This code of practice offers comprehensive instructions for choosing, handling, storing, installing, joining, and testing polyethylene (PE) pipes specifically for potable water systems. It addresses both underground and above-ground pipeline setups, detailing trench preparation, pipe supports, and various jointing methods such as butt fusion, electrofusion, and compression fittings, ensuring durable and leak-resistant installations suitable for water temperatures up to 45°C.
Overview
This code of practice offers comprehensive instructions for choosing, handling, storing, installing, joining, and testing polyethylene (PE) pipes specifically for potable water systems. It addresses both underground and above-ground pipeline setups, detailing trench preparation, pipe supports, and various jointing methods such as butt fusion, electrofusion, and compression fittings, ensuring durable and leak-resistant installations suitable for water temperatures up to 45°C.
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Frequently Asked
According to the standard, for small-diameter PE pipes (less than 110 mm) operating at or below 1.6 MPa, polypropylene compression fittings are generally the preferred choice over fusion methods. Jointing can occur inside or outside the trench with appropriate workspace considerations. The standard endorses fusion jointing methods including butt fusion, electrofusion, and socket fusion for all pipe sizes, while mechanical compression fittings are especially suitable for smaller diameters.
Trench preparation requires ensuring absence of sharp objects near the pipe, with no special bedding necessary in normal soil but a compacted sand bedding of 100 mm thickness is recommended in rocky or unconsolidated soils. The trench width should accommodate the pipe diameter plus an allowance for jointing workspace if jointing is done in situ. Backfilling should use screened, granular materials free from sharp stones, compacted carefully to avoid pipe damage, with native soil layered and compacted above the initial backfill.
PE pipes should be stored away from excessive heat and harmful chemicals. Though exposure to sunlight doesn't degrade their performance, heat can cause bending, so pipes must be stored on level surfaces with adequate support. Handling should avoid dragging pipes over rough or sharp surfaces; mechanical aids are recommended for pipes exceeding 160 mm diameter. During transportation, bundling and wrapping coils protect pipes from abrasion and movement, ensuring integrity throughout.
Electrofusion welding involves joining PE pipes using fittings embedded with electrical resistance wires. The process starts with preparing pipe ends by cutting squarely, cleaning, and marking insertion depths. Pipes are inserted into the fitting, secured with clamps, and connected to an electrofusion machine that heats the wires to melt and fuse the pipe and fitting material. The machine controls heating and cooling cycles automatically, ensuring a reliable, leak-proof joint. Cooling must be allowed as per manufacturer’s instructions before handling.
The pipeline is slowly filled with water, venting trapped air via valves at high points, then allowed to stabilize for one hour at ambient temperature. Testing pressure is set to 1.5 times the maximum design pressure, maintained by continuous pumping and topping-up water as needed for 1.5 hours. No air is used in testing. The pressure variation must stay within ±5% with no leaks. If leakage occurs, the system is depressurized and rested for eight hours before retesting. Simultaneous backfilling on both trench sides and layered compaction after testing ensure pipeline protection.
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