Corrugated Pipes

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Obsolete and inadequate sewer pipes, intense rainfalls, and frequent landslides require innovative solutions for the disposal of large quantities of storm water. Sewage pipelines nowadays, have to bear all internal and external stresses that are potentially damaging the sewage systems. Japan was the first country, that came up with a new technology in the 1990s, to manufacture sewage pipes in large sizes with high mechanical strength and low weight to solve their problem .As a result, the transportation and installation process have became a lot more convenient. The Rothen Plast production group in Iran, is now manufacturing polyethylene sewage pipes with great advantages such as resistant against abrasion, corrosion, and chemical fluids, light weighted, quick and easy installation with the properties of steel. The spiral corrugated polyethylene pipes of Rothen Plast, are made of polyethylene materials and a layer of steel profile. In other words, these pipes contain an inner layer in polyethylene, an outer structured wall in polyethylene and a core of galvanized steel covered by a polyethylene-based primer, which ensures a perfect blending with the two walls. The combination of these two materials, along with the use of an omega-shaped profile, ensures a performance that is by far better than other type of pipes such as fiber glass, concrete, and cast iron available on the market.

The presence of the steel has several advantages: higher resistance against pressure (up to 20 kN/m2), smaller thickness of outer layer, which reduces the amount of raw materials in production, and better long term performance. Rothen Plast manufactures the spiral corrugated pipes in different diameters from 600mm to 2400mm, to represent the best solution to business and technical needs of designers, project managers, and construction companies.


Rothen Plast manufactures the HDPE spiral pipe with galvanized steel reinforcement suitable for sewage systems, drainage systems, and ventilation ducts, in accordance with ISIRI 18781 and ASTM-F 2435 standards. The inner surface of these pipes is smooth, and the outer layer is in corrugated shape, reinforced with galvanized steel. The welding process for these pipes is with Electrofusion method.

Ring stiffness classes according to EN ISO  9969:  2008:

Class A (= 8 kN/m2) corresponding to SN8

Class B (= 12 kN/m2) corresponding to SN12

Class C (= 16 kN/m2) corresponding to SN16

corrugated pipe


In 2015, Iranian National Standards Organization issued ISIRI 18781 standard which applies to PE spiral pipes reinforced with a steel profile completely embedded between pipe walls. These pipes have a smooth inner surface with a diameter (DN/ID) from 600mm to 2400mm and are used for sewage systems, drainage systems and ventilation ducts. Taking into account the features of an innovative product, the Rothen Plast group used the following references: American standard ASTM ( American Standard Testing  Materials) F 2435-07; Iranian  National Standard ISIRI 18781; German DIN 16961; European EN 13476 standard. European standards which arfe known as EN standards, were used as testing methods.


The pipes of Rothen Plast are marked with ISIRI 18781 standard.

Marking includes the following information:

Number of standard reference

Manufacturer brand and/or brand

Nominal dimension (inside)

Pipe class Example: A (= SN8)


Date of production

Marking is an essential element to enhance product traceability required by ISO 9001:2000 standard.

Non-marked pipes are not compliant with any standard.


The PE pipes reinforced with steel, are being used widely for various projects in the USA, Canada, Japan, Europe, Russia, China, and France for over a decade. The pipes of  Rothen Plast are manufactured  in  accordance with the technical requirements of ISIRI 18781 and ASTM F2435-15 standards .

Dimensional Table

Pipe form 6 to 12 M long are available upon customer’s request.

