“Hari plaast” HDPE PIPES - A SOLUTION
Today one of the most puzzling problems for modern engineers is that of a selection of material construction in order to supply effectively drinking waters to the people. The basic properties material and its cost is one of the determining factors. Any cost of estimation should include the following
- Total material costs
- Labour costs to install
- Savings due to elimination of unscheduled shutdowns or maintenance cost
- Replacement costs
Hari Plaast Polyethylene pipes both High Density (HDPE) and Medium Density (MDPE) can carry water, waste water, slurries, chemicals, hazardous wastes, cables and compressed gases as well Polyethylene pipes have a long and successful service experience to the gas, oil, mining and industries. PE pipes have the lowest repair frequency per Kilometer of pipe per year compared with all other pipe materials used for urban water and gas distribution.
Hari Plaast PE Pipes are manufactured from High Density Polyethene-Pipe Grade Material PE-63, PE-80, PE-100 a most versatile material suitable for pipes. HDPE pipes are of low costs and high performance. The pipes are better substitute for costly Metallic pipes like CI, GI, AC, RCC & MS. HDPE Pipes are generally made black in colour by addition of Carbon Black to protect from ageing & degradation due to ultraviolet sunrays.
FEATURES AND BENEFITS
Economic Pipes and fittings are about 30% cheaper in material cost and 35% cheaper when installation cost are compared.
Light- weight Pipes are extremely light.
Highly flexible Easy installation on uneven contours/unleveled trenches.
Low friction Pipe walls are very smooth resulting in lower frictional losses. Do not permit any bacterial growth or algae.
Chemically inert Immune to corrosion due to any reasons with all chemicals from PH 0 to 14.
Weather resistant Pipes made from HDPE contain non toxic additives like carbon black which safeguards the use in open sunlight & do not pose any problem or stringency regarding their use for potable water supply.
Long life Designed to 50 years trouble free life in all kind of environ- ments.
FIELD OF APPLICATION
Effluent transport Long service life in handling effluents of all kinds.
Chemical transport Can resist corrosion by chemicals from PH 0 to 14. Can safely be used in hostile environments for acids, sludge, D.M.Water.
Gas transport High creep strength PE pipes ideal as gas carriers for Natural gas, Coal gas, LPG etc.
Slurry transport High abrasion resistance together with immune ness to corrosion is an advantage for handling slurry mixture of iron water, Boiler ash water & dredge slurry disposals.
Telecom ducts For use as underground optical fiber conduits.
Irrigation For micro and sprinkler irrigation systems.
|Melt Index||0.2 to 1.10 g/10 min|
|Tensile Strength at yield point||240 kg/cm²|
|Elongation at yield point||16%|
|Elongation at break||> 800%|
|Ball indentation hardness||480/420 kg/cm²|
|Shore hardness D||63|
|Notch Impact strength||9-12 kgcm/cm²|
|Coefficient of Linear thermal expansion (up to 80ºc)||1.5 to 2.0×10-4cm/cm0C|
|Heat conductivity up to 20ºc||0.37 K cal/mhc|
JOINING PROCEDURE OF HDPE PIPES
HDPE pipes can be permanently welded to give a strong and leak proof joint by fusion butt welding process as explained under:
- The pipe faces to be joined should be cut perpendicular to axis and aligned on the welding jacks to ensure close face to face contact
- The pipe faces to be to be thoroughly cleaned by using scrapper blade to remove any oily substances/dirt from the weld faces.
- The weld faces should be brought in contact with the heated mirror after ensuring correct temperature is achieved with help of thermo-chrome chalk. At correct temperature (2100C) the chalk marking will turn blue to black in three seconds.
- Gentle pressure on the pipe will fuse the face material in the form of rim.
- After sufficient (but not excess) fusion, mirror should be removed and pipe faces should be brought in contact under pressure till a fusion butt weld is formed.
- The weld should be cooled in ambient temperature under pressure.
- The weld pressure should be slowly applied to reach maximum of 1.2 kg/cm2 for proper welding.
Flow through HDPE Pipes
Q = 1002 X C X D2.63 X S0.54
Q = Rate of flow, M³ / hr.
D = Pipe Bore, ID in Mtrs.
C = Hazen/Williams constant for HDPE pipe = 150
S = Slop or Hydraulic gradient, mtr/mtr
With smoother wall thickness, HDPE pipe offers very low resistance to fluid flow (C factor = 150) compared to other conventional pipes. The rate of Frictional losses through HDPE pipes could be computed from the friction nomogram provided.
Hw = a/g X ∆ V, where,
Hw = surge pressure due to water hammer, M
a = Pressure wave velocity, Mtr/sec.
∆ V = change in flow velocity, Mtr/sec.
Following values of pressure wave velocity should be used for calculating water hammer.
for 2.0 kg/cm2 working Pr. Pipes 173 M/Sec
for 2.5 kg/cm2 working Pr. Pipes 199 M/Sec
for 4.0 kg/cm2 working Pr. Pipes 250 M/Sec
for 6.0 kg/cm2 working Pr. Pipes 305 M/Sec
for 10.0 kg/cm2 working Pr. Pipes 387 M/Sec
The sizing calculations should be checked to ensure that surge pressure does not exceed 1.5 times the working pressure classes.
HDPE BURIED PIPES
HDPE pipes can safely be buried underground in all types of soils but shall be protected by100 mm thick sand cushion when laid on to rocks or sharp edges. The permissible burial for all pressure classes of pipes for normal soil loads & under traffic are given below. It is however recommended to lay the pipe through RCC Hume pipes when crossing heavy traffic roads or Railway Tracks.