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:
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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.
The density of PE raw materials and products is determined by floating them in a fluid with a certain density (methanol).
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.
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.
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:
The quality of pipe and raw materials can be found from the fractured and ruptured section of the pipe specimen.
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.
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.
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%).
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.
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.
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.
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.
No.
Machine
Test
1
Hydrostatic machine IPT, Germany (21 stations)
Hydrostatic test, burst test
2
MFR machine, Germany
Determination of melt flow rate
3
Oven, National, Germany
Determination of carbon dispersion
4
Universal tensile machine, Testometric, England
Tensile, flexural, compressive tests
5
Dumbbell press machine, Gotech, Taiwan
Preparation of dumbbell tensile specimens
6
Apparent density, IPT, Germany
Apparent density
7
Carbon black machine, Germany
Determination of carbon content
8
Precise digital scale, AND, Japan
Density determination
9
15 and 20 cm digital calipers, Mitotoyo, Japan
Size measurement
10
Micrometer (20-2400 mm), Germany
Diameter measurement
11
OIT, Germany
Oxidation and thermal stability
12
Microscope with analysis software
Carbon dispersion
13
Moisture content, AND, Japan
Moisture content
14
Squeeze off, Iran
For gas pipes
15
Circulating oven, Binder, Germany
Thermal reversion test
16
CNC, IPT, Germany
* The results of PE pipe tests are analyzed with the help of MiniTab.
Result
Acceptance
Test Method
Test Name
DO=
INSO2412
INSO14427-2
Outside Diameter(mm)
TO=
Wall Thickness(mm)
E=(A-B)/(A)*100<12 %
d>0.941
INSO 7090-1(A)
Density(gr/cm3)
IL=Metanol
(23 OC ±2 OC)
L1= mm
L2= mm
ΔL = mm
ΔL≤ 3%(L1)= %
ΔL<%3L1
INSO17614
ISO2505
Heat Reversion(mm)
(110 OC - h)
0.15
INSO 6980(A)
MFR(gr/10minute)
(190 OC /5kg)
2-2.5%
ISIRI7175-2
ISO 6964
Carbon Black content(%)
(550±50OC -45min)
Grade ≤ 3
INSO20059
ISO18553
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
T= 60-70Sec
ASTM D 1599
Burst pressure(bar)
(Not applicable for OD above 200 mm)
SDR=
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
>350%
ISO6259
Tensile Test (N/mm2)
INSO14427-2/Company/ DOmm/SDR/P/W/PE/
L/PN/ Date
INSO 14427-2
Marking
Customer Representative Approval: (if Requested)
F-L-37-R-3