Cement Lined Pipe

Designing cement lined pipe systems involves several considerations to ensure that the pipes meet the required performance standards and provide long-term reliability.  Here are some key design considerations for cement lined pipe systems.

• Material Selection  -  Choose the appropriate base pipe material (steel, ductile iron) based on the application's requirements, including factors like pressure, temperature, and the nature of the transported fluid.
• Pipe Diameter and Thickness  -  Determine the pipe diameter and wall thickness based on the flow rates, pressure, and other hydraulic requirements of the system.  Consider factors like pipe size transitions and fittings.
• Cement Mortar Thickness  -  Select the suitable thickness of the cement mortar lining based on the corrosiveness of the fluid and the expected service life.  Thicker linings provide better corrosion protection but can reduce the pipe's internal diameter.
• Pipe Joints  -  Choose appropriate joint types (flanged, threaded, welded) that are compatible with the application and ensure leak tight connections.  Properly sealing joints is crucial for preventing leaks and maintaining the integrity of the lining.
• Coatings and Linings for External Surface  -  Consider protective coatings or linings for the external surface of the pipe to prevent corrosion and extend the pipe's overall lifespan.  This is especially important for buried or submerged pipes.
• Support and Hanger Systems  -  Design a support and hanger system that can adequately bear the weight of the pipe and the fluid it carries.  Proper support prevents sagging, which can stress the lining.
• Expansion and Contraction  -  Account for thermal expansion and contraction in the design to prevent damage to the cement lining.   Expansion joints or flexible couplings may be required to accommodate temperature variations.
• Pipe Routing and Layout  -  Plan the pipe routing and layout carefully to minimize bends, elbows, and abrupt changes in direction, as these can affect fluid flow and increase wear on the lining.
• Installation and Quality Control  -  Ensure that the pipes are installed following industry standards and manufacturer recommendations.  Quality control during installation, including the inspection of the cement lining, is crucial to detect any defects or damage.
• Testing and Inspection  -  Conduct pressure testing and inspections to verify the integrity of the cement lining and the overall pipe system before putting it into service.
• Environmental Considerations  -  Consider the environmental conditions and potential exposure to chemicals or contaminants in the transported fluid when designing the lining material and thickness.
• Maintenance and Repair  -  Plan for periodic maintenance and inspection of the cement lined pipes to monitor their condition and address any issues promptly.

By taking these design considerations into account, engineers and designers can ensure that cement lined pipe systems are well suited for their intended applications, providing effective corrosion protection and reliable fluid transport.  Collaboration with experienced professionals and adherence to industry standards and guidelines are essential for successful design and implementation.

Cement Lined Pipe Fittings and Pipe Span Considerations

In order to put a branch connection on a cement lined pipe such as a Weld O'let or a Thread O'let, the pipe installer will need to penetrate the pipe and cement.  If the cement mortar is not repaired properly or if it becomes damaged, corrosive fluid can become trapped between the cement mortar and the pipe wall which will lead to corrosion.  The best way to engineer this out is to utilize bleed rings or reducing tees as much as possible.

Pipe that has been coated with cement has a smaller maximum span than carbon steel that has not.  The reason for this is when the pipe is deflecting, the bottom half of the pipe is in compression and the top, in tension.  Cement performs excellently in compression but extremely poorly in tension.  What will happen is the pipe concrete will either flake off or crack in such a way that corrosive fluid gets between the concrete and pipe wall which eventually lead to premature failure.