FEATURES 23
Pipe-freezing methods The basic method for freeze sealing can be classified based on the type of operation or type of refrigerant used . Types of operation include :
• Manual feeding of refrigerant
• Remote manual control of the freeze seal process
• Remote automatic freeze seal method
Image supplied by Rothenberger
Types of refrigerants commonly used include :
• Liquid nitrogen
• Dry ice ( CO2 )
• Freon
• A mixture of any of the above refrigerants with alcohol or glycol .
Some freeze sealing methods use mixtures of the primary refrigerants along with alcohol or glycol . In these cases , use the precautions for the most
Pipe freezing in action severe component of the mixture or , preferably , precautions for all components used if they do not conflict .
“ It ’ s best to work with rubber gloves ,” says Teubes , “ The clamps can get extremely cold and touching them with bare hands can result in injury like frost bite .”
Where would you use pipe-freezing Three routine applications for freeze sealing are to :
• Enhance maintenance capabilities during shutdown or outage periods by providing pipe isolations
• Provide blocking in lines where valves or stops are not placed to replace faulty valves or to carry out pipe modifications or extensions
• Eliminate the necessity of taking a full system out of service during plant operation , which might cause a limiting condition for operation
Pipe freezing services can be used to perform any of the following routine system modifications
• Valve installations
• Pipe section replacement
• Equipment isolation
• Pipe branch terminations
• Pipe relocations
What are the benefits of using pipe-freezing Pipe freezing is widely acknowledged as a safe , reliable and highly costeffective method of temporary pipeline isolation and offers several major benefits some of which are : -
• No need to drain down systems , avoiding costly and time-consuming venting procedures
• No need to arrange for the bulk transfer / storage of fluids
• Cuts losses of expensive liquids , such as treated water and system inhibitors , as ‘ break-in ’ can be performed without incurring the costs and down-time of a complete system drain down
• Overcomes the problems of handling hazardous materials and enhances safety when working on lines containing contaminated or volatile liquids
• Avoids a complete system or related systems from shutting down by isolating selected sections for maintenance purposes . This is a cost cutting exercise as well as a form of on-line maintenance tool
Common pipe-freezing area applications
• Cooling water
• Fire protection systems
• Process systems
• Fuel oil lines
• Sludge lines
• Hydraulic control lines
• Domestic / utility systems
• Hydrocarbon risers
• Water injection lines
• Heat exchanger lines
• Heating services
• Chilled water systems
Common pipe contents
• Water
• Acids
• Coolants
• Paints
• Alcohols
• Oils
• Liquid food product
• Various chemicals
• Sewage
Typical pipe materials
• Carbon steel
• Nickel alloy
• Copper-based alloys
• Aluminium alloys
• Stainless steel
• Plastic Clamps are used for the freezing process .
Risks of using pipe-freezing and precautions
• Nitrogen may cause asphyxiation in confined spaces
• When done without due diligence , it may result in pipe bursts and flooding
• Not applicable to moving fluids
• Relies on proper technical assessment of pipework system before embarking on pipe-freezing otherwise wrong assessments may result in pipe failures and irreparable damages
Image supplied by Rothenberger
February 2025 Volume 30 I Number 12 www . plumbingafrica . co . za