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FEATURES
Some ice in your pipe
By
Tanya Olckers and Andrew Matake , managing director of Yunik Engineering
Pipe-freezing refers to the process of applying an external refrigerant or cryogen to freeze fluid contained in a pipe . It is a relatively safe and costeffective procedure for temporary piping system isolation .
Freeze sealing is most often used to isolate a section of a piping system where no other ready means of isolation , such as valving , is available . In many cases , pipe-freezing is performed specifically to perform maintenance or repairs to a system isolation valve ( point of isolation ). Freeze sealing can also be used to isolate a section of a piping system for hydrostatic testing .
Pipe-freezing involves the use of a cryogen ( freezing agent ) in the controlled formation of a solid ice plug within the pipeline . Once the freeze is achieved the plug has the capability to withstand high differential pressures and provides a reliable isolation that is extremely effective , allowing alterations to be completed without a full drain down .
The earliest recorded patents for freeze sealing technology date back to 1904 , but the widespread use of freeze sealing for repair or modification work began with the US Navy during the 1940s . The Navy ’ s technical manual , describing the methods and uses of freeze sealing , has been the classic reference for years . It has often been the only source for decisions made regarding freeze sealing . The first recorded uses of freeze sealing technology by the US nuclear power industry were in 1978 . However , the Canadian nuclear power industry was using freeze sealing technology as early as 1968 .
“ Pipe freezing is a little bit like a tourniquet ,” says Andre Wessels , technical lead with Machine Cutting Services ( MCS ). “ So , if you have a complex plumbing system with lots of branch pipes , and you have a leak in one of the branch pipes , but you don ’ t want to isolate the whole system , or it ’ s not possible to isolate the whole system , you then freeze the water in the pipe upstream of the leak . You therefore form a plug of ice inside the pipe , and that plug of ice prevents the water from going to where the leak is .”
One thing to bear in mind , according to Wessels , is that electric pipe freezing machinery needs a consistent and constant supply of power ( or cryogenic substance ) in order to maintain the freeze . It is important to keep this in mind , especially in areas experiencing a number of power outages . As soon as the needed electricity is turned off , the machine stops functioning and the risk of the ice melting before the repair can be completed is high . This doesn ’ t apply however to machines using cryogenic material because they do not use electricity .
Pipe freezing machinery and technology are used in instances where one is not able to switch off the main water supply line for repairs . “ Sometimes the plumber can ’ t find the line , or the main water valve is damaged ,” says Adler Teubes , managing director of Rothenberger South Africa , “ The other thing to consider is the application . For example , hospitals can ’ t have the entire building ’ s water supply shut off during repairs .”
The clamps of the pipe freezing machine are placed on one or both ends of area where you want to repair , stopping inflow of water from both directions . The machine works with refrigerant gases to freeze pipe contents . The freezing will not work on fluids that have been treated with antifreeze . Depending on ambient temperature , water temperature , and the flow rate of water in the pipe , it can take between 5 and 20 min or even much longer ( hours ) to freeze a pipe , depending on pipe diameter and material to freeze a pipe . Work can be done on the area and once the clamps are disconnected , the water that was frozen begins to melt .
Plumbers are advised to take special care of any freezing machinery they may have . “ If you are transporting the machine , you need to make sure it ’ s in an upright and stable position ,” advises Wessels , “ You want to protect your freezing head from any mechanical damage .”
Image supplied by Machine Cutting Services
Pipe section is frozen .
Precautions :
• Leather insulated gloves should be worn when handling the clamps as there is a risk of frostbite . Do not handle the frozen area or clamps with bare hands .
• Pipe freezing works best on metal pipes .
• Take special care when working on thin-walled copper pipes as there is a risk of the pipes bursting if the metal is unable to handle the cold .
• Avoid using this method on multilayer PEX pipe , and other plastic pipes , as this material inhibits cold and may fail when exposed to extremely low temperatures .
• Constant electrical power is needed to keep the machine working and the freeze in place , if one is using a device that requires electricity .
www . plumbingafrica . co . za @ plumbingonline @ plumbingonline @ PlumbingAfricaOnline February 2025 Volume 30 I Number 12