Case 1

Maintenance and Diagnostics

Regular maintenance and water testing can help identify chemical corrosion early on and prevent future failures. Periodic inspection and tests can be advisable to ascertain any other defects such as water leakages. Checklists could be used so that a thorough checking could be made. Defects could be recorded, monitored and not be left unattended.

PUB maintains the water pipes up to the meter for landed properties and the master meter for residential
and commercial blocks. The maintenance of the water supply system between these meters and the sub-meters is managed by town councils for HDB homes and the building management for condos and commercial buildings. Home owners are responsible for pipes in their own premises and should get them checked yearly. Carry out quarterly chemical and bacteriological analyses of the water used. Perform monthly checks of the water supply for visual signs of leakage, scaling and corrosion of pipes, joints, valves and taps, and mixers. Increase the frequency of inspection for damp or polluted areas in accordance with BS 8554 or equivalent. Carry out monthly inspections and clean off / remove any rust
or scale. Re-paint parts in a timely manner, if needed, in accordance with BS EN 806-5 or equivalent.
Replace corroded water fittings promptly. Replace unlined galvanised iron pipes with cement-lined
ductile iron or copper pipes to prevent corrosion.

Diagnostics of Defect (see also NDT)

Fibrescope / Borescope

This instrument is useful when services are concealed. There have been many cases of collapse of large area of false ceiling, due to weight of accumulation of water or condensate. Regular inspection using a fibrescope/borescope could prevent such accidents.

A fibrescope or a flexible borescope is a flexible optical inspection device that consists of fibre optic bundles with an eyepiece at one end and a lens at the other.

A fibrescope usually comes in two bundles: (i) a fibre optic light bundle that is for illuminating the object to be investigated, and (ii) a fibre optic image bundle to relay the image to the eyepiece. It allows a direct visual inspection for an otherwise inaccessible part, as observations of remote, difficult-to-reach areas can be made through a video monitor with high-resolution images. The flexible fibres allow it to be manoevred in hard-to-reach or inaccessible areas.

It is often used to verify findings from other tests, such as infrared thermography or impact-echo testing.
Common applications include:
– Inspection of connecting condition behind the external cladding wall of a building.
– Inspection of defects on concrete surface(s) in a deep and narrow gap.
– Determination of corrosion condition of steel tendon(s) inside post-tensioning ducts of pre-stressed structural member(s).
– Investigation of service pipes, ducts and other inaccessible areas.