Double-wall corrugated pipe is a corrugated outer wall is hollow, smooth wall of the new pipe, compared with other types of pipe the same size with strength, with a material saving, light weight, high rigidity, excellent bending properties, high impact, high compressive strength, construction convenient. Has been widely used as buried pipes, underground cables, pipes, etc., for a range has replaced the traditional cast iron pipes, cement pipes, plastic pipes and ordinary winding bellows. Currently wall corrugated pipe main varieties are PVC (pvc) and high density polyethylene (HDPE) two kinds. The HDPE double wall corrugated pipe has its corrosion resistance, easy to scale the surface, friction is small, excellent weatherability, good processing performance and long life (typically about 50 years in the ground, in the air for about 25 years), etc. Features and more widely used. However, currently in use by the impact of buried HDPE double wall corrugated pipe in particular is the biggest problem of large diameter HDPE double wall corrugated pipe ring stiffness is low.
Because underground drainage and sewerage main load bearing plastic pipe from the outside of the pipe, so the pipe ring stiffness is an important indicator. Ring stiffness is higher, the higher the pipe to withstand external load capacity; on the contrary, the smaller the pipe ring stiffness, then lower the pipe's ability to withstand external loads. According to ISO 9969-1994, the definition of double-wall corrugated pipe ring stiffness is:
S = EI/D3 (where: S-ring stiffness, kPa; E-elastic modulus of the material, GPa; I-moment of inertia of the cross section of pipe structure, m4/m; D-the average diameter of the pipe, m)
Seen from the definition of ring stiffness, when the pipe diameter is constant, and the ring stiffness is the modulus of elasticity and pipe structural section moment of inertia is proportional to the material, and the pipe cross-section moment of inertia of the structure and the structure of the double wall corrugated pipe design of the waveform . Usually appropriate to increase the height of the wall thickness of the pipe wall corrugated pipe or heightening can significantly improve the moment of inertia. Elastic modulus of the material itself is the nature and properties of the added fillers and additives, resins related.
And the choice of high modulus resin or other high modulus resin modification, or to increase the thickness of the pipe wall corrugated pipe ring stiffness increase is undoubtedly going to increase the cost of production tubing. Improved design of double-wall corrugated bellows, can be improved to some extent, the pipe ring stiffness, but there is a limit, and easy to make complex waveform pipe internal stress is increased, is difficult to mold. So by adding inorganic fillers to improve pipe ring stiffness is undoubtedly the easiest and most effective way, while also reducing costs.
Ultra-fine glass bubble is a high strength, high hardness inert spherical particles, the main component of SiO2, Na2O, CaO, Al2O3, etc., it has two sources: one is prepared by melting the glass; the other is from Separated ash derived. The latter has a small particle size (1 ~ 7μm), low density, low price.
Because of fine glass bubble with the above characteristics, its organic process, and make the HDPE blends prepared high ring stiffness, high impact, low cost of HDPE double wall corrugated pipe.