ISO 2505 Thermoplastic Pipes Longitudinal Reversion Test (PF Heat Reversion Test)

Information on the most widely used ASTM standards within the materials testing industry

Descriptions of the most prominent lSO standards within the materials testing industry

Standards including EN, DIN, JlS, and more

Mechanical testing of polymer materials in the automotive industry is directly related to the safety of components and the reliability of the entire vehicle. UnitedTest can cover mechanical performance testing for automotive interior and exterior parts, as well as functional components, adapting to automaker standards and providing comprehensive testing solutions including tensile, impact, and fatigue tests.

Mechanical testing in the battery industry determines the tensile and puncture resistance of core components such as separators and electrodes, directly affecting battery safety and cycle life. UnitedTest can cover full-dimensional mechanical testing of battery materials, compatible with national and international standards, and provide customized testing solutions.

Mechanical testing in the consumer goods industry determines product durability and safety, such as impact resistance for toys and fatigue resistance for home appliances, making it core to compliance and quality. UnitedTest can cover mechanical tests for all categories of consumer goods, including tensile, impact, and hardness tests, compatible with national and international standards, and offers customized testing solutions.

In the field of medical and biomedical sciences, mechanical testing determines the safety and compatibility of implanted devices and biomaterials, making it a core part of regulatory approval. UnitedTest can cover a full range of tests including tensile, fatigue, and wear tests, compatible with national and international standards, and provides customized biomechanical testing solutions.

Material strength is a course that most engineering fields are required to study in university education. This interesting course is very practical and makes use of testing equipment in the materials laboratory.

Mechanical testing of industrial products and components is essential to ensure their load-bearing, fatigue resistance, and impact resistance, directly preventing production accidents and ensuring stable operation of equipment. UnitedTest can cover a full range of tests including tensile, hardness, and fatigue, complying with national and international standards, and provides customized industrial mechanical testing solutions.

Mechanical testing in the plastic pipe industry determines ring stiffness, impact resistance, and tensile performance, directly preventing pipe bursts and deformation risks. UnitedTest can cover full-dimensional mechanical testing of pipes, complies with ISO,ASTM,EN et.c, international standards, and provides customized testing solutions.

In the construction engineering and building materials industry, mechanical testing determines the compressive and tensile properties of materials such as concrete and steel, which is core to ensuring the safety and durability of buildings. UnitedTest can cover the full range of building material mechanical tests, complies with ISO, ASTM international standards, and provides customized testing solutions for compressive, tensile, and other properties.

Mechanical testing in the food and beverage industry involves the compressive and tensile performance of packaging and the safety of food texture, directly ensuring storage, transportation safety, and the eating experience. UnitedTest can cover all-dimensional mechanical testing for packaging and food texture, comply with national and international standards, and provide customized testing solutions.

Mechanical testing in the packaging industry determines the packaging's resistance to compression, impact, and tension, directly ensuring the safety of contents during storage and transportation. UnitedTest can cover comprehensive mechanical testing for packaging, complying with ISO, ASTM Standards, and provides customized testing solutions for compression, drop, tear, and more.

Mechanical testing in the transportation industry concerns the load-bearing and fatigue resistance performance of core components such as vehicles, tracks, and containers, directly ensuring transport safety and equipment durability. UnitedTest can cover mechanical testing for all types of transportation materials, complying with national and international standards, and provides customized testing solutions including tensile, fatigue, and impact tests.

Metallurgical testing examines the properties of metallic materials to determine if a particular metal is appropriate for its intended use.

Testing of polymer materials covers mechanical, thermal, and chemical properties, verifying strength, heat resistance, composition, and ensuring product quality and compliance.

UnitedTest offer world-class testing solution in testing for polymeric materials, including elastomers, thermoplastics, composites, coatings, and structural adhesives in a variety of industries.

Testing of rubber and elastomers is used to assess the various properties and performance of materials under different conditions. This is crucial for ensuring the safety, functionality, and quality of rubber and elastomer products used in industries such as automotive, construction, consumer goods, and aerospace.

Conduct adhesive testing using various testing methods to determine their performance and characteristics in applications across multiple industries such as aerospace, automotive, construction, packaging, industrial, medical, and energy, thereby supporting application development and quality assurance.

UnitedTest supply machine and testing solution for tension, compression, fracture toughness, direct shear, triaxial and ultrasonic velocity are common concrete and rock testing applications.

UnitedTest has helped a number of companies involved in the wood, paper, cardboard, and corrugated industry with their testing needs. Our materials testing systems are capable of testing raw materials, components, and finished products.

UnitedTest testing system is trusted by leading medical device manufacturers, universities, and medical research laboratories worldwide. Whether testing tissues or bioresorbable materials, stents, or sutures, UnitedTest offers a variety of single-actuator and dual-actuator systems to meet your biomedical testing needs.

Mechanical testing in the textile fabric industry determines core properties such as fabric tensile strength, tear resistance, and wear resistance, directly affecting product durability and safety. UnitedTest can cover comprehensive mechanical tests for textiles, complying with national standards / ISO standards, and provides customized testing solutions including tensile, tear, and puncture tests.

The mechanical testing of industrial components directly determines the load-bearing, fatigue resistance, and wear resistance of the parts, helping to avoid equipment failure risks. UnitedTest can cover a full range of tests including tensile, hardness, and fatigue, is compatible with ISO/ASTM/GB standards, and provides customized mechanical testing solutions for industrial components.

