Cement-lined pipe is made by applying cement mortar to the inside of the steel pipe.
The technology involves spraying cement lined steel pipe for sewage transport to protect them. The mortar adheres to the pipe wall, forming an 8-13mm layer, blocking steel from the medium. This cost-effective, pollution-free method emphasizes cement mortar lining technology.
The combination of cement, sand, and water is called cement mortar. The commonly referred to 1:3 cement mortar is a mixture of 1 part cement and 3 parts sand. In fact, the water component is ignored. The ratio is generally around 0.6, which should be the purpose of 0.6:1:3 cement mortar.
In construction projects, cement mortar serves two main purposes: one is for foundation and wall masonry, acting as an adhesive for block masonry materials such as rubble and red bricks; the other is for indoor and outdoor plastering. When cement mortar is used, workers often add additives such as microfoaming agent, waterproof powder, etc., to improve its workability and viscosity.
Additionally, when stones are added to cement mortar in proportion, it transforms into concrete. The graded strength of cement mortar refers to a value in the overall distribution of compressive strength measured using standard test methods for cube specimens made and maintained according to standard methods at 28 days of age.The performance of steel components under the action of external forces still has a certain impact.
Cement mortar lining is not only a simple barrier in terms of physical properties, but also protects pipelines through the chemical properties of cement mortar lining. The mortar layer is combined with the pipe to form a passivation area with a pH value of up to 12 on the pipe wall.
As water passes through, it penetrates into the cement mortar, which is rich in alkaline components, rendering the water non-corrosive when it reaches the pipe wall. The lining is then applied once or multiple times on the cleaned inner wall of the pipe according to the design thickness requirements. After a certain period of maintenance, a passivation zone with a pH value of up to 12 is formed. The inner lining of the high-strength circular shell tightly integrates with the inner wall of the tube.
The cement lined pipe for sewage pipes is pollution-free, easy to construct, and cost-effective. Cement mortar shrinks and adheres to the inner steel pipe wall, creating friction. The uneven pipe wall generates squeezing force due to mechanical bite. Early cracks in cement mortar linings result from volume shrinkage in air. Adding additives and adjusting temperature and humidity during curing reduces crack occurrence.
The cement lined pipe is made of two different materials. How strong is the bond between the mortar and the pipe? Particularly, will the anti-corrosion layer inside the steel pipe detach due to external forces like transportation and installation? In other words, what is its mechanical strength?
Experimental data confirms its mechanical strength. When the steel pipe is deformed and flattened by external pressure, “hair-like” cracks may appear in the mortar, but it’s challenging to peel the mortar from the pipe wall. For instance, on a DN800 mm steel pipe with a wall thickness of 7.1 mm, a one-meter-long section lined with an 11 mm thick mortar coating was cut. When the flattening amount reaches 7-8 mm, “hair-like” cracks become visible. As the flattening amount increases to 50 mm, the cracks gradually extend to the entire pipe section at the edge.
Experimental results show that “hair-like” cracks occur when the flattening amount is 1% of the pipe diameter. When the flattening amount is 6-9%, the mortar coating It begins to crack and peels off when it reaches 30% of the pipe diameter. This is never allowed to happen during construction.
According to measurements, the flatness on the DN1100 cement lined pipe is 15 mm, and on the DN1800 cement lined pipe it is 21 mm. It can be seen that as the pipe diameter increases, the flattening amount of cracks also increases. The friction coefficient of cement mortar lined steel pipes has increased from 0.012 to 0.019 or even above 0.02, which directly affects the water quality of the water plant and the energy consumption of water supply.
Specifications and theoretical weight of cement mortar lined steel pipe. Cement mortar usually sits on the inner wall of spiral steel pipe. People can calculate the weight of spiral steel pipes but generally do not understand the weight of cement mortar lining. When shipping steel pipes, the tonnage is generally required, so the weight of the cement mortar is very important.
The following is the calculation method of the weight of cement motar. The weight of cement mortar is based on the weight of the steel pipe. It is actually very simple to calculate the weight of the steel pipe. The weight of the cement mortar is 1/3 of the weight of the steel pipe. It must be remembered.
Cement mortar lined steel pipe is an anti-corrosion steel pipe that has attracted much attention in sewage pipelines. Cement mortar lined steel pipe has the above advantages. Its anti-corrosion function and economy are recognized by more and more engineering and technical departments. Many large and medium-sized cities use cement mortar as a The main points of corrosion protection in water supply metal pipes.
Construction steps Cement mortar lining spiral steel pipes is a common method of lining drinking water pipes. Since the quality of the surface anti-corrosion directly affects the service life of the steel pipes, great attention must be paid when lining cement mortar to not only prevent damage to the spiral steel pipes. Damage, but also to ensure the quality of the anti-corrosion.
1. Use hand tools to remove rust, and use an electric rotating wire brush to remove loose scale, floating rust and other debris on the metal surface;
2. There is no visible grease and dirt on the surface of the steel after rust removal, and there is no loose scale, rust and other attachments. The quality grade of the steel surface after rust removal is St3.
3. Once the steel surface is rust-free, it should be reported in time. After inspection and confirmation, the next process can be carried out only after passing the inspection by the inspector.
4. Primer and topcoat before wrapping with glass cloth
5. The anti-corrosion epoxy coal pitch paint is applied by brushing according to the site conditions.
6. Apply primer and topcoat after the steel is derusted and inspected. When painting, try to leave the weld position of the steel assembly as much as possible. The reserved length is about 150mm to avoid difficulty in clearing the roots during welding and affecting the welding quality.
When purchasing cement mortar lined steel pipe, prioritizing cost-effectiveness over price alone is crucial. Quality steel pipes ensure optimal usability. Bulk purchases require comparing quotes online, typically concentrated among reputable brands. While tempted by low prices, prioritize anti-corrosion performance and avoid high-cost maintenance or replacements later on, affecting long-term efficiency.
Cangzhou DoubleDragon Steel Pipe Co., Ltd specializes in the production of lining and coating pipes and spiral welded pipe, including cement lined spiral steel pipe. The factory has been established for 30 years, with production diameters of 8-140 inches and wall thicknesses of 6-26mm. Friends from all over the world are welcome to exchange and consult.
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