Preparation Work
Before commencing the work specified in this section, ensure that: The underground drainage system is ready to receive rainwater or that water discharge can be dispersed by approved means to prevent damage or structural deformation of the building.
General Work
Installation should avoid all existing services. The contractor is responsible for surveying conflicting services and the roof/gutter areas before starting detailed design.
Install piping/outlet systems to ensure complete drainage of rainwater from the building without leakage.
Avoid contact between different metals and materials that could lead to electrolytic corrosion.
Adequately protect the piping/gutter system from damage and deformation during construction. Temporary caps should be made fit for purpose to prevent debris ingress. Fit all access covers, cleanouts, and blanking plates as work progresses.
Unless otherwise specified, use galvanized, sherardized, zinc-coated, or non-ferrous fasteners suitable for the purpose and environment and compatible with the material being fixed.
Construction Work
Comply with restrictions on cutting holes, chases, grooves, etc., and the methods of attachment to the building structure as specified in local or national guidelines.
Installation of Siphonic Inlets
Ensure that:
Siphonic inlets are securely fixed before connecting to the piping system.
Connections between the outlet and the piping system can accommodate any movement in the structure and piping system.
Installation of Siphonic Pipes
Position the piping system neatly, securely, and adequately to prevent movement under severe operating conditions, including pressure fluctuations and vibrations.
Position pipes with the specified number of joints, bends, and offsets, precisely according to the manufacturer’s drawings.
All piping systems must be fully accessible for repair or replacement unless otherwise specified or instructed.
Provide additional supports as necessary to support joints and changes in direction.
Finished pipes must be smooth, of uniform bore, clean, and free from deformation, wrinkling, cracking, and other defects.
Pipes, joints: Clean off the coating after cutting and repair any damage or re-coat, as recommended by the manufacturer.
Marking and identification of pipes: In accordance with BS 1710 standards, using self-adhesive bands or identification clips located at joints, on both sides of each plate, partition, wall penetration, and elsewhere as directed.
General Inspection
Give sufficient notice to the Supervisor for them to have a reasonable opportunity to observe inspections.
Check that all parts of the installation are free from blockages and debris before testing.
Provide clean water, assistance, and testing equipment as required.
Conduct tests as specified. After testing, identify and immediately rectify all faults and retest as directed.
Keep records of all test documentation and provide a copy of each test to the Consultant.
Pipe Tightness Testing
- Temporarily seal open ends of the piping system with plugs or stop valves.
- Connect a U-tube water gauge and an air pump via a plug.
- Pump air into the piping system until the gauge indicates 38 mm.
- Allow a period for temperature stabilization, after which the 38 mm pressure shall be maintained without loss for at least 5 minutes.
Gutter Testing
Block all outlets, fill the gutter to the overflow level, and after 5 minutes, inspect thoroughly for leaks.
Pre-Handover System Inspection
- Remove construction waste and debris from all roofs and gutters. If possible, sweep and remove fine dust that could enter the rainwater system. Do not sweep or flush dust or debris into the rainwater system.
- Remove debris, fragments, and temporary caps from the entire rainwater system.
- Ensure that all access covers, inlet grates, etc., are completely secured with all fixtures.
Source: https://en.hydrotech.vn