Dimensional table

Weight of the pipe

The particular and innovative structure of polyethylene pipe produced by Rothen Plast, is reinforced with an omega shape profile made of galvanized steel which is entirely embedded between two polyethylene layers. By this design, the pipe will be lighter in weight and more stronger than similar types of pipes with high ring stiffness. The average weight of a spiral pipe DN/DI 1200 SN8 is 70 kg/m. on the other hand, the weight of an traditional polyethylene spiral pipe is about 120 kg/m and a concrete pipe is more than 1900 kg/m.The light weight of Rothen Plast pipes does not affect the ring stiffness and ensures the following advantages:

  • Affordable prices
  • Quick and easy installation
  • Lower transportation cost due to ability of storing smaller pipes with lower diameter within larger pipes
  • No expensive equipment is needed for installation process

Ring stiffness

The ring stiffness of these pipes is in accordance with EN 476 ( 1997 ) standards. This indicates the resistance of the pipe against vertical  deformation due to external pressure .

S : ring stiffness [KN/m2]

E : modulus of elasticity with transversal bending [ kN/m2 ]

I : longitudinal inertial moment of the pipe wall, cross section for every unit [m4/m]; the value is equivalent to the ratio I = s3/12

where s is equivalent to pipe thickness

D : neutral pipe wall diameter [m].

The vertical deformation of the pipe depends on the type and volume of the soil surrounding the pipe too. The ring stiffness may be determined using the method reported in EN ISO 9969 (2007) standard.

Junction System

One of the most relevant factors to determine the quality of a pipeline is the ability to  convey fluids and preventing potential damaging leaks in the junction system. Therefore, the junction between pipes is a crucial issue, especially in those projects that require involving pipes with high internal diameter (e.g. DN > 1000mm) and where groundwater   flows, affects the working environment . Although, they are mainly non-pressure sewage  systems and drains, it is necessary that the  junction system proposed by the manufacturer, ensures efficiency and long-term performance. The junction between the pipes is made by Extruder and Electrofusion welding, and the fittings are in corrugated  shape with a smooth inner surface. This manufacturing method ensures a higher ring stiffness and increases the resistance of the product in the most critical sections of the pipeline which is the junction. Before installation of the fittings, the pipe must reach ambient temperature.

The junction system of Rothen Plast ensures an easy and cheap laying with better safety.  The “male” and “female” components are manufactured in a special method that makes the laying and adjusting process much easier by using ordinary equipment and tools. The installation cost of these pipes is quite low due to convenient assembling. It is possible, upon request, to connect  Rothen Plast pipes by heat shrink method on the outer layer of the pipes, and then the inner layer of the pipes can be welded by extrude welding. The junction system of Rothen Plast ensures the sealing of the system. These pipes are  available in 6m, 9m, and 12m in length.

Physical/mechanical characteristics of materials

Rothen Plasts pipes are a combination of typical properties of polyethylene such as resistance against abrasion, light weight, minimum frictional resistance, resistance against chemical fluids, quick and easy installation; with the properties of steel, featuring  an elastic modulus 200 times higher than the polyethylene. The resistance of reinforced spiral corrugated pipes, and the polyethylene pipes against the chemical materials, is in accordance with ISO TR 10358.

mechanical characteristics
physical characteristics


The inner layer of Rothen Plasts pipe is made of polyethylene which ensures a high resistance against abrasion. Therefore, this pipe is a great choice to be used in the pipelines with high speed flow and slope environment (max speed up to 10 m/s) without producing relevant abrasion effects on the inner surface. The diagram shows how polyethylene pipes are more resistant against abrasion than other pipes made of other materials (concrete, fiber glass,clay, PVC, etc.)

Resistance to  UV rays

The outside black wall of this pipe is resistant against damages caused by environmental  factors and UV radiation, due to the carbon black added to the polymer. Therefore, the Rothen Plast pipes can be kept in the outdoors.


Upon request, Rothen Plast is able to supply a complete range of products for every required diameter and ring stiffness, such as: elbows, tees, manholes, and etc. The pipes manufactured at Rothen Plast can get connected with other similar pipes (HDPE corrugated pipes, HDPE pipes, PVC pipes, etc.) by their special fittings.

accessories corrugate

Transportation and relocation

The reinforced spiral corrugated pipes must be handled according to the requirements generally observed with traditional pipes. Rothen Plast pipes can be stacked up without any problem thanks to their light weight and high ring stiffness. Loading, transporting, unloading, and all related operations must be carried out with great care, by using means and devices appropriate to the type of pipes, and taking all the safety measures in order to avoid breakage, cracks, and damages. The pipes should be stored in a flat and safe  area. The first row of the pipes that is placed on the ground must be arranged to avoid possible damages to the outer surface, such as bending and deformation.

