Testing - Teppfa

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1 Structured Wall Piping Systems according to EN13476 vs2

Structured Wall Piping Systems according to EN13476

IntroductionThis document will introduce the key aspects and highlight the main performance characteristicsof the new standard for structured wall piping systems EN13476.Due to a favourable ratio between price and performance, plastic pipes and fittings have achieveda strong market position in storm and foul water systems over the past decades. Leak tightness,ease of installation, and durability are some of the major benefits of plastic systems.The growing market share of plastic pipe systems is partly the result of continuous innovation,resulting in more effective and efficient concepts. These innovative concepts, like structured wallpipes, can only be successful when serving the basic customer need: quality.In order to safeguard customer needs, the plastic piping industry is involved in the development of high quality standards that serve this purpose.Next to safeguarding good quality, standards should also provide transparency in the performanceof pipe systems to benefit network designers, owners and installers.Indeed, EN 13476 is a good example of a performance based standard that ensures that the

systems comply with the level of transparency set by the standard.

The European Plastic Pipes and Fittings Industry strongly support an effective implementation of this standard throughout Europe.The commercial and technical staff of manufacturers producing these types of pipes and fittings iswell prepared to answer any further question you may have.

ContentsThis document contains short explanations of the main performance characteristics of StructuredWall Pipes and Fittings made according to EN13476:

1. Ring Stiffness of Pipes and Fittings and Available Classes2. Required Ring Flexibility of Pipes

3. Dimensions and Tolerances4. Impact Strength, Resistance to Dynamic Loading5. Demonstration of Leak Tightness of the System6. Resistance to High Temperatures7. Recommendation for Sewer Pipe Cleaning, Jetting8. Demonstration of the Durability of the Used Thermoplastic Materials9. Chemical Resistance of the Used Thermoplastic Materials10. Additional Information: Recycling of Thermoplastic Pipes and Fittings

+ addendum




Ring Stiffness

System performance and customers benefitsThis method simulates the behavior of the system during and after installation. When buried, a pipe

must show sufficient stiffness to withstand the load from the soil. Moreover, the pipe must be able toresist the extra pressure caused by road traffic. The ring stiffness test determines the required level of stiffness for any given design, thus ensuring that the product will not collapse when buried and that nodefects will influence the performance of the product.

Test method The test is carried out according to EN ISO 9969 on a compression testing machine equipped with twoflat steel pates. For type testing the test samples must be 21 days old. Three pieces of pipe,conditioned at least for 24h at a temperature of 23

oC must be prepared for the test.

The test pieces are fixed between plates of the compression machine at 3 different positions. The ringstiffness is now determined by moving the plates toward each other and measuring the force neededto deflect the pipe, which will vary depending on the diameter of the pipe. Subsequently a graph of theforce versus deflection can be drawn up.

The ring stiffness is calculated as a function of the force necessary to produce a 3 % diametricdeflection of the pipe.Tests of the ring stiffness of fittings are carried out in a similar way in accordance with ISO 13967

Requirements According to the standard EN 13476 part 2 and 3;

The pipes and fittings shall be designated in one of the following nominal stiffness classes (SN):DN ≤ 500 : SN 4, SN 8 or SN 16DN > 500 : SN 2, SN 4, SN 8 or SN 16Pipe Ring Stiffness ≥ relevant SN [nominal ring stiffness].

In an installed structured wall pipeline the ring stiffness class must be the same for both pipes andfittings.

Test result for calculation

1% 2% 3% Deflection

TEST RESULT

F o r c e F

Compression testing machine




Ring Flexibility

System performance and customers benefitsThis method simulates the behavior of the buried piping system. The test is carried out to ensure thatthe installed piping system can withstand sufficiently external loadings during its expected lifetime.

The method warrants that the product will neither collapse, nor suffer defects even under highdeformation conditions or traffic loading.

