surfaces and components shall be cleaned immediately before laying.
• Suitable measures shall be taken to prevent soil or other material from entering pipes, and to anchor each pipe to prevent flotation or other movement before the works are complete.

Cutting of pipe

Wherever required, pipe cutting shall be performed by a method which provides clean square cut of pipes and then chamfered as required.

Pipes ends are chamfered to approximately 15^o for half the pipe wall thickness and debarred with a sharp edged tool.

Drainage Pipe Assembly / Jointing Methods

Push-fit jointing

For pipe sizes 82 mm and above, jointing of pipes and fittings are carried out by Push-fit jointing method.

• Before making the joint ensure that both the pipe end and the sealing ring are clean.
• Lubricate both the pipe ends and the sealing ring in the socket with silicone lubricant.
• Ensure that components to be joined (by push-fit method) are correctly aligned, and then push the spigot fully into the socket.
• To allow for expansion, mark the spigot at the socket face and then withdraw the spigot by a minimum of 12mm.
• If the spigot is already marked with the depth of entry, push the spigot home until the mark is just visible.
• The jointing of larger diameters is generally accomplished by applying leverage to the following socket end using a timber block to prevent damage.

Solvent Weld Jointing

Pipe sizes 50mm and below are joined together by the solvent weld method.

The solvent and glue used in this method are Parabond P.14; the MSDS is attached for handling and using these materials.

Since these materials are hazardous to health handling of the material is done in accordance with MSDS and COSHH regulation applicable locally.

Both surfaces to be joined shall be cleaned using a cleaning fluid. This removes all dirt and machine release agents and softens the surface ready for the chemical solvent weld.

The Solvent cement shall be applied evenly over the mating surfaces of both the pipe and socket.

The pipe shall be inserted to the socket with a slight twisting action to full socket depth. Surplus cement shall be removed with a cloth.

The joint shall be firm enough to handle in 5 minutes.

All open ends of the installed pipes shall be plugged with end caps or wrapped with polyethylene sheets to prevent entry of dust & other foreign particles.

Back-filling of Underground Piping

Pipe surround

After pipe laying, Inspection and testing a further 300mm of approved bedding material shall be used for pipe surround, compacted with hand from all sides while tamping lightly over the crown.

The bedding material shall span the entire width of the trench and shall be laid in not more than 150mm deep layers, each layer being compacted by hand.

Main Backfill

This is usually compacted infill with the original trench soil over the layer of pipe surround. Heavy mechanical rammers shall not be used until the fill has reached a sufficient height above the top of the pipe.

Above Ground Drainage Pipes

• All pipe work shall be adequately supported in such a manner as to permit free movement due to expansion, contraction, vibration or other changes in the system.
• All above ground drainage pipes are joined using either Push-fit or solvent weld jointing method.
• Supporting of pipes shall be arranged as near as possible to joints and changes in direction. For supporting of pipes, Galvanized steel Split clamps shall be used.
• All vertical pipes (160mm dia. and below) shall be supported using split clamps screwed to the wall using threaded rods, diameters of which shall be according to the clamps manufacturer recommendations.
• Where soil and vent pipes are suspended from the underside of the slab, they shall be held rigid in position. Based on the pipe diameters, Single or double iron supports shall be used, as required.
• Pipe supports shall be provided at intervals as per Specifications and/or BS Standards.
• Installation shall be started from the base of the stack and worked up. Vertical stacks shall be adequately supported at the base to stand the total weight of the riser.

Site Installation Method Statement for Drainage Pipes

Coordinated drawings and the required material is arranged by the site engineer as per the project specifications.  Piping is installed by the experienced foreman/pipe fitter.

Before start of the work make sure that all the HSE measures have been taken and obtain all the necessary PPE’s. If required get the safe work permit from HSE department.

