Valve Chamber Below Specification 22 Degree Elbow Bends Reinforcement
After a blowout in a valve chamber, a water company discovered that numerous 22 degree elbow joints in their 50-year-old cast iron pipe system were below specification, requiring urgent reinforcement to prevent similar incidents occurring in the future.
Case Study Overview
Site Valve chamber
Location Grimsby, UK
Pipe Type 450mm 22 degree cast iron elbow joints
Pressure 10 bar
Repair Type Pipe reinforcement
Products Liquid Metal Epoxy Coating, SylWrap HD Pipe Repair Bandage
The initial blowout occurred in a 50-year-old 450mm cast iron elbow bend. The water main pump from the reservoir to the treatment works stopped and the non-return valve closed, resulting in a pressure surge which peaked at 10bar from zero.
When the cast iron pieces were analysed, they showed no signs of corrosion along the crack lines. This led the water company to conclude that the blowout was most likely caused by the weakness of the original casting, which had a hardness of only 107.
To prevent similar incidents occurring in future, the water company needed to urgently carry out reinforcement to bring all remaining pipe elbow bends in the valve chamber up to specification.
Each elbow joint required reinforcement over a 350mm section between flanges. The application needed to withstand 8 bar pressure as standard with fluctuations up to 10 bar, as had caused the original blowout.
Two stages of the Sylmasta Pipe Repair System were used to strengthen the pipework. After cleaning each elbow, Liquid Metal Epoxy Coating was brush applied across the entire bend.
Liquid Metal sets to provide a smooth, metallic, hard-wearing layer over pipework. It protects against corrosion and importantly for the reinforcing of high-pressure pipework, creates a PCC-2 compliant load-transfer layer when used in conjunction with SylWrap HD Pipe Repair Bandage.
10 layers of SylWrap HD were wrapped over the top of the coating of Liquid Metal. SylWrap HD is a composite repair wrap with a water activated resin which sets rock hard in minutes, providing an impact resistant protective sleeve around the elbow bends which greatly increased strength and pressure resistance.
It took between 2 and 3 hours to reinforce each elbow joint and there was no need to shut off the water supply, enabling the site to remain fully operational.
Strengthening the elbow bends offered a significant cost saving compared to replacing the below specification pipework.
Following the repair, the strategic water operations manager of the water company said: “The wrapping materials have proved central to our project in securing the structural condition of some 22 degree bends found to be in weak condition.”
“The early success of the project in Grimsby has seen it already adopted by other sites in our network, with Hartlepool also happy with it as a preventative measure and more to follow.”
Epoxy coating brush applied for corrosion protection and pipeline strengthening
SylWrap HD Bandage
Water-activated wrap sets rock hard to reinforce, protect and strengthen pipework
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