Test methodThree 300mm long pieces of pipe which are conditioned at least for 24h at a temperature of 23

oC are

used for the test. The test is carried out according to EN 1446 on a compression testing machineequipped with two flat steel pates. The test pieces are fixed between the plates of the compressionmachine at 3 different positions. Each piece of pipe is deflected at a constant speed until a minimum of 30% diametrical deflection is achieved (alternatively 20%) unless a prior fracture has occurred. Thesample is monitored and visually inspected for signs of mechanical failure during the test. Theprocedure is similar to the ring stiffness test method. A graph showing the relation between force anddeflection should be drawn up after the test.

Requirements According to standard EN 13476 parts 2 and 3, there are two levels of requirements:

• Ring flexibility 30% diametric deflection – RF30 (recommended requirement)

• Ring flexibility 20% diametric deflection – RF20 (as exception possible for special conditionsand dimensions, to be defined in the national foreword)

During the test there must be no:- decrease of the measured force;- cracking in any part of the wall structure.

After the test there must be no:- wall delamination or other types of rupture in the test pieces;- permanent buckling in any part of the structure of the pipe wall including depressions and craters

in any direction.

Ring flexibility test.

30%20% 10%

Force F

Deflection

POSITIVE RESULT

Fmax

30%20% 10% Deflection

NEGATIVE RESULTForce F




Dimensions and tolerances

System performance and customers benefits

Basic geometrical characteristics are included in the standard EN 13476. Correct dimensions andtolerances assure that all system elements fit together and that joints can be assembled appropriately.This is also the crucial issue when it comes to ensuring the performances of the elastomeric sealingring joints. Pipes and fittings sizes are specified according to either their outside diameter DN/OD-series or their inside diameter DN/ID series. Standard EN 13476 specifies the following nominal sizes:

DN/ID [mm]: 100, 125, 150, 200, 225, 250, 300, 400, 500, 600, 800, 1000, 1200DN/OD [mm]: 110, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000,1200

Apart from diameter, the standard defines wall thicknesses for spigots, sockets and inner layers aswell as the lengths of products. Tolerances mentioned in the standard mainly describe one limit value:minimum or maximum.

Test method

All dimensions should be measured in accordance with EN ISO 3126 which precisely describesdevices and methods for the characteristics. The temperature of the device, test piece and ambient air must be set at 23

oC. Therefore, the test pieces should be conditioned at that temperature for a period

of time.

Measurement of the wall thicknessThe device is moved along the selected cross-section until finding the minimum value which isthe result.

Measurement of the mean inside/outside diameter The measured cross-section is divided into regular intervals. Depending on diameter, 6 to 8individual measurements are required. The average of the obtained values is the result.The measurement of the inside/outside diameter may also be carried out with directmeasurement using a "π" tape.

Requirements All results must be within the interval of tolerance specified in the standard EN 13476.

Outside diameter measurement. Wall thickness measurement




Impact strength

System performance and customers benefitsThis test is to ensure that the pipes and fittings will not be damaged during handling, transportation,

storage and installation. What could happen to the pipes and fittings before they are installed is

translated into an impact simulator which validates the thermoplastic pipes and fittings ability to resist

external and internal blows.

Test method for pipesPipes are tested according to EN 744. Lengths of pipe representative for a batch or a production runare taken from an extruder from which the test pieces are cut. These pieces are subjected to blowsfrom a falling weight (striker) dropped from a specified height (created by a mainframe) to specifiedpositions around the circumference of the pipe (bedded on a rigid 120° V-block support), with a testtemperature of 0°C. (round-the-clock method)Unless otherwise specified, consider the test piece as a failure if the impact causes shattering or anycrack or split on the inside surface of the pipe that can be seen without magnification.The point of failure is estimated as the true impact rate (TIR) of the batch, or production run, where themaximum value for TIR is 10%. [TIR = the total number of failures divided by the total number of

blows, in per cent, as if the whole batch had been tested].Variables are a) the type of striker, b) drop height, c) temperature, d) the method of sampling and e)the number of test pieces.