Procedure for Installation of uPVC Drainage Pipe & Fittings for Drainage System

Perform the piping work as per following sequence:

• Highlighted coordinated drawings for selected pipeline are studied.
• All the material is shifted to appropriate location.
• Support marking is done at the location as per the drawing.
• Enough safety care like safety belts, eye protection is taken in case of work at the heights.
• Drilling of suitable size is done to fix the rawel bolt.
• Anchor bolts / raw bolts are fixed and threaded rod of suitable length is fixed.
• Specified clamps are fitted in the threaded rod.
• Straight Pipes, cleaned from inside, with fittings are inserted and the properly clamped.
• Pipeline thus erected are plugged from both ends at the end of the day work.
• Check request is made for the same and consultants approval taken.
• Pipes are painted with red oxide except joints.
• The straight portions are insulated as per specification and the remaining pipeline is released for the pressure testing.
• After pressure testing the joints are painted with red oxide.

Procedure for External Drainage Pipe Installation

Before start of the work, make sure that, all the HSE measures have been taken and obtain all the necessary PPEs.

• Mark the drainage pipe route with lime powder for excavation of trench as per the approved drawings.
• Check the trench bottom level with leveling instrument to match the invert level of the pipe line as per the approved drawings.
• Provide concrete base with required gradient for a firm base for pipe installation.
• Install the pipe between the manholes as per the specification and approved drawings.
• Provide head vent on the first or starting Manhole.
• Make sure that the maximum distance between manholes should be only 25 to 30mtrs.
• Check the invert level of the pipes after installation.
• Make proper supports after the installation and checking of the level.
• After the checking the level of the installed pipes arrange for testing.
• Fix 2 No’s of 90 degree bends on both the ends of the pipe line and fix about 3 meter height vertical pipe.
• Fill the pipe line with water up to the height of 3 meter.
• Check the pipe joints for any leakage.
• If found any leakage repair it.
• Make inspection request for Consultant/ client approval.

Procedure for Internal Drainage Pipe Installation

Before start of the work, make sure that, all the HSE measures have been taken and obtain all the necessary PPEs.

• Obtain clearance from the civil contractor for installation of Pipes.
• Remove the sleeve box provided in slab / wall for opening.
• Mark the pipe route as per the approved drawings.
• Fix the brackets / supports / clamps as per the specification with proper intervals with required gradient for a proper slope.
• Fix an approved quality Floor trap for waste drainage system with pipes and required fittings as per the approved drawing and connect to the Gully trap.
• Fix a 90 degree Bend for soil drainage system with pipes and fittings and connect it to a nearest manhole.
• Fix the uPVC waste lines from the wash basin, bath tub and bidet and connect to the floor trap with boss connector.
• Provide cleanouts at every 20mtr and every turning point.
• Provide Vent pipe for each system.
• Fix flexible connectors on the building expansion joints.
• Fill water for leakage test of all the drainage pipes.
• If found any leakage repair it.
• Make inspection request for Consultant/ client approval.

Procedure for Vertical Drainage Pipe Installation

Before start of the work, make sure that, all the HSE measures have been taken and obtain all the necessary PPEs.

• Obtain the Civil clearance from the main Contractor for the shafts/ducts where the piping works to be carried out.
• Inspect the shafts/ ducts for wall plastering & water proof treatment etc. if any.
• 
• Mark the pipe location as per the approved coordinated shop drawing.
• Fix the supports/brackets in proper intervals as per the standard with approved quality materials.
• Install the vertical Soil pipes with “T” or “Y” provision for Water closet branch connection from Toilets
• Install the vertical Waste pipes with “T” or “Y” provision for Waste pipe branch connection from Kitchen / Baths Rooms & Traps.
• Terminate the vertical stack 1 meter above the parapet wall and install vent cowl on the top.
• Check with plumb level for Verticality of the pipes after installation.
• Make the supports rigid after checking of the Plumb level.
• Connect the branch lines to the Vertical stack.
• Provide cleanout points at 1.20 meter height from the finish floor level.
• Close all the branch lines for Smoke/Water leak test up to 2 levels or 6 meter height.
• Fill the pipe line with Water or Smoke.
• Inspect the joints for any visible leakage or with soap water.
• If found any leakage repair it.
• Make inspection request for Consultant/ client approval.