2015-05-13 04:55:59

FAQS For Multilayer Pipes

Q: What is multilayer Pipe?

A: Multilayer Pipe is made of five layers. The inside & outside layers comprise of HDPE/PEX/PERT tightly bonded with melt adhesives to intermediate layer of Aluminum Core, which is longitudinally overlapped welded or laser welded. These Pipes offer the advantages of both metal and plastic pipes with none of their shortcomings.


Q: What is the use of Aluminum in the Pipe?

A: After extrusion of internal and external layers of HDPE material together with melt adhesive, the tube function as single component for operating in temperature range of -40C to 95C and there is no differential expansion of HDPE layers and aluminum tube. Because of aluminum in between, the resultant thermal expansion coefficient is low. It also sustains more pressure because of aluminum core inside.


Q: What are the advantages of Risong PEX-AL-PEX multilayer Pipes over GI Pipes?

A: The working Life of PEX-AL-PEX multilayer pipes is about 50 years and GI Pipes have very small life (depending of type of water) because of corrosion problem.

Because the internal surface of the multilayer pipes are smooth, the flow rate of fluid is in these pipes is 30% more than GI Pipes

PEX-AL-PEX multilayer Pipes are bendable and hence require less number of fittings

PEX-AL-PEX multilayer Pipes & Fittings are hygienic, toxic free and has no growth of micro organism.

PEX-AL-PEX multilayer Pipes are light in weight and come in coils of 500/50M lengths, therefore easy to carry, store and less joint.

They are corrosion resistance and Scale Free.


Q: Can Risong multilayer pipes be used for Hot Water?

A: Risong PEX-AL-PEX multilayer Pipes and PERT-AL-PERT multilayer pipes can be used for hot water up to 95C. UV stabilized pipes are also available for external installations exposed to Sun. These Pipes are black in color.


Q: What is the Size Range of Risong PEX-AL-PEX multilayer pipes ?

A: Risong PEX-AL-PEX multilayer Pipes come in size range from 12mm internal ID and 16mm Od to 26mm Id and 32mm OD.


Q: What type of fittings is used with Risong PEX-AL-PEX multilayer pipes ?

A: We supply complete range of Brass Fittings with our Pipes which are of two types Screw brass Fittings and Press brass Fittings.


Q: What are Screw brass Fittings?

A: These fittings do not require any special tool. The pipe joint is achieved by tightening the nut against the coned shaped olive, the profiles of the two pieces are designed to cause a progressive shrinkage of the cone olive and distribute the compression force across all the contact surface. These fittings can be unscrewed and reused in case of any change in the installation layout.


Q: What are the fittings needed during installation?

A: All kind of fittings are available as per requirement. It can be Equal Elbow, Unequal Elbow, Male Elbow, Female Elbow, Equal Union, Unequal Union, Male union, Female Union, Equal Tee, Unequal Tee, Female Tee; Male Tee etc These fittings are compatible with all kind of fixtures.


Q: What are the Tools required for Risong PEX-AL-PEX pipes?

A: For Screw brass Fittings, Cutter, Reamer, Bending Spring and Spanner is required.
   For Press brass Fittings, Cutter, Reamer, Bending Spring, Pressing tools and its Jaws will be required.
For bending of long pipes, bending springs is also available.


Q: Are Risong PEX-AL-PEX multilayer Pipes costlier than conventional GI Pipes?

A: The Prices of Risong PEX-AL-PEX multilayer Pipes are less than GI Pipes but with Brass Fittings the overall cost of the installation may be higher by about 10-15 percent. But the life of the multilayer Piping System is much more than that of GI Pipe system.


Q: How do you claim 50 years working life of your Pipes?

A: The PE materials have very high resistance to ageing, if utilized at the pressures upto 10 bar and working temperature up to 95 C. Artificial ageing tests performed in the laboratory indicate that the pipe has a working life of more than 50 years.


Q: Are your Pipe UV Resistance?

A: Yes our pipes are UV resistant.


Q: How much is the Heat Loss in Hot Water Pipes?

