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Drainage Flexible Joint Cast Iron Pipe (A Straight Pipe)

Summary information
Product parameters

The A-style flexible interface cast iron pipes and fittings are produced based on the GB/T12772-2008 standard for “flexible interface cast iron drainage pipes, fittings and accessories”. Flexible flanges and sealing gaskets are used for the connection in installations, featured by good seismic performance, excellent airtightness, simple construction, easy maintenance, and reliable use. The company offers more than 190 varieties and specifications of cast iron pipe fittings and ancillary rubber seal rings with DN50-DN200 apertures.

With the rapid development of China's economic construction, and the improvement of people's living standards, the requirements for residential buildings are increasingly higher. While being concerned about the area, size, and orientation of housings, people are also increasingly concerned about the design of the essential parts – kitchens and bathrooms.

Compared with traditional handmade sand casting socket pipes and PVC plastic pipes, flexible interface machine made cast iron pipes have unparalleled advantages. The latter has been used in the United States, Japan and other countries as building drainage installation materials. Due to historical and economic reasons, our country did not eliminate sand molding cast iron pipes and restrict the use of PVC pipes in high-rise buildings until 2000. On November 1, 1999, the State Quality and Technical Supervision Bureau formulated and promulgated the GB/T12772-1999 “flexible interface cast iron drainage pipes and fittings” standard with reference to the CISPI-301-1990 standard of the Cast Iron Pipes Association of the United States. On January 14, 2003, the Ministry of Construction released the CJ / T 177-2002 “building drainage clamp cast iron pipes and fittings” standard and the CJ / T 178-2003 “flexible interface socket type cast iron pipes and fittings for building drainage” standard in accordance with the ISO6594: 1995 “cast iron drainage pipes and fittings” standard. According to the development of cast iron pipes since 1999, on September 11, 2008, the State Administration of Quality Supervision, Inspection and Quarantine and the National Standardization Administration Committee developed and issued the GB/T12772-2008 “drainage purposed flexible interface cast iron pipes, fittings and accessories” based on the original GB/T12772-1999 standard. Thus, we can see that it is already inevitable for the new machine-made flexible interface cast iron drainage pipes to replace the traditional pipes.

Due to such advantages of the machine-made flexible interface cast iron drainage pipes such as high strength, corrosion resistance, flame resistance, low noise, long life, non-deformation, shock resistance, easy installation and maintenance, and nice appearance, they have become the mainstream building drainage systems, being widely applied in some upscale public buildings and residential quarters, and enjoying good prospects for development.

Flexible cast iron pipes are molded with HT150 gray cast iron through high-speed centrifugal casting. The machine-made flexible interface cast iron drainage pipes and fittings being universally used in the world are divided into two categories: either with or without sockets. The new standards issued GB/T12772-2008 “flexible interface cast iron drainage pipes, fittings and accessories” is mainly applied to W and W1 socket-free flexible pipe hoop type and A and B-type socket flange connected flexible interface cast iron drainage pipes and fittings, which are named W, W1, A and B types. The advantages of W and W1 types are small footprint, easy installation and maintenance; the advantages of the A type is high connection strength and easy installation; the advantages of the B type is high connection strength and easy installation, and can be easily connected with the W and W1-type straight socket-free pipes.


Machine-made flexible interface cast iron drainage pipes are rugged, featured by excellent durability, heat resistance, silent function, and shock resistance


1. High material strength The flexible cast iron drainage pipe has good mechanical properties. Its tensile strength stipulated according to the standard is more than 150Mpa, while the tensile strength stipulated according to the standard of a high-class UPVC pipe is only 43Mpa. Its impact resistance and abrasion resistance are superior to those of the UPVC pipe.

2. Durability The flexible cast iron drainage pipe formed by high-speed centrifugal casting features compact structure, high strength, good corrosion resistance, abrasion resistance and ageing resistance and long service life.

Pipe type

Cast iron drainage pipe

Galvanized steel pipe

Stainless steel pipe used in indoor


UPVC tube

Durability grade






Service life






3. Heat resistance The flexible cast iron drainage pipe has good heat resistance and thermal deformation resistance, and can resist high temperature of thousands of degrees centigrade. A sealing rubber ring for pipeline connection can be normally used without damage under 70℃ continuous discharge and 120℃ intermittent discharge conditions. The UPVC pipe has low heat resistance and using temperature of 0-60℃ generally. The stretching deformation of the heated cast iron pipe is only one seventh of that of a PVC plastic pipe. The flexible cast iron drainage pipe is applicable for high-rise building drainage pipelines.  

Pipe type

Cast iron pipe

UPVC tube

Coefficient of linear expansion (/ ℃)

1 x 10-5

7 x 10-5

4. Silence The flexible cast iron drainage pipe can absorb vibration and noise generated by water flow due to the internal flake graphite structure of gray cast iron. Its wall is thicker than that of the UPVC pipe, and it has a good sound-proof effect. Pipes and pipe fittings are connected through a flexible rubber sealing ring to effectively weaken transfer of vibration and noise, so the flexible cast iron drainage pipe has good sound-proof and silent effects. The drainage noise of the flexible cast iron drainage pipe is 10db lower than that of the UPVC drainage pipe, so it can be comparable to the best silent pipe, φ110mm cast iron pipe and UPVC pipe, in terms of noise level.

Cast iron drainage pipe

UPVC tube

Noise DB



* test place is located at one meter distance pipeline, drainage volume was 2.7L/S, the environmental noise 42db

5. Earthquake resistance A building certainly swings and generates inter-story axial displacement and horizontal displacement under the action of a horizontal wind load and an earthquake load. The flexible cast iron drainage pipe can meet the requirements of large horizontal and axial displacement deformation of the building due to the connection of a flexible rubber sealing ring or flexible stainless steel hoop. Water starts leaking when the deflection value of a rigid joint pipe is ±1.2mm according to pipeline lateral earthquake-proof deflection simulation test, while the pipe does not seep or leak when the lateral vibration deflection value of the flexible joint cast iron pipe reaches ±(31.5-43.5)mm, and axial displacement reaches ±35mm. The flexible joint drainage cast iron pipe is safe when used for nine degree earthquake-proof fortification according to Chinese related pipeline earthquake-proof specifications.

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