Cement Lined Pipe Size
|
| Nominal Pipe Size (in) |
AWWA C205 Mortar Thickness (in) |
Maximum Span (ft) |
| 2 |
0.25 |
21 |
| 2-1/2 |
0.25 |
26 |
| 3 |
0.25 |
26 |
| 4 |
0.25 |
26 |
| 6 |
0.25 |
34 |
| 8 |
0.25 |
39 |
| 10 |
0.25 |
40 |
| 12 |
0.3125 |
42 |
| 14 |
0.3125 |
43 |
| 16 |
0.3125 |
45 |
| 18 |
0.3125 |
48 |
| 20 |
0.3125 |
48 |
| 22 |
0.3125 |
50 |
| 24 |
0.375 |
50 |
Cement lined pipe is most commonly constructed of ductile iron, cast iron, or steel, that has an internal lining composed of cement mortar. The lining is applied to the interior surface of the pipe to provide corrosion protection and to improve hydraulic performance. Cement mortar linings have been widely used in potable water, wastewater, and other water transmission and distribution systems.
The primary function of the cement mortar lining is corrosion control. When ferrous pipe materials are exposed to water and dissolved oxygen, electrochemical corrosion can occur. A cement mortar lining forms a physical barrier between the conveyed fluid and the metallic substrate. In addition, the high alkalinity (high pH) of hydrated cement promotes the formation of a passive film on the iron surface, which further inhibits corrosion. This combination of barrier protection and alkaline passivation is well documented in waterworks practice.
Application methods are standardized. For ductile iron pipe, cement mortar lining is typically centrifugally applied at the manufacturing plant, producing a dense, uniform layer bonded to the pipe wall. Thickness requirements are specified by nominal pipe diameter in the applicable standards. For steel pipe, linings may be shop-applied by centrifugal casting or hand troweling, or field-applied at joints. Curing is controlled to ensure proper hydration and bond development.
Cement Lined Pipe Benefits
Corrosion Protection - The cement lining acts as a barrier between the interior of the pipe and the corrosive elements in the fluid or gas it carries. This helps extend the lifespan of the pipe and reduces the need for frequent maintenance or replacement.
Smooth Interior Surface - The cement lining creates a smooth and uniform interior surface, which helps to improve the flow of fluids and reduce friction within the pipe. This can lead to
energy savings and increased
efficiency in fluid transport.
Versatility - Cement lined pipes can be used for a wide range of applications, including potable water distribution, wastewater transport, and the conveyance of various chemicals and slurries.
Longevity - Properly installed and maintained cement lined pipes can have a long service life, making them a cost effective choice for many infrastructure projects.
Compatibility - Cement lining is compatible with a variety of materials commonly used in pipe construction, such as steel and ductile iron.
It's important to note that cement lining is just one of several lining materials available for pipes, and the choice of lining material depends on factors such as the specific application, the type of fluid or gas being transported, and environmental conditions. Proper installation and maintenance are crucial to ensure the effectiveness and durability of cement lined pipe.
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.
Mortar Thicknesses
The thickness of the cement mortar lining in cement lined pipes can vary depending on several factors, including the specific application, the corrosiveness of the fluid being transported, industry standards, and engineering considerations. The selection of cement mortar lining thickness in pipes should be a carefully considered decision that takes into account the specific needs of the project, including corrosion resistance, hydraulic performance, industry standards, and cost considerations. Engineers and designers should work closely with manufacturers and refer to relevant standards and guidelines to make informed decisions regarding lining thickness. Due to the fragility of the cement lined coating, it is recommended that the pipe is handled as delicately as possible. This includes the use of rubber covered hooks or other equipment that prevents the damage of the lining.
Mortar thicknesses often vary per manufacturer. Typical mortar thicknesses are: \(\;\frac{1}{4}",\;\frac{5}{16}",\;\frac{3}{8}",\;\frac{1}{2}",\;\frac{5}{16}",\;\frac{3}{4}",\;1" \)
Cement Lined Pipe Standards
- ASTM Standards
- ASTM C541 / C541M - Standard Specification for Linings for Asbestos-Cement Pipe
