Dr.Steve Brogden
Die Draw Ltd, United Kingdom
12th November 2025, 14:00 GMT (15:00 CET, 09:00 US EST)
Overview
Cast/ductile iron, steel, PVC, GRP and concrete pipes can lose integrity over time by corrosion, tuberculation, joint leakage and low toughness. This may lead to fluid loss, reduced flow, and in the case of potable water, a reduction of water quality. The asset owner needs to make a decision on whether to decommission, replace or rehabilitate the pipes. Open-cut replacement is very costly and highly disruptive in urban areas. One rehabilitation solution is slip-lining with PE pipes, this however compromises flow capacity. An advanced solution is the swaged lining/die drawing process where a PE liner pipe can be engineered to act as a replacement within the original host pipe whilst maintaining or improving flow capacity.
Well-established methodologies and specifications exist for designing stand-alone pressure pipes using PE 100 and PE4710 materials for water and gas pipeline applications. Conservative fully structural liner pipe designs can utilize standard design methodologies with high safety factors, providing that this is both economically viable and that reduction in flow capacity is not prohibitive.
The objective of this presentation is to explain how advanced design principles can be used to optimize the design of polyethylene liner pipes for die drawing/swaged lining.
Thermoplastic pressure pipe design is grounded on the standard dimension ratio (SDR) or dimension ratio (DR). These ratios are simply the diameter divided by the wall thickness of the pipe, so SDR 11 is a very thick pipe with a high-pressure rating and SDR 41 is a thin pipe with a low-pressure rating. Semi-structural or interactive liners utilize the remaining strength of the aged host pipe. This enables a thin lower-pressure rated liner to be designed. The key design requirements for an interactive liner are gap bridging, hole spanning and collapse resistance, rather than hydrostatic strength. Using this approach, the design of very thin liners down to SDR/DR 41 or even thinner can be achieved, where an SDR/DR 11 may have been originally specified.
Recent advancements in temporary works design and sophisticated modelling using LiDAR enhance the predictability and ree ability to install very long continuous lengths. This leads to increased flow capacity, lower installation costs,liability of the current technology. The navigation of bends within the host pipe is a tangible benefit, coupled with th less disruption and environmental benefits such as significant reduction in carbon footprint. Two recent rehabilitation/replacement projects one for large diameter potable water and one for medium diameter wastewater will be used to demonstrate practical applications and lessons learned.
About Dr. Steven Brogden
Dr. Steve Brogden is a Polymer Engineer with 40 years of experience in materials technology, having specialized in thermoplastic pipes for over 35 years. Steve helped develop the UK Water Industry Specifications. His PhD led to the first guidance in the world for surge and fatigue design of PE and PVC pipes. Steve was the Technical Authority for swaged lining technology at Subsea7, being responsible for all liner design calculations globally. Steve has been Managing Director of Die Draw Ltd from its inception in 2018 to date, with the mission of re-introducing swaged lining/die drawing technology to the water and gas utility industries globally.