Stacked pipes must be protected with appropriate wedges in order to prevent sudden falls.

The spiral double-wall corrugated pipes, have a high ring stiffness due to their design. The HDPE-PP raw materials are more resistant against chemicals compared to all the plastic materials. Therefore, Rothen Plast offers corrugated pipe as the best choice in terms of resistant against chemicals. The studies show that corrosion in metal and concrete sewer pipes, are more than pipes made of polymer. Corrugated and spiral pipes are resistant against acids and bases. These pipes are not conductive and due to their weight, they are suitable for telescopic transmission (pipe in pipe) and also, they are optimized and convenient in terms of cost and installation time. Therefore, corrugated pipes, unlike concrete and metal pipes , do not need heavy equipment and high expenses to get installed. Corrugated pipes, compared to concrete and metal pipes are about 30 times lighter and they are recommended to be used in sewage systems as the best

option for longevity and  cost-effectiveness

A : Base fill

base of the ditch should be compact sand for AH should be minimum 150 mm for easy installation.

B : side fill

After the installation of the pipes by centering over the base fills are prepared out of compact ground cleared of keen and sharp particles

C : Upper fill

after completing the side fill the ditch is filled with the soil closed

CH should be minimum 500 mm extracted from the channel and closed CH should be minimum 500 mm.

SPR pipes


The SPR trench-less method is the best choice for pipeline renewal process and rehabilitation of large  diameter pipelines up to 5000mm. SPR utilizes steel reinforced interlocking PVC profile strips grouted in place with a high compressive strengths grout. The installation equipment can be used through standard access points with no need with no need for excavation. The Japanese SPR technology can also be installed in vertical applications such as water wells, access shafts, and other large diameter structures. The  SPR process is unique in providing a customized structural solution to eroding pipelines. This method can also be used to fix hydraulic anomalies as well as restoring the slope of the original pipe by appropriate engineering.

SPR pipes have been examined in accordance with Industry standards for spiral and PVC Profiled-wall pipes ASTM F 1697 and ASTM F 1741. Furthermore, the PVC profile of SPR contains Manning’s n of 0.01


The installation process of SPR pipe can be divided in the following steps:

  1. Inspection and cleaning of host pipe 2. Wound lining
  2. Installation of bracing system 4. Grouting


Prior to the SPR wound lining, the host pipe gets inspected via camera and all incrustation and debris should be removed by hydraulic jet cleaning.

 SPR wound lining

The SPR profile gets fed through the manhole into the winding machine placed in the existing pipe. Due to the forward motion, the winding machine moves to the next access  chamber. For longer rehabilitation sections, the profile gets cut off at the intermediate  shaft and the winding machine should be installed behind it to continue the winding process.

Bracing system

After the winding process is completed, the bracing system will be installed. The bracing material gets lowered through standard manhole openings. In the next step, the bracing system gets set up to provide structural support during the grouting process and positions the SPR profile in the existing pipe according to engineering specifications.


The grouting process is injection of grouting material into annular space between existing pipe and wounded PVC profile. The pipe will be ready to use after this stage.