Test method for fittingsFittings are tested according to EN 12061. Test fittings are dropped at a test temperature of 0°C at a

specified height depending on the dimension.

Requirements According to the standard EN 13476 parts 2 and 3, there is only one level of requirement for Impactstrength: TIR ≤ 10 % at 0°C.

Exceptions from these requirements can be defined in the national foreword:

• In countries where a less stringent impact resistance is permitted, a test temperature of 23°C can be applied.

• In countries where a more stringent impact resistance is required, an impact test at -10°Caccording to EN 1411 (the staircase method) may be necessary.

Impact strength test equipment




Leak tightness

System performance and customers benefitsThis method ensures the system’s ability to hold fluids inside and outside the system(infiltration/exfiltration performances). The test also verifies the connection between the socket, the

spigot, and the elastomeric sealing ring. The tightness of the piping system refers to the environmentalprotection aspect. The method is applied to systems containing joints with an elastomeric sealing ring.The joints are tested under extreme conditions including joint angular and diametric deflection rangingfrom negative to positive. For underground drainage and sewage pipe systems this is a fundamentalcharacteristic.

Test methodThis test is carried out according to EN 1277. A test piece longer than two meters comprising pipe(and fitting) with at least one elastomeric sealing ring joint must be prepared. A special device is usedto assemble the joint and to close its free end. Additionally, clamps are also used as auxiliaryequipment for diametric deflection.The standard EN 13476 specifies two required test conditions: B and C.

Condition B – Diametric deflection of socket and spigot. This condition requires clamps to applydeflecting forces. The spigot has to be deflected up to 10% of the outside pipe diameter and thesocket up to 5% of its outside diameter.

Condition C – Angular deflection of the joint. If the socket is designed to take up an angular deflection,then this value should be added to the test value which is: 2

ofor outside diameter de≤ 315 mm, 1.5

ofor

315 mm < de ≤ 630 mm, and 1ofor de > 630 mm.

For both conditions, B and C, the test starts with a negative air pressure of p 1 = -0,3 bar. During thenext 15 minutes the loss of partial vacuum must not exceed 10% of the initial value. Then the testpiece is filled with water and hydrostatic pressure is raised to 0.05 bar for 15 minutes. At the end, thehydrostatic pressure is raised up to 0.5 bar for another 15 minutes. During this period of time, noleakage may appear at either pressure value.

Requirements According to standard EN 13476 part 2 and 3 for condition B and C, the elastomeric sealing ring jointshould be tight.

Leak tightness test.




Resistance to high temperatures

System performance and customers benefitsIn practical use, piping systems made of thermoplastics for drainage and sewerage must be resistantto the required temperature of the discharge. Therefore, the systems made of thermoplastics must beresistant to the following temperatures when installed in the ground outside of the building structure:

• Continuous water discharge of 45ºC for dimensions ≤ 200 mm

• Continuous water discharge of 35ºC for dimensions >200 mm

Because this type of piping system is allowed to be used in the ground below the cellar floor within thebuilding structure and 1 meter outside of the building structure, it must also be resistance to amaximum intermittent waste water temperature of 95ºC.

Test methodsEN13476 has references to the test methods described in EN 1437 and in EN1055, which are carriedout to demonstrate the fitness for use under practical conditions:

A test according to EN1437 is carried out to investigate the resistance of the sewer pipe system to

a combination of temperature variations and external loadings. An assembly of pipes and fittingsis installed in a box filled with sand to simulate practice.For pipes ≤ 160 mm, water with temperatures varying between 85ºC and 20ºC is run through thetest assembly with the total number of cycles of 2,500.For pipes > 160 mm a continuous flow of water with a temperature of 50ºC is run through the testassembly for 8 days.

After the test procedure, the test assembly is examined on leakage and mechanical stability of thepipe system.

