Research Finds Cast Iron Water Pipes Can Temporarily Reseal

Recent research has uncovered some exciting news about cast iron pipes—they can actually ‘reseal' themselves, at least for a while!

This groundbreaking study, commissioned by UK Water Industry Research (UKWIR) and carried out by the University of Sheffield, dives deep into how cast iron infrastructure fails. The UK water sector is dealing with a vast network of grey cast iron (GCI) pipes, many of which date back to the interwar years. The newly released report, titled ‘Understanding how the deterioration of cast iron pipes evolves into leakage’, presents a validated model that helps predict fatigue strength, paving the way for smarter and more proactive leakage management.

One of the standout discoveries from this research is that micro-cracks in GCI pipes can actually “reseal” themselves when the internal pressure drops. This temporary fix gives utility companies a chance to focus on maintenance and plan interventions that minimize service interruptions.

Jeremy Heath, Innovation Manager at SES Water and UKWIR Programme Lead, shared his insights:

“The data showed that under certain dynamic loads, micro-cracks can close up if the pressure is reduced. The remaining strength of the cast iron effectively pulls the crack together, stopping the leak for a time.”

A Multidisciplinary Methodology

The research utilised a combination of numerical analysis and physical experimentation. Using high-speed photography and destructive laboratory testing, researchers investigated how fatigue cracking develops from artificial corrosion pits.

By analysing the stress response of cast iron during pressure transients—high-speed waves caused by valve closures or pump operations—the study identified previously misunderstood triggers for pipe fatigue and subsequent bursts.

Strategic Implications for Asset Management

The findings provide network operators with a high-resolution tool to assess the leakage failure risk of specific GCI assets. Key technical insights include:

Stress Concentration: Fatigue strength is heavily influenced by the geometry of corrosion pits and specific load combinations. Biaxial Stress Impact: 180° out-of-phase biaxial fatigue stresses can reduce the fatigue strength of pipes with uniform corrosion by up to 28%. Precision Replacement: By capturing pressure cycles accurately, utilities can transition to targeted, proactive asset replacement before the temporary “resealing” phase fails.

Advancing the ‘Zero Leakage' Ambition

This research supports UKWIR’s “Big Question”: How will we achieve zero leakage in a sustainable way by 2050? By managing water pressure to reduce maximum stress, utilities can prevent stable cracks from becoming unstable prematurely.

Mike Rose, Chief Executive of UKWIR, commented:

“This collaborative project perfectly illustrates our mission to provide a unified voice for the shared challenges facing water operators. This research provides vital intelligence on asset longevity and management, directly addressing our strategic goals regarding leakage reduction.”