Benefits of SPR at a glance

  • Rehabilitation of large diameter pipes (800-5000 mm)
  • Rehabilitation of circular, non-circular and custom shapes
  • Truly trench-less – requires only standard manhole entry
  • Designed for installation in live flow conditions
  • can be installed in curves and bends
  • Improved flow with smooth PVC material (Manning’s n of 0.01)
  • Environmental – friendly installation and application
  • Over 400 km successfully installed world-wide



The SPR PE pipe is a great choice to restore and rehabilitate the hydraulic efficiency, reliability, and integrity of old sewage systems, drainage systems, and culverts. The fully encapsulated steel reinforcement, is designed to provide a liner of optimum stiffness. The SPR PE pipes can structurally rehabilitate brick, concrete, glass reinforced plastic, corrugated metal sanitary sewer and storm-water pipelines with diameters from 900mm to 3000mm. The plastic profile that forms the pipe is provided in a range of sizes. The profile is reinforced with steel that is completely encapsulated within the HDPE material. The steel reinforcement is selected to provide a pipe with sufficient stiffness to meet the requirements of the project.

Project experiences

SPR PE has been used to rehabilitate sewage system, storm-water lines, and culverts  around the world . It has been proven capable of providing a structural pipeline for severely deteriorated pipelines. Also, it is capable of getting installed under difficult site conditions with minimal community disruption.

 Easy  mechanical   installation

At first, the deteriorated pipeline gets cleared of debris and obstructions, cleaned and inspected. Then, the diameter gets measured and approved. After this stage, the winding machine gets lowered to the base of the access chamber through the standard manhole  openings, and the reinforced HDPE profile gets fed into the machine form an above ground spool. The winding machine then starts the wound lining process and forms the reinforced HDPE into a new pipe. The process continue until the liner wounded by the winding machine reaches the end of the pipeline. The end of the liner at both access chambers gets sealed and rendered.

The annulus between the fixed diameter liner and the host pipe can be filled with grout  immediately after the winding is completed.

Proven pipe material

  • Made from similar grade of HDPE as new sewage and drainage pipes
  • Cell Classification of 33540C(or E)in accordance with ASTM D 3350
  • Profile sealing is achieved by extrusion welding to produce a continuous joint-less HDPE liner
  • Consistent material properties. The strength of the pipe does not rely upon the grout.


Numerous industry specifications provide design methods applicable to SPR PE, including :

  • ASTM F 1741: “ Standard method for installation of winding machine is available. This standard has been modified for SPR PE (HDPE) pipe.

The best solution in whole world

The modern urban life would be utterly impossible without underground infrastructure. Furthermore, it is becoming apparent that underground infrastructure system in the whole world, is substantially deteriorating as a result of age and increase in traffic loads. Additionally, the demand for sustainable and environmentally-friendly urban development is rising and this can pose a great challenge to local authorities. SEKISUI SPR, offers the best solution to these demands. The Trenchless technology has made the renovating the underground infrastructure a lot more simple and affordable, by rehabilitating and improving the existing system. This method, eliminates the protracted construction and modification of the cityscape. It also makes the expand and maintenance of the existing infrastructure system possible without excavation. The Trenchless technology, guarantees a much quicker, cost-effective, and environmentally-friendly solution, instead of replacing the system. SEKISUI SPR, employs the world’s best technical and operational infrastructure specialists, therefore, they can offer the best solution for all requirements from planning to construction. SEKISUI SPR operates in three divisions in order to answer to the needs of the customers; Sales and support, Trenchless Infrastructure Solutions, and construction. This provides a global interchange of experience for all experts to devise the optimum infrastructure solution for the projects. SEKISUI SPR brings together the competence of the SEKISUI Chemical Corporation (Osake). This is already represented in over 40 countries around the world.

Double wall corrugated pipe

Double walled corrugated pipe 110 mm

The HDPE pipes with polyethylene materials, can be produced in different grades from PE80 to PE100. It’s essential to use Anti UV and Carbon soot in the process of the production.

The corrugated pipes, are used in the water industry, drainage systems, ventilation systems and also they are used in collecting waste-waters from cities and villages.

