Why KiTEC Pipe?
Water supply piping is one of the most important constituents of the building. Various piping materials are used for building water supply piping. These can be categorized as- I. Metal pipes and II. Plastic pipes. Following piping materials are used in these categories:
- Metal Pipes : GI Pipes, Copper Pipes.
- Plastic Pipes : PVC pipes, CPVC pipes, PE pipes, XLPE pipes, Polybutylene Pipe
- Composite pipes : Metal & Plastic combination is the new addition
Metal and plastic pipes have their own advantages. However, there are some inherent disadvantages associated with both types of the pipes. Hence the innovation of Composite pipes – that eliminates all the disadvantages of both the materials and takes advantage and strengths of both the materials.
Given below are various properties and performance requirements for sound plumbing. The performance characteristics for various associated factors are as follows:
1. Effect of water Quality
The pipes must be suitable for use with hard as well as soft water.
Metal pipes are generally susceptible to corrosion. Copper pipes are also prone to corrosion when used for soft acidic water. In case of hard water, scale deposition in GI pipes leads to unsatisfactory flow over the life span of the pipe. In many cases, the pipe has to be replaced frequently.
Plastic pipes have no effect of water quality.
Composite pipes, with inner and outer plastic (PE) layer, have no effect of water quality and are suitable for hard as well as soft water.
2. Health Criterion
The effect of water on the piping material is a major factor that many times goes neglected. The basic piping material, many a times, has some effect or their on the pipe. This can be tested for following properties:
- Taste of water.
- Appearance of water
- Growth of aquatic micro-organisms.
- Extraction of substances that may be of concern to public health.
Because of corrosion, metal pipes, particularly GI pipes, cannot be considered good on this ground. The lead content in GI further reduces the suitability for this application. In case of copper pipes solder joints and fluxes have lead content that causes worries to scientists.
Plastic pipes as well as composite pipes do not have any adverse effect of water.
3. Thermal Strength properties
The piping material, ideally, should not have any limitations when used for hot water.
Metal pipes, GI as well as copper, do not have any effect when used for hot water.
In plastic pipes, the rated pressure of pipe reduces drastically with increase in design life span at specified operating temperature. At the same time, the life of the pipe reduces drastically with the increase in operating temperature.
Thus PVC pipes are not recommended for hot water. PE pipes also loose considerable strength when used for hot water. CPVC pipes have better strength at elevated temperature amongst all plastic pipes.
Composite pipes have these properties balanced to satisfying levels.
4. UV Resistance
Effect of UV radiation is a major criterion particularly in case of plastic pipes. Metal pipes do not have any effect of UV radiation.
PVC pipes are not supposed to be used for external piping due to the effect of UV rays.
CPVC contains TiO2, which is not as good a UV stabilizer as carbon black. Hence, these pipes cannot be recommended for outdoor installations. Painting of pipes for UV resistance is recommended but cannot be considered as fool proof method for UV stabilization over a long, maintenance free life span.
However, PE as well as Composite pipes does not have any effect of UV radiation if a proper UV stabilizer, such as carbon black is used. With the use of carbon black, PE pipes as well as composite pipes can be safely used for external installations.
5. Thermal Expansion
High coefficient of thermal expansion leads to thermal stresses. These stresses lead to unwanted stresses on supports provided for the piping. Thus, in case of concealed piping,
thermal stresses may lead to cracking of the tiles if the pipes with high thermal expansion coefficient are used. In case of hot water, the amount of thermal stresses developed is further higher.
Metal pipes, copper as well as GI have very low coefficient of thermal expansion. CPVC, HDPE, PVC pipes are having high coefficient of thermal expansion.
Composite pipes, because of aluminium layer, have coefficient of thermal expansion approximately equivalent to copper pipes.
Comparative values for thermal expansion for CPVC, HDPE and Composite pipes are as follows:
- Coefficient of Linear Expansion:
- Composite pipes: 1.3 x 10-5 meter/meter / oF
- CPVC: 3.4 x 10-5 meter./meter/ oF
- HDPE: 12 x 10-5 meter./meter/ oF
Composite pipe has a low coefficient of linear expansion, similar to copper tubing, and is far superior to alternate plastic pipe such as CPVC/HDPE/PP. This eliminates the need of installation "offsets"
and the concern about abrading pipe due to constant movement as a result of temperature changes. Straight runs are always attainable with Composite pipe.
