P.E.S Laboratory Services for Polyethylene Pipes and Fittings

P.E.S Lab is one of the most well equipped labs in the PE pipes & fittings industry in Iran. P.E.S Lab has been active for over two decades as an accredited lab of Institute of Standards and Industrial Research of Iran for testing PE pipes, fitting and raw materials. P.E.S Lab holds ISO/IEC quality management certificate from National Accreditation Center of Iran.

Equipped with skilled polymer experts and modern European equipment, P.E.S Lab provides a wide range of services to domestic and foreign customers. Such services include issuance of product quality certificates, test reports, data analysis, consultation and checking inconsistencies.

Our priorities in providing services to customers:

  • Precision and accuracy
  • Timely turnaround for tests and results.
  • Reporting impartial and reliable results
  • Taking advantage of novel technologies, standards and knowledge of PE industry for test methods and analysis of results


  • Tests
  • Laboratory Equipments
  • Test Report
  • Laboratory Testing Inquire


1. Melt flow rate (MFR)-ISO1133

This test measures the melt flow rate of raw materials at a constant time and temperature for evaluating the behavior of materials in the extruder to provide a proper process. This test is performed on raw materials to verify their quality and determine their viscosity. The results of this test on the product are used for quality control of production process and comparing them with those obtained for raw materials. According to the standards, the difference between the melt flow rate of product and raw materials should not be over 20%, otherwise the production process will require new settings.

2. Density measurement (ISO 1183)

The density of PE raw materials and products is determined by floating them in a fluid with a certain density (methanol).

  • The density of product represents the quality of production process and optimal conditions.
  • The favorable density of PE products is less than 0.950 g cm-3.

3. Carbon black percentage (ISO 6964)

To increase the resistance of PE pipes to ultraviolet (UV) radiation, carbon black should be added to the raw materials during the melting process. Due to very good UV absorption properties, carbon black is one of the best options for producing PE pipes. If carbon black content in the final product is less than required level, the polymer lacks sufficient resistance to UV radiation. When carbon black level exceeds the permissible range of 2-2.5%, the pipe will be damaged due to stress concentration.

4. Carbon black distribution (ISO 18553)

An appropriate amount of carbon black in the final product is required to protect PE pipes to UV radiation, but does not guarantee UV protection. Due to their specific structure, carbon black particles form aggregates and stick to each other. So masterbatch mixing process should properly distribute carbon black particles on PE surface in addition to dispersion and crushing. This will lead to efficient function of carbon black in PE protection.

According to recent studies, cracks start to propagate in pressurized pipes from carbon black aggregation sites, especially in the case of linear carbon accumulation, because carbon aggregates act like a foreign object in the pipe wall and cause fracture.

5. Tensile-compression and bending tests (ISO 9969-ISO 6259-ASTM 638)

Tensile test is one of the best tests for evaluating the quality of PE pipes. Various mechanical properties can be measured by this test. For this purpose, a specimen is prepared along the length of the pipes and then exposed to uniaxial tension at a certain rate. In this step, the specimen must experience a minimum plastic deformation of 350% of the initial length. Continuing the tensile test, the specimen is fractured and ultimately ruptured. Elongation percentage, yield point, break point and Young’s modulus are important mechanical specifications of the polymer reported in this test.

Maximum strength of the pipe against external load, bending strength and tensile and flexural strength of PE weldments can also be measured by this test.

The following items are of great importance in the tensile test indicating the quality of product, machinery, raw materials and production process:

  • Yield point
  • Elongation (a minimum elongation of 350% of the initial length)
  • Break and rupture points

The quality of pipe and raw materials can be found from the fractured and ruptured section of the pipe specimen.


6. Hydrostatic pressure test (ISO 1167, EN 921)

Hydrostatic pressure test is performed by most precise modern equipment in P.E.S Lab to evaluate pipe strength against internal pressures. After immersing the pipe in a water pond for 100 h at 20 ̊C or 165 and 1000 h at 80 ̊C, the pipe is placed under a constant internal pressure. The pressure is determined based on the pipe size and type of raw materials.

Any defect in the specimens (bursting, swelling, local swelling, leakage and hairy cracks) leads to rejection of the product.

A clear graph is prepared from the pipe behavior against applied pressure during the test to analyze the results.

7. Burst pressure test (ASTM 1599)

The above test is carried out on pipes up to 200 mm. For this purpose, the pipe is floated in the pond with a temperature of 23±2 ̊C and an incremental linear internal pressure is applied to the pipe until the pipe bursts in 60-70 sec.

A pipe made of high-quality raw materials by a correct process initially experiences a plastic deformation, swells and then bursts. In this case, the fracture cross section is perpendicular to the longitudinal axis of the pipe. Pipes that burst without deformation and swelling or those with a longitudinal fracture are not applicable.