A: The Co-efficient of Thermal Conductivity of PEX-AL-PEX multilayer Pipes is .45 W/mk, about 1/100 that of steel pipe but it is higher than the insulating materials. Normally there is no need of using any insulating material for Hot water distribution.


Q: Whether your pipe chemically reactive?

A: Risong PEX-AL-PEX multilayer Pipe do not react with chemicals. Below 60 C, PE is able to stand all kinds of acid and alkali solutions. It is static resistant and thus can be used in chemical industry without extra protection. The Brass fittings may not be suitable for all types of Chemicals and alkalis and will require compatibility check before installation.


Q: Up to what degree the PEX-AL-PEX pipes can be bending?

A: The bending radius may vary from 2.5 to 5 times the pipe outer diameter and the cross section at the bend remains constant. Once the pipe has been bent it remains in the desired position like a metal pipe.


Q: Is there any special tool required for bending the PEX-AL-PEX multilayer Pipes?

A: There are internal and external springs available as tool for bending the pipes for smaller sizes up to 2632. Pipe Bending Machine is also available .


Q: Can Risong PEX-AL-PEX multilayer pipes be connected with GI Pipes?

A: We have fittings available through which Risong PEX-AL-PEX multilayer Pipes can be connected with other category of Plumbing Pipes and Fittings.


Q: In Risong PEX-AL-PEX multilayer pipe is there any Pressure Drop because of Internal Fittings?

A: There will be some friction Loss in Risong PEX-AL-PEX pipe due to internal fittings but the overall performance of the multilayer piping System will be comparable as there are less number of fittings required.


Q: What about the Risong PEX-AL-PEX multilayer pipes burning resistant?

A: Risong PEX-AL-PEX multilayer Pipes do not burn readily due to internal metal layer. With the test by the national fire proof construction material quality supervisory test center, the fire resistance of pipe is proved to reach grade B1 of GB 8624.


Q: What is maximum length of the Risong Pipe without any joint?

A: Risong PEX-AL-PEX multilayer Pipes are offered in Coils. The length in the coil very from 50M to 500M depending of the dia of the pipe. The maximum length of the installation can be up to the length provided in the coil.


Q: What is maximum sustainable temperature of pipes?

A: The working pressure of vista Composite Pipes is as under

Pipe type
Max. Working Temperature 

Max. Working Pressure

Pipes for cold water
-40 to 60 ℃
1.0 Mpa
Pipes for hot water
-40 to 95 ℃1.0 Mpa
Pipes for gas
-20 to 40 ℃0.4 Mpa


Q: What are the applications of Risong multilayer pipes?

A: Risong multilayer pipes are used for Cold Water Hot Water and Piped Gas Distribution. Risong multilayer Pipes and Fittings are also used for Compressed Air Lines for Industrial Applications, Floor Heating Systems and Submersible Pumps.


Q: Can Risong multilayer pipes be used for concealed installations?

A: Yes, these pipes & Fittings can be used for concealed installations.


Q: Can Risong PEX-AL-PEX multilayer pipes be used for external installation exposed to Sun?

A: We have UV Stabilized Pipes available in all sizes. These pipes are of black color and are used for external installation exposed to Sun.


Q: Can these PEX-AL-PEX multilayer pipes be used underground in Lawns and Gardens?

A: These pipes can be used for underground installation in Lawns and Gardens and the soil will not affect the pipes. But after the installation, care should be taken that pipes are not cut during SPADING WORK in the area of underground installation of pipes.

In some of the pipes white carbonation takes place after some ageing which results in blockage in pipes due to deposition of mineral substances in the Pipes.


Q: What is the solution to this problem in PEX-AL-PEX multilayer pipes?

A: Since, there is no bonding between PE and minerals, the minerals separated from the stagnant water can not stick to the wall of the pipe (scaling) and are flown out of the piping system when flow starts.


Q: Whether the stability & durability of PEX-AL-PEX multilayer pipe will be at par with GI system?