6. Effect of sub-zero Temperature
- 100 meter of Composite pipe with a 36oF (20o Centigrade) rise in temperature will expand 4.7 cms.
- 100 meter of CPVC pipe expands 12.3 cms. in the same situation.
- 100 meter of HDPE pipe expands 43.1 cms. in the same situation.
Freezing of water at sub-zero temperature leads to failure of rigid pipes. Hence, most of the metal pipes are not recommended to be used at sub-zero temperature. Copper pipes also cannot withstand multiple freezing cycles.
PVC and CPVC pipes are also rigid and not recommended to be used for sub-zero temperature.
PE pipes, being flexible, do not have any effect of multiple freezing cycles.
Composite pipes, when tested for multiple freezing cycles at following parameters, have passed the test for stipulated 5 cycles.
Internal pressure :
Ranging from -5 to –40 deg. c.
for sub-zero temperature 18 hours.
7. Ease in installation:
This property is generally governed by type of joints and time required for jointing, flexibility of the pipe and allowable bending radius, ease in handling (light weight) and availability of pipe lengths.
7.1 Type of joints:
GI pipes are always used with threaded joints. These joints may lead to failure over the time period because of corrosion. Failure of joint due to faulty jointing can also not be ruled out.
Copper pipes are safer, in case of solder as well as ferule joints. However solder joint cannot be done at the place of installation, particularly in case of concealed piping. Hence, the piping has to be completed outside and then fitted in the wall. In such cases, addition of a fitting or maintenance of piping becomes very difficult.
PVC pipes can be joined by solvent cement, which is quite easy. However the time required for jointing is quite high if the jointing quality is required to be good. Threaded PVC pipes carry the same disadvantages as GI pipes.
CPVC pipes are joined by solvent cement Jointing.
Shelf life of solvent cement is an area where precautions are necessary to avoid the use of ‘expired’ solvent cement as it is having shelf life less than 6 months.
PE pipes, with butt fusion joint carry the same disadvantages as soldered copper pipes.
Composite pipes are generally joined by compression fittings. Ease in achieving closer manufacturing tolerances facilitates the use of compression fittings. These joints are very easy, fast as well as safe against leakages.
7.2 Flexibility of pipe and allowable bending radius:
GI, CPVC and PVC pipes are rigid and hence cannot be bent. Use of elbows is essential. This leads to increase in number of joints and preparation of the ends for elbows in case of threaded joints, which ultimately leads to higher installation time.
Copper pipes can be bent with mechanical benders.
PE pipes can be bent to a radius of 25 times the diameter of the pipe. However, due to spring back property bent pipe is required to be rigidly clamped to keep the pipe in position.
Composite pipes can be safely bent by hand when used with protective support springs to a radius of 5 times the diameter of pipe. This facilitates the elimination of elbow joints at most of the places. Composite pipe has a unique property of “Stays in shape”. Once the pipe is bent it will remain in the same form without any spring back.
7.3 Ease in handling and availability of pipe lengths:
GI as well as copper pipes are comparatively heavier and hence handling is more difficult as compared to light weight PVC, CPVC, PE and composite pipes.
GI, CPVC and PVC pipes are available in standard straight lengths. This leads to wastages as well as/or increase in number of joints.
PE and Composite pipes are available in straight as well as coil lengths up to 100 meters and above. This facilitates easier handling as well as lesser number of joints with no wastage, with properly planned piping installation.
8. Flow properties for friction loss
Pipe internal surface finish directly governs the flow properties of the pipe. GI pipe, because of rough surface have very poor flow properties.
Flow properties of copper, PVC, CPVC, PE and Composite pipes are more or less same.
Air ingress can cause rapid corrosion of metallic components of plumbing system. In case of metal pipes, ingress can be via improperly made joints.
Plastic pipes are permeable to oxygen from air, thus providing a path for oxygen into the system water causing increase in corrosion. Tests on commercially available plastic pipes have shown that the permeability to oxygen is sufficiently high to promote unacceptable corrosion of components in internal plumbing system.
Composite pipe with aluminium barrier layer would appear to be best option as an alternative to other plastic pipes to reduce the corrosion of system components caused because of permeability of pipe.