According to the materials, cast iron pipe can be divided into: gray cast iron pipe, Ductile Cast Iron Pipe and high silicon iron pipe. Cast iron pipe
is used for water supply, drainage and gas pipeline projects. In the middle and low pressure pipe network, cast iron pipe with safe and reliable operation, low damage rate, fast and convenient construction and maintenance, excellent anti-corrosion performance, etc..
The connection mold of cast iron pipe
Cast iron pipe made the pipe by casting molding. Cast iron pipe is used for water supply, drainage and gas transmission pipeline; it includes the cast iron pipe and pipe fittings. The labor intensity is small. According to the different casting methods, it is divided into continuous cast iron pipe and the centrifugal cast iron pipe, furthermore, the centrifugal cast iron pipe is divided into sand mold and metal mold. According to the different materials, it is divided into gray cast iron pipe and ductile cast iron pipe. According to the different forms of interface, it is divided into flexible interface, flange interface, self anchored interface and rigid interface etc.. Among them, flexible cast iron pipe is sealed with rubber ring; flange interface cast iron pipe is fixed with flange and sealed with rubber flange gasket; rigid interface is generally made of cast iron pipe bearing a large opening, straight after the insertion, sealed with cement, this technology has been basically eliminated.
The connection between the cast iron pipe and the pipe adopt the socket type or the flange disc type interface. According to the function, it can be divided into flexible interface and rigid interface. Due to the flexible interface is sealed by rubber ring, and it allows a certain degree of rotation and displacement, and thus it has a good seismic resistance and sealing performance. The installation of the flexible interface type is simpler and easier than the rigid interface type, the casting method between them is different, and the former labor intensity is small.
The characteristics of cast iron pipe:
1.The cast iron pipe is characterized with both ductility of steel, high strength and pressure resistance, and the corrosion resistance of gray cast iron;
2. The elongation can reach more than 10%, the tensile strength is greater than 420 MPa, the pressure value of it up to 4 MPa or more, especially in line with high pressure, high resistance to deformation of the requirements of the water supply, gas, oil pipeline system;
3. The stable chemical performance of the cast iron pipe supplemented with zinc spraying, painting and other anti-corrosion measures enable it to have excellent corrosion resistance, and service life of it up to more than a hundred years.
4. The installation and construction is simple and quick. The project cost is economical;
5. High reliability: cast iron pipe has high bearing capacity and a certain extension rate. The adoption of the flexible interface enables the diversion of the axial offset 3 to 5 degrees will not produce medium penetration and leakage. The cast iron pipe has the ability of strong anti-seismic and anti foundation subsidence.
Installation technique of the cast iron pipe:
1. During the construction in summer, the soil can be properly covered in the interface.
2. Trench backfill should be tamped, if the pipeline across the road, to avoid crushing tube, can be backfilled with coarse sand to the top of the pipe.
3. If the condition is not allowed pressure test, the air pressure test is advisable.
4. In hot summer, lubricating oil should be used with vegetable oil; in cold winter, rubber ring can be used with hot water to preheat, in order to reduce the hardness and accelerate installation.
5. Tee and elbow must be done concrete pier.
6. Interface occurred drip in the construction sometimes. To avoid this phenomenon, in (during) the installation, it should strictly comply with the standard construction. It is necessary to guarantee that each tube is installed in right place. For large diameter pipeline, workers need to check each interface apron.
7. To facilitate the installation, people can use water to soak the rubber ring first. Pipe installation if it require by the turn, and it can not meet the requirement by using its’ own by the turn angle. According to the by the turn angle, after calculations, beveling the pipe socket after cutting mouth, which can increase by the turn angle, and ensure the safety in using.
Suggestions for selecting cast iron pipe
1. The selection of the nodular cast iron pipe should be according to the specific circumstances of laying to select interface type of straight pipe and accessories.
2. The rubber ring is recommended for EPDM.
3. Coating selection: According to the internal and external conditions to select the appropriate coating. The existing internal coating is new products of ductile cast iron, such as epoxy resin, polyurethane coating inside and outside, PE film coating. consumers should deeply understand its performance when purchasing it.