8. Thermal reversion test (ISO 2505)

During extrusion for production of PE pipes, molten polymer chains are extended along flow direction and rearranged during forming and cooling. Therefore, extrusion intrinsically leads to residual tensions in the pipe. However, rapid cooling and inconsistent production and cooling rates and excessive residual tension may cause adverse effects on long-term performance of the product. Therefore, the permissible limit of residual tensions in the pipe should be evaluated.

Longitudinal reversion test can be used to determine internal tensions in the pipes.

For this purpose, a pipe of a certain length is placed in a hot-air enclosure (110 ̊C) for a certain period for releasing residual tensions and rearrangement of polymer chains. The length marked before and after heating and reaching to the ambient temperature is measured and calculated as length variation to the initial length (the maximum permissible length variation is 3%).

9. Thermal stability test- EN728 (oxidation induction time, OIT)

The resistance of a substance to oxidation is called oxidation induction time (OIT) and determined by thermal analysis. OIT is defined as the interval between the onset of thermal oxidation of a substance at a certain temperature under oxygen atmosphere and onset of degradation reaction.

During production process, raw materials resident a certain time in the extruder and mold. Therefore, polymeric materials should have good thermal stability to be not degraded. A certain amount of an antioxidant is added to polymeric materials in petrochemical complexes to provide a good thermal stability and prevent degradation.

This test is used to examine the quality of raw materials and final product. The oxidation induction time of final product is less than that of raw materials due to consumption of antioxidant during the process.

If OIT of final product is significantly reduced, the raw materials may be degraded due to inefficient processing.

10. Pipe appearance (ISO 11922)

Despite simplicity, checking the appearance of PE pipes is considered an important quality control test. PE pipes should be free of any internal and external imperfections and deep porosities. Partial dents can be omitted if the thickness is not reduced below the permissible limit.

11. Dimensional measurement and control (ISO 11922)

The exact thickness of pipe wall is determined by calibrated calipers at cross section and ultrasonic thickness gage along the length of a pipe.

The outer diameter of the pipe is measured by a scaled metal strip (micrometer) along the length of a pipe and an average diameter is reported.

12. Ovality test

According to standards, deformation of pipe cross section and ovality are measured after pipe production. The permissible limits for diameter and thickness variations have been specified in INSO 14427.

It is noteworthy that flexible PE pipes are deformed during storage, transportation and installation. After placing the pipe in the welding machine and joining, the pipe completely returns to its initial shape after installation, fluid flow in the pipe and applying pressure.

The list of equipment under P.E.S Lab scope





Hydrostatic machine IPT, Germany (21 stations)

Hydrostatic test, burst test


MFR machine, Germany

Determination of melt flow rate


Oven, National, Germany

Determination of carbon dispersion


Universal tensile machine, Testometric, England

Tensile, flexural, compressive tests


Dumbbell press machine, Gotech, Taiwan

Preparation of dumbbell tensile specimens


Apparent density, IPT, Germany

Apparent density


Carbon black machine, Germany

Determination of carbon content


Precise digital scale, AND, Japan

Density determination


15 and 20 cm digital calipers, Mitotoyo, Japan

Size measurement


Micrometer (20-2400 mm), Germany

Diameter measurement


OIT, Germany

Oxidation and thermal stability


Microscope with analysis software

Carbon dispersion


Moisture content, AND, Japan

Moisture content


Squeeze off, Iran

For gas pipes


Circulating oven, Binder, Germany

Thermal reversion test


CNC, IPT, Germany

Preparation of dumbbell tensile specimens

* The results of PE pipe tests are analyzed with the help of MiniTab.

Test Report

Production Date:

Date of Sampling:
Customer name:
Prototype Model:
Batch Nr:



Test Method

Test Name





Outside Diameter(mm)





Wall Thickness(mm)

E=(A-B)/(A)*100<12 %



INSO 7090-1(A)



(23 OC ±2 OC)

L1= mm

L2= mm

ΔL = mm

ΔL≤ 3%(L1)= %




Heat Reversion(mm)

(110 OC - h)



INSO 6980(A)


(190 OC /5kg)




ISO 6964

Carbon Black content(%)

(550±50OC -45min)


Grade ≤ 3



Carbon Black Dispersion


> 20 Minute

ISIRI 7186-6

OIT (210°C)

Gas Type:Nit(50ml/min)

Rate:20 OC /min

P= bar

T= Sec

Type of failure=ductile

P= bar

T= 60-70Sec

ASTM D 1599

Burst pressure(bar)

(Not applicable for OD above 200 mm)


P= bar

t= 165 h

T= 80 OC

Hoop stress= 5.4 N/mm2

ISIRI 12181-1

Hydrostatic Test

(Water in Water)

Type of Cap(A)

Strain Break = %

Stress @ yield = N/mm2



Tensile Test (N/mm2)


INSO14427-2/Company/ DOmm/SDR/P/W/PE/

L/PN/ Date

INSO 14427-2


Non Acceptable [ ]
Acceptable [ ]
Test Result are:
Lab Supervisor & Signature: A.Haghighi
Lab Report. #:
QualityControl Management & Signature: M.Davarpanah

Customer Representative Approval:
(if Requested)



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