A: The stability and durability of PEX-AL-PEX mutilayer Pipes and Fittings are much better than GI system. GI system life is much shorter than multilayer Pipes System due to corrosion effect on GI Pipes.


Q: What is the Standard to which Risong PEX-AL-PEX multilayer pipes conforms?

A: Risong multilayer conforms to ASTM F1281/1282 specification. The Chinese Specification GB/T 18997 is also based on ASTM F 1281/1282.


Q: Is there any effect of Corrosive Soil on the Risong PEX-AE-PEX Multilayer Pipes?

A: No there is no effect of corrosive soil on the composite Pipes.


Q: Can these multilayer pipes and fittings be used for Compressed Air applications?

A: Yes, Risong multilayer Pipes and fittings can be used for compressed Air applications.


Q: Can these Multilayer pipes and fittings be used for RO Systems?

A: Yes, Risong PEX-AL-PEX Pipes and fittings can be used for RO systems.


Q: Can these multilayer pipes and fittings be used for Solar Water Heater?

A: Yes, Risong PEX-AL-PEX multilayer Pipes and fittings can be used for Solar Water Heater.


Q:How do you compare your Multilayer pipes with PPR Pipes?

A: Linear Thermal expansion is approx 7 times more in PPR as compare to Risong PEX-AL-PEX Pipes. As a result of this PPR Pipes develops cracks in the Plaster and also results in leakages on joints.


Q: How do you compare your PEX-AL-PEX pipes with C-PVC Pipes?

A: Hairline cracks develop in C-PVC Pipes while lying at site in open space which widens with the passage of time resulting in leakage.

Plumber has to wait for one joint to dry before he works for another joint on the same installation.

Pipe lengths are small and require more number of fittings. In our case Pipes are of 500M/400M/300M/200M/100M/50 M lengths.


Q: What type of clamps is used for holding the PEX-AL-PEX multilayer pipe in concealed installation?

A: There are no special clamps required to hold the pipe as the stresses are very low and the Risong multilayer Pipe is totally malleable and does not have any spring back action once formed into curves.


Q: What is Mpa?

A: Mpa (Mega Pascal) is unit of Pressure.
1 Mpa = 10 Bar = 1 N/mm2 (Newton per sq mm) = 145 psi (Pounds per sq inch)


Q: What is the operating temperature range of PEX-AL-PEX multilayer Pipes?

A: Because Risong PEX-AL-PEX multilayer Pipes are flexible and can withstand the stresses, developed due to increase in volume because of formation of ice at subzero temperature. PE and Aluminum both do not loose any strength at sub-zero temperature up to -40 C. Therefore the Pipes will not have any effect up to 95 C.


Q: Is there any effect of dissolved chlorine in the water on the multilayer Pipes?

A: Dissolved Chlorine does not have any effect on PE, hence there is no adverse effect.


Q: What is the solution if the Pipe gets punctured while drilling or hammering a Nail in the wall?
A: Normally the PEX-AL-PEX pipes are installed approx 18 to 20 inches from the floor and no nails are required to be hammered at that level. But in case the pipe is punctured it can be repaired very easily by fixing one Equal Union at the point of puncture.


Q: Will the strength remain same after bending?

A: The minimum bending radius of Risong multilayer Pipes can be up to 5 times the Outside Diameter. The tensile and compressive stresses developed on outermost and innermost layer of the pipe cross section, respectively, are well within the allowable limits when the bending radius is more than or equal to 5 times of OD of pipe. Hence the pipes bent within this limit are safely used without any reduction in basic strength of pipe.


Q: Which is the difference between PEX/Al/PEX and PERT/Al/PERT multilayer pipes?

A: PEX/Al/PEX multilayer pipe is composed by crosslinked PE, so the heat and mechanical stress resistance are improved during the crosslinking procedure. PERT/Al/PERT multilayer pipe is composed by PE with a chemical additive, so that it can be used with hot water, but it is not crosslinked. PERT/Al/PERT multilayer pipe is generally used in under floor heating and under floor cooling systems.