A test according to EN 1055 is carried out to investigate the temperature resistance of the pipingsystem at elevated temperatures for pipes up to 200mm OD:

An assembly of pipes and fittings is fixed on a wall. A water flow with alternating temperatures of 93ºC and 20ºC is run through with in total 1,500 cycles.

After the test, the assembly may not show any no leakage and sagging between the fixing points

shall be limited.

Typical cycling test arrangement Elevated temperature test (1500 cycles)




Flushing of pipes (Jetting)

System performance and customers benefitsGravity drain and sewer systems require regular cleaning to ensure an efficient performance.Compared with other materials, plastic sewer pipes have a very low roughness coefficient. In practicethis characteristic provides an improved self cleansing and a reduced risk of blockages and blockageremoval at lower jetting pressures.

Two cleaning methods are generally used: either mechanical or hydraulic, both combined with vacuum.Hydraulic methods offer more benefits than the mechanical ones. This is especially due to their abilityto clean pipes, manholes and their covers, remove blockages in pipes and transport deposits tomanholes.

Annex D of EN 13476-1 has a short description of how an effective jetting of sewer piping systemsmade of thermoplastics should be carried out. This description is useful for owners of pipelines andcompanies that clean sewers. It clearly shows that the use of high volume water and low pressure isthe most effective way to clean plastic piping systems. This method furthermore has additionalbenefits of increased hammer action of the jet-head on blockages, cleaning the entire pipecircumference, and easy flushing of debris to manhole for convenient removal while minimizing therisk of pipe damage.

Applicable methodIn Annex D of EN 13476-1 a reference is made to CEN/TR 14920 “Jetting resistance of drain andsewer pipes – Moving jet test method”. This test is carried out with the following test parameters: Awater flow with 46 l/min through a ceramic jet nozzle at a pressure of 120 bar. The jet nozzle has anorifice diameter of 2.80 mm. The tested piece of pipe with a minimum length of 1.5m, or the jet nozzle,moves forwards and backwards in 50 cycles at a speed of 1 m/min.

Best practiceBased on independent laboratory test results, the following best practice principles for jetting arerecommended to achieve an efficient cleaning and unblocking of any sewer pipes:

• Use a low pressure/high volume jetting - those methods use a larger bore (typically

2,8 mm) nozzles• Avoid a high pressure/low volume cleaning technique which use a small bore

(typically 1 mm) nozzles

• Select a nozzle size appropriate to the jetting equipment and the size of the pipe

• the maximum pressure at the nozzle should be 120 bar, however, the requiredpressure for blocking removal in plastic pipes are as follows:

i. for grease – 70 barsii. for solids – 70 to 110 bars

View of the rig. Moving test of PVC pipe Testing a PE pipe. Nozzle view.

Source of all photos: TEPPFA, “Report TEPPFA task force jetting, technical”, Hammel, 2002




Durability

System performance and customers benefitsTo estimate the lifetime of a non-pressure piping system made of thermoplastics, a test method of

a relatively short duration is carried out to demonstrate the durability of the plastic material used toproduce the pipes and fittings.

Test methodIn EN 13476, internal pressure testing according to EN ISO 1167 is required to demonstrate thedurability of the plastic material used in the piping system.

The principle for this test is to use a combination of internal pressure and elevated temperature inorder to reduce the testing time to a practical level. EN ISO 9080 and other ISO standards areused to define the correct combination of the elevated temperature and the circumferential stress.The circumferential stress is used to calculate the relevant internal pressure for the dimension of the test.

Requirements

Each of the three types of plastic materials described in EN 13476 has the following testparameters (the difference between them is due to different material properties):

Circumferentialstress

Pipes & Fittings

Test temperatureRequired

Testing timeMaterial

[MPa] [ºC] [hours]

10 (Pipes) +60 1000PVC-U

6,3(Fittings) +60 1000

4,2 +80 140PP

2,5 +95 1000

4 +80 165

PE 2,8 +80 1000

Internal pressure test




Chemical Resistance

System performance and customers benefitsThermoplastic pipes and fittings are resistant to water and waste water from domestic andmunicipal sewerage. They are resistant to chemicals at normal temperatures and in smallquantities, which may occur in normal use. Due to different applications (especially in industrialuse), thermoplastic pipes may come into contact with various materials such as chemicalproducts, fuels, lubricants etc. both on the inside and the outside.

