Code of practice for laying glazed stoneware pipes
1983 Edition

As per the standard, concrete bedding is mandatory when pipes are laid on soft soils with the water table at invert level. Alternatively, precast concrete sleepers with 90-degree contact may be used over swelling soils, subject to approval. A sand cushion of suitable thickness is also acceptable. For backfilling, sand, fine gravel, or other authorized materials should be placed in layers approximately 80 mm thick and compacted by tamping. Backfilling should be executed simultaneously on both sides of pipes and fittings to ensure uniform support and prevent joint contamination.

Trenches must be excavated to widths defined by pipe diameter plus an additional 300 mm for depths up to 1.20 m and 400 mm for deeper trenches, with a minimum width of 0.75 m for depths exceeding 0.9 m. The minimum cover under roadways should be 90 cm, adaptable to local conditions. Excavation should proceed only as far as pipe laying progress allows. The trench bottom must be level and smooth; if rock or boulders are encountered, the bottom should be trimmed at least 80 mm below the pipe base and filled with well-compacted broken stones passing a 12.5 mm sieve, ensuring adequate joint space.

The code permits cement and bituminous joints for glazed stoneware pipes. Cement joints involve applying cement mortar between the socket and spigot after cleaning and moistening, ensuring proper thickness and curing for waterproofing. Bituminous joints consist of a boiled mixture of asphalt and sand in a 1:7 ratio poured into the socket to create a flexible, sealed joint. If joints leak, they must be repaired or encased in a 150 mm thick cement concrete sleeve over a 300 mm length and retested to confirm integrity.

Hydraulic testing requires filling the pipeline with water and applying a test pressure typically about 1.5 times the working pressure or as mandated by local regulations. This pressure should be maintained for at least 30 minutes while monitoring for leaks or pressure drops. Prior to testing, joints must be properly formed and sufficiently cured. The test is passed if no leakage or unacceptable pressure loss occurs; otherwise, repairs are necessary followed by retesting.

Under roadways, a minimum cover of 90 cm over the pipes is recommended, adjustable based on site conditions. To protect pipes from heavy traffic loads, reinforced concrete slabs may be installed over the trenches. Pavement removal should not extend more than 150 mm beyond trench edges without approval. Trenches must be properly shored and drained for safety. Additionally, pipe socket ends should face upstream or upgrade to prevent foreign material ingress, ensuring structural protection and longevity under traffic.