HDPE PLB Duct Pipes

PLB stands for Permanently Lubricated Bore. It is an HDPE duct pipe with a silicone-based lubricant layer co-extruded into the inner wall during manufacture — not applied as a coating. This permanently reduces friction so optical fibre cable can be blown through over long distances.

They solve different problems. PLB duct is a smooth-wall, dual-layer pipe with a lubricated bore (coefficient of friction ≤ 0.06) designed for blowing optical fibre cable over 1,000+ metres. DWC (Double Wall Corrugated) pipe has a corrugated outer wall for crush strength and is used to protect power and telecom cables that are pulled, not blown. PLB is specified by TEC; DWC by IS 16025.

PLB duct is designated by an OD/ID pair. Standard sizes are 25/20mm, 32/26mm, 40/33mm, 50/42mm and 63/51mm. The 40/33mm size is the most widely used for backbone optical fibre networks; 25/20mm is common for FTTH last-mile connections.

Cable is installed in PLB duct by blowing it in with compressed air rather than pulling it. A coefficient of friction of 0.06 or lower — versus roughly 0.15–0.25 for plain HDPE conduit — is what allows blowing speeds up to 100 m/min and continuous runs beyond 1,000 metres without intermediate access pits. That directly reduces excavation, jointing and installation cost.

For the product category as a whole, the finished duct is specified by the TEC (Telecommunication Engineering Centre) Generic Requirement, and railway signalling work additionally references RDSO/SPN/TC/45/2006. The polyethylene raw material is covered by IS 7328:2020. TARKO manufactures PLB duct to the standard OD/ID sizes and performance parameters used across the industry; if your tender requires a TEC-approved or RDSO-approved supplier, please confirm your certification requirement with us before ordering.

Colour is used to identify separate networks or operators sharing the same trench — commonly Red, Green, Orange, Blue, Yellow, Grey, Brown and Black. There is no single mandatory national colour code; the scheme is normally fixed by the project or operator. Identification stripes along the duct can also be supplied to customer requirement.

PLB duct is supplied in coils of 200, 500 or 1,000 metres, which keeps the number of joints low over long runs. Lengths are joined with push-fit plastic couplers that seal air-tight and water-tight — essential because the duct must hold air pressure during cable blowing. End plugs seal ducts before cable installation and cable sealing plugs seal them afterwards.

PLB duct is the standard conduit for underground optical fibre in India — BharatNet gram panchayat connectivity, 5G backhaul and tower fiberisation, NHAI and MoRTH highway OFC, smart city utility corridors, railway signalling networks, and FTTH/broadband rollouts by private ISPs.