Mechanical testing in the glass-ceramics industry determines core properties such as flexural strength, hardness, and fracture toughness, directly helping to avoid brittleness and failure risks. UnitedTest can cover comprehensive testing for flexural strength, hardness, and fracture toughness, compatible with national and ISO/ASTM standards, and provides customized testing solutions.

Tensile test evaluates material resistance to stretching, measuring strength/elongation critical for quality control. UnitedTest offers universal tensile testers (10-600KN) compliant with ASTM/ISO standards, providing tailored solutions for metals, polymers, medical & industrial materials.

Compression test assesses material resistance to compressive loads, measuring strength/deformation critical for quality validation. UnitedTest offers compression testing machines compliant with ASTM/ISO standards, providing tailored solutions for concrete, plastics, metals and industrial components.

Flexural & Bend tests evaluate material resistance to bending forces, measuring strength, stiffness and ductility for quality assurance. UnitedTest provides flexural testing machines (3-point/4-point bend) compliant with ASTM/ISO standards, offering tailored solutions for composites, plastics, metals and construction materials.

Torsion Test evaluates material resistance to rotational forces, measuring torsional strength/ductility critical for fasteners, insulators, shafts. UnitedTest offers torsion testers compliant with ASTM A938/ISO 16047, providing tailored solutions for automotive, aerospace, fastener industries.

Fatigue Test assesses material durability under cyclic loading, critical for predicting service life of industrial components. UnitedTest offers fatigue testing systems (axial/bending/torsion) compliant with ASTM E466/ISO 12106, providing tailored solutions for automotive, aerospace and manufacturing sectors.

Peel Test measures material adhesion strength by evaluating resistance to peeling forces, critical for adhesives, films, packaging. UnitedTest offers peel testers compliant with ASTM D903/ISO 8510, covering 90°/180° peel tests, and tailored solutions for packaging, automotive, textile industries.

Impact Test evaluates material resistance to sudden shock loads, critical for assessing toughness and fracture risk. UnitedTest offers impact testers (Charpy/Izod/fall weight) compliant with ASTM E23/ISO 148, providing tailored solutions for metals, plastics, glass and industrial components.

Tear & Shear Test evaluates material resistance to tearing and shearing forces, measuring critical strength parameters for quality control. Tear tests (Elmendorf/trouser/trapezoidal) assess resistance to crack propagation in films/fabrics, while shear tests measure resistance to parallel forces in joints/bolts. UnitedTest provides universal testing machines (10KN-600KN) with specialized fixtures for both tests, compliant with ASTM D624/D3164 and ISO standards, serving automotive, packaging and construction industries.

Hardness test measures material's resistance to permanent indentation, critical for quality control. UnitedTest offers universal hardness testers (Rockwell/Brinell/Vickers) compliant with ASTM/ISO standards, plus tailored hardness testing solutions for diverse industrial needs.

Biaxial/triaxial tests evaluate material performance under multi-axis loads, critical for biomaterials, metals and composites. UnitedTest provides compliant testing machines (ASTM/ISO) for planar biaxial, static/fatigue triaxial tests, with tailored solutions for industrial & biomedical needs.

Friction and wear tests assess material resistance to friction, abrasion and wear, critical for industrial material performance validation. UnitedTest offers tribometers compliant with ASTM G99/ISO standards, covering pin-on-disk, four-ball tests, and tailored friction & wear testing solutions for diverse industries.

Pressure test evaluates material/component resistance to static/dynamic pressure, critical for sealing, strength and safety validation. UnitedTest offers pressure testing machines compliant with ASTM/ISO standards, covering burst, hold-pressure tests, and tailored solutions for industrial, automotive & medical sectors.

Fire test assesses material flammability, heat resistance and fire-retardant performance, critical for safety compliance across industries. UnitedTest offers fire testing equipment compliant with ASTM/ISO/UL standards, providing tailored fire test solutions for building materials, plastics and industrial components.

Non-destructive Test (NDT) evaluates material/component integrity without damage, critical for safety & quality across industries. UnitedTest offers ultrasonic/X-ray/magnetic particle NDT equipment compliant with ASTM/ISO standards, plus tailored NDT solutions for aerospace, automotive & manufacturing sectors.

ISO 2505 Thermoplastic Pipe Longitudinal Reversion Tester | UnitedTest

UnitedTest is a professional manufacturer of ISO 2505 longitudinal reversion testers, designed to deliver accurate dimensional stability testing for thermoplastic pipes in compliance with the latest international standard requirements.

ISO 2505 specifies standardized test methods and technical parameters to evaluate longitudinal reversion — the heat-induced length change of thermoplastics pipes. The standard authorizes two reliable heating mediums for laboratory testing: heated liquid bath and air oven, enabling flexible and professional thermal performance evaluation for various plastic pipe products.

Updated version of ISO 2505 expands its applicable material scope, covering mainstream advanced pipe materials including PE 100-RC, PB-H, PB-R, PE-RT, PP-RCT and PE-UHMW. This test effectively assesses thermal deformation resistance and structural stability, serving as essential quality control and material verification criteria for thermoplastic pipe manufacturing.

Our UnitedTest ISO 2505 pipe reversion tester fully complies with updated 2023 standard rules, supporting both heating test modes and delivering consistent, repeatable longitudinal reversion test data for industrial pipe R&D and batch quality inspection.

The longitudinal Reversion rate of pipe materials refers to the percentage change in length of thermoplastic pipe materials under specific temperatures, used to assess the thermal contraction properties of the material. The measurement method is based on the national standard ISO 2505, GB/T 6671-2001, (TCVN 6148 standard equivlent with ISO 2505).

Test Principle

Thermoplastic