What is a PLB duct?
A Permanently Lubricated (PLB) duct is a HDPE pipe with an integral solid-silicone inner layer that reduces friction and allows optical fiber cables to be blown over long distances. No liquid or grease lubricant is needed — the silicone layer is co-extruded during manufacturing and lasts the life of the duct.
Standard sizes
The three common sizes are 32/26 mm, 40/33 mm and 50/42 mm (OD/ID). 40/33 mm remains the workhorse for city and highway OFC. 50/42 mm is preferred for high-capacity backbone routes where multiple sub-ducts may be pulled later.
Approvals and specifications
Look for conformance to TEC/GR/TX/CDS-008/03 (MAR-2011) and IS 14930 (Part 2). BSNL, RailTel and PGCIL projects mandate TEC compliance. Ask for the TEC approval letter and cross-verify on the TEC portal.
Key parameters
Working pressure (typically 12.5 bar), coefficient of friction (< 0.1), ripcord for easy slitting, and colour coding for network identification. Standard colours: orange, yellow, blue, green, red and black. Custom stripes and markings can be provided on order.
Procurement checklist
Verify raw material TC, silicone inner-layer test, hydrostatic pressure test at 20 bar for 1 hour, coefficient of friction test, and dimensional inspection per pack. Always insist on batch traceability with shift-wise records for a minimum of 5 years.
Handling and storage
Store coils on flat ground, avoid sharp edges during unloading, and protect the exposed ends with dust caps to prevent debris ingress before cable blowing. Sun exposure for more than 6 months requires UV-stabilised grades or shaded storage.
Why choose Almax PLB ducts
Almax PLB ducts conform to TEC/GR/TX/CDS-008 and IS 14930 (Part 2). Colour-coded HDPE with integrated silicone solid lubricant. Ripcord provided. Hydrostatic tested at 20 bar. Supplied to major telecom operators, BharatNet, BSNL, RailTel and private OFC network builders.