The technical information of 110mm High density polyethylene (HDPE) double wall corrugated pipe:

Known diameter   110mm
Internal diameter   110+/-
External diameter   129
Ring resistance long term   31.5kN
Ring resistance short term   8SN
Length of the pipe 6m with coupler and washer
Length of the pipe 12m without coupler and washer
Height of profile  –
Thickness of internal crust  –
Liquefy flow index Equal or less than 0.7
Carbon percentage %1.2_%2.5
Marking According to standards

Reinforced spiral corrugated pipe

Reinforced Spiral Double wall Corrugated Pipe 1000 mm

The Rothen Plast manufacturer is the first and the greatest producer of Reinforced Spiral Corrugated Pipes, with an internal diameter of 1000mm and outside diameter of 1125mm, with PE 80 and PE100 grade of materials. The thickness of the inner layer of these pipes is 9mm and their ring resistance is 400kPa. These pipes can be produced at 6m, 9m and 12m in length.

The type of the sheets used in 1000mm reinforced spiral corrugated pipes, are ST12 oily sheet and Z20 galvanized with thickness of 1mm.

The 1000mm reinforced spiral corrugated pipe is being used in drainage system, collecting industrial and urban sewage.


The reinforced spiral corrugated pipe is a 5 layered polyethylene pipe that has been strengthened with metal. These 5 layers are:

Two layers of polyethylene glue, Black polyethylene layer,  Oily or galvanized ST12 metal, and, The inner yellow layer in thickness of 1cm.

The reinforced spiral corrugated pipe has a high ring stiffness and it is really resistant against ground vibrations.

The reinforced spiral corrugated pipe are being used in transferring rainwater, drainage system, urban and industrial sewage system. These pipes can be produced in two sizes of 6m and 12m in length.

High Ring Stiffness

The highest ring resistance of sewage pipes with plastic wall, is 8 SN. On the other hand, the polyethylene double-wall reinforced spiral corrugated pipe which is reinforced with steel, can easily provide 8 SN, 12.5 SN, 16 SN and even more if needed. In other words, this reinforced pipe can easily resist against corrosion because of its composite texture (steel and plastic).

The Rothen Plast’s 1000mm reinforced spiral corrugated pipe, has the certificate of 18781 Iran’s national standard, and also its being manufactured according to ASTM-F2435.

The technical information of 1000mm reinforced spiral corrugated pipe:

Internal diameter: 1000mm  1020mm = -/+ 0.02

Outside diameter: 1125mm

Type of raw material:  Polyethylene PE80-PE100

Type of the sheet:  Z20 or ST12

Thickness of steel sheet:  1mm-1.2mm

Width of steel sheet:  124.5

Thickness of yellow layer:  5mm

Thickness of black layer:  3mm

Thickness of black and yellow layers: 8mm

The gap between two crests:  150mm

Ring stiffness:   400kPa

Spiral Double-wall Corrugated Pipe

spiral corrugated pipe 1000 mm

The 1000mm Spiral Double-wall Corrugated Pipe, is in accordance with ISIR 9116-3 with ring stiffness of 4SN, 8SN, and 16SN, with PE80 and PE100 material.

The spiral corrugated pipe with internal diameter of 1000mm and outside diameter of 1008mm and 60mm in height of the profile, can be manufactured in two sizes of 6m and 12m.

All the quality examination of the products is happening in the company’s lab with the latest technology in the world.

The 1000mm Spiral Double-wall Corrugated Pipe, with 5mm in thickness of the inner layer, has 1020N of transverse tensile strength.

The raw materials of the pipes of this company are from Shazand, Amirkabir, and Maroon petrochemical and they have the approval stamp of standards.

