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Gravity Sewer Systems


Dupplex - robust double-wall piping system for sewer drainage

Uponor Dupplex Sewer System


Gravity Sewer Systems

5.3 Uponor Dupplex Sewer System The Uponor Dupplex Sewer System is designed for gravity sewerage applications. Dupplex is a polypropylene (PP) double-wall sewer pipe with a smooth inner wall and a corrugated outer wall. The system’s ring stiffness is SN 8. The Uponor Dupplex and Uponor Ultra Rib 2 sewer systems both use the same fittings range. These fittings are also used with the Uponor PP Stormwater System. The entire system meets SN 8 ring stiffness requirements and all components are made uniformly from PP. Coloured terra cotta on the outside, the pipe has a light grey inner surface, providing optimum visibility during camera inspection.

The Dupplex pipe outperforms all current European standard requirements for under­ground sewer systems. In addition, Dupplex’s strict quality requirements further enhance the system's reliability. Dupplex pipes are equipped with fixed sockets which, together with a sealing ring, ensure easy and secure coupling.


Pipe dimensions Outside diameter (mm)

Inside diameter (mm)

160 142 200 174 250 216 315 277 400 351

Table 5.3.1

After socket welding, all pipes are tested for tightness as part of continuous production quality control inspections. The Dupplex system is delivered with standard seals or oil/petrol resistant seals, as required. Its standard sealing rings are made from styrene butadiene rubber (SBR). Oil and petrol resistant seals are made from nitrile rubber (NBR) and marked yellow.

Uponor Dupplex Sewer System







ISO 1183

Ring stiffness




ISO 9969

Fittings SN8 kN/m2

Standard/test method

ISO 9969

Long-term elastic modulus E50



ISO 527-2

Short-term elastic modulus E0



ISO 527-2

Thermal expansion factor


mm/m • °C

Thermal conductivity


W/m • °C



Maximum continuous operating temperature Maximum momentary operating temperature



Max. angle of joint deflection



Gravity Sewer Systems

System and material specifications

DIN 52 612 / 23 °C

Table 5.3.2

Uponor Dupplex Sewer System


Gravity Sewer Systems

Approvals & Markings Approvals The Dupplex system carries the Nordic Poly Mark and is INSTA-CERT certified and approved in the Nordic countries (Finland, Sweden, Norway and Denmark).

INSTA-CERT certificates for all Uponor products can be viewed on our website at

Markings The markings for Uponor Dupplex piping are explained in the figure and table below.




Manufacturer Application Product

❄  ➃  2007

  EN 13476 

DN/ON 200




Nominal outside Stiffness

polypropylene diameter


Application area, UD = underground drainage and sewerage within the building structure and outside the building

EN 13476 Nordic Poly Mark



Snowflake symbol.

Production unit Production date:


Pipe can be handled

➃ = Forssa,


at low temperatures Finland

Table 5.3.3


Uponor Dupplex Sewer System

Structural design

Flow design

The “Structural design” section of the Drainage and Sewer Systems chapter specifies a number of design criteria for which generally applicable experiencebased data exists. If these criteria are met, no additional design calculations are required.

When determining the pipe system’s dimensions, to ensure trouble-free operation it is important to ensure that the system has sufficient flow and self-cleaning capacity. The main design principles are presented in the introduction section of the Drainage and Sewer Systems chapter. Based on a roughness coefficient value of 0.25 mm, flow charts for Dupplex pipe systems are presented in appendices 3.1, 3.2 and 3.3.

Gravity Sewer Systems

Dupplex Sewer System Design

Although pipe size is expressed using the outside diameter, the charts are based on the inside diameter. After the pipe design phase, the selfcleaning capacity and pipe gradient must be determined based on the chosen pipe size and design flow rate. For this purpose, self-cleaning diagrams of differentsized Dupplex gravity sewer pipes are presented in appendices 4.1 – 4.5.

Uponor Dupplex Sewer System


Gravity Sewer Systems

Dupplex Sewer System Installation This section gives step-by-step instructions on the jointing and coupling of Dupplex pipes and fittings.

Dupplex pipes use the same fittings as the PP Stormwater System and the Ultra Rib 2 sewer system.

Coupling Dupplex sewer pipes

1. Using a fine-tooth saw, cut the pipe between the ribs. Deburr the cut edges with a blade or file.

2. To ensure optimal tightness, fit a seal into the first groove from the pipe end.

3. Apply lubricant to the inside of the socket. To facilitate jointing, also apply lubricant to the spigot end sealing ring. Ensure that no sand or grit adheres to the lubricated areas.


Uponor Dupplex Sewer System

Gravity Sewer Systems

4. The joint is complete when the pipe end is pushed all the way to the base of the socket.

5. The pipes can also be slotted together by levering against the rearmost socket, e.g. with a crowbar. When doing so, to avoid damaging the socket position a piece of wood between the socket and crowbar.

6. Uponor Sewer System A correctly coupled Dupplex joint.

Uponor Dupplex Sewer System


Gravity Sewer Systems 86

Coupling a Dupplex spigot end with a concrete spigot end

Coupling a Dupplex spigot end with a concrete pipe socket

Fit the sealing ring onto the spigot end of the concrete pipe. Align the adaptor and push it fully home, so that the concrete pipe sits against the base of the adaptor. Carefully (do not use gas torch) apply heat to the coupling, to form a tight joint. No lubricant is used in the joint.

Fit the seal onto the adaptor so that the spigot end of the seal is towards the concrete pipe socket. Push the adapter into the pipe socket; the seal will roll into place. No lubricant is used in the joint.

Uponor Dupplex Sewer System