An attack from chemicals may cause a change in characteristics of the thermoplastic pipe due to acombination of the following factors: temperature, internal and/or external load/stress,concentration, frequency and the effect of mixture of chemicals.

As the conditions of use may vary from project to project, it is important for designers and end-users to consider chemically resistant thermoplastic pipes when designing a new pipeline. EN13476 offers support to deal with this matter.

RecommendationsTechnical Report ISO/TR 10358 shows the result of investigations, research and tests

regarding resistance to single chemicals for piping systems made of thermoplastics materials. EN

13476 recommends the use of this technical report as guidance when dealing with the chemicalresistance of piping systems made of thermoplastics. ISO/TR 10358 classifies the chemicalresistance of thermoplastic material such as PE-LD, PE-HD, PP, PVC-U, PVC-C, PB, ABS,PVDF and PE-X with respect to a wide range of temperatures and concentrations.

The classification of the chemical resistance in ISO/TR 10358, i.e. thermoplastic pipesmaterial, is divided into the following three classes: S (satisfactory), L (limited) and NS (notsatisfactory). It is highly recommended that designers and end-users check this technical reportwhen designing a piping system.




Additional informationRecycling

Recycling is a very good way to utilize resources. This applies in particular to thermoplastics pipesand fittings. The characteristics of this material allows for it to be reused for new pipes and other plastic products with a relatively low use of energy.

A system for collecting old plastics pipes was started up in the Netherlands about 15 years ago.Since, similar systems have been initiated in other European countries.The quality of the virgin raw material used to produce plastic pipes is set by international EN andISO product standards such as EN 13476. These standards not only ensure that high quality ismaintained. They also warrant a long life for the products.

EN 13476 also has rules on how to use recycled plastics materials. These rules make sure thatthe quality of the end-products is of a high standard.

In practice, a full circle for plastics pipes and fittings can be described by the following points:

• Collecting old pipes and fittings from the consumer

• Sorting, cleaning, and regrinding the pipes and fittings before packing the recycled rawmaterial

• Using the raw material to produce new pipes




Addendum

Norms referred to in this document:

EN 13476 Plastics piping systems for non-pressure underground drainageand sewerage

EN ISO 9969 Thermoplastics pipes. Determination of ring stiffness (ISO 9969:1994)ISO 13967 Thermoplastics fittings — Determination of ring stiffnessEN1446 Determination of ring flexibilityEN ISO 3126 Determination of dimensionsEN 744 Test method for resistance to external blows by the round-the-clock

methodEN 12061 Test method for Impact resistanceEN 1277 Test method for leak-tightness of elastomeric sealing ring type jointsEN 1437 Test method for resistance to combined temperature cycling and

external loadingEN 1055 Test method for resistance to elevated temperature cyclingCEN/TR 14920 Jetting resistance of drain and sewer pipes – Moving jet test methodEN ISO 1167 Determination of the resistance to internal pressureEN ISO 9080 Determination of long-term hydrostatic strength of thermoplastics

materials in pipe form by extrapolationISO/TR 10358 Chemical resistance of thermoplastic materials for piping systems

Used Abbreviations

SN Ring Stiffness classDN Nominal Diameter RF Ring FlexibilityDN/ID nominal size related to inside diameter DN/OD nominal size related to outside diameter PVC-U un-plasticized poly(vinyl chloride)

PVC-C Chlorinated PVCPP PolypropylenePE PolyethylenePE-LD PE of low densityPE-HD PE of high densityPB Polybutylene

ABS Acrylonitrile – Butadiene - StyrenePVDF Polyvinylidene FluoridePE-X Cross linked PEMPa MegaPascals

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