The spiral corrugated pipe D1000 SN31.5


Type of examination Standard of examination Acceptance criteria
Appearance ISIRI 9116-3     Flawless
Density ISIRI 7090-1/ISIRI 9116-3 0.941 – 0.965 g/cm3
Melt flow rate(MFR) ISO 1133 / ISIRI 9116-3 0.15≤  < 0.7 g / 10 min
Ring stiffness(long term) ISIRI 9116-1 / DIN 16961 KN / m2 31.5≤
Ring stiffness(short term) ISIRI 11436/ ISO 9969 8 KN / m2≤
Flexibility 30% ISIRI 12190/ISO13968 No power drop and pipe breakage
Percentage of soot ISO 6964/ ISIRI 9116-3      2-2.5%
Soot distribution INSO 20059 / ISIRI 9116-3 Distribution rate A1,A2,A3 or B3 ≥
Oxidation Induction Time(OIT) ISIRI 9116-3 /ISIRI 7186-6 ≥20 min

Heat resistance


ISIRI 9116-3 / ISIRI 17614

No corrosion, crack and bubble on the surface of the pipe


Internal diameter DIN 16961 / ISIRI 9116-3 995±2 mm
e5,min ISIRI 9116-3      mm 8±1
Height of profile ISIRI 9116      95±2mm


Profiled-wall Polyethylene Pipe

Profiled wall Polyethylene Pipe 1000 mm

Profiled-wall Polyethylene Pipe

To increase the ring stiffness, the corrugated pipes surrounded by polypropylene material, come in hand. The cost of manufacturing these corrugated pipes is low due to their hollow structure.

There is no difference between profiled-wall pipes and spiral pipes in the resistance, but the corrugated pipes are better in the production of water tanks due to their lower ring stiffness compared to other double-wall pipes.

The profiled-wall polyethylene pipes are manufactured in spiral and connected tapes shape.

The polyethylene corrugated pipes are produced in three different ring stiffness of 16kN, 31.5kN, and 64kN.

In order to bury the pipe in depths more than 1.5m, the corrugated pipe with ring stiffness more than 16kN should be used.

The Rothen Plast production group is the first manufacturer of the double-wall Profiled-wall Polyethylene Pipe in high diameter. This company is also the first company that received the 9116 national standards in Iran, which, by using the most modern technology in the world in accordance with DIN 16961 and ISO 13476, has the ability to manufacture profiled-wall pipes in various diameters from 300mm to 3500mm with 6m in length.

Rothen Plast is one of the largest manufacturers of polyethylene pipes and fittings in large dimension. This company with more than 25 years of experience, by utilizing the most advanced technology in the world and modern European machinery, is able to manufacture double-wall and multi-wall pipes.

The applications of the profiled-wall polyethylene pipes:

The usage of the profiled-wall polyethylene pipes is increasing due to their advantages such as being resistant against corrosion in various environments, their light weight, convenient in transportation, simple production process, possibility of production with high diameters, and etc. This pipe is a good candidate for replacing the other pipes. The double-wall profiled-wall polyethylene pipe, have found various applications due to the strength of the inner and outer layers as well as having high resistance in environments with different properties.

The profiled-wall polyethylene pipes are being used in various projects such as:

-Urban and industrial sewage networks

-Agricultural, urban, and industrial drainage systems

-Water supply and irrigation networks

-Transfer of industrial materials such as acids, bases, salts, and etc.

-Material and liquid storage tank.

The 1000mm profiled-wall polyethylene pipe has a special type of profile made of PP, in corrugated shape. This type of structure distinguishes this pipe from similar pipes in terms of durability.

The 1000mm profiled-wall polyethylene pipe, is being used in various projects such as water and sewage systems, drainage system, and transferring water from sea. Unlike similar pipes (corrugated, Spiral, etc.), this pipe has a different body structure and has variety in production.

Having 70 types of profiles in different sizes and geometric structures in these pipes that are designed by the engineering unit and the monitoring unit for any project with any burial depth and conditions.

The 1000mm profiled-wall polyethylene pipe has a special structure compared to similar pipes. These pipes can be connected with coupler and washer made of EPDM. And sometimes, the electrofusion method can be used for these pipes. The design of this pipe can be different for various depths.

The use of 1000 mm profiled-wall polyethylene pipe in vertically or horizontally position changes the structure of the pipe at the time of production. Therefore, this pipe manufactures in accordance with the order and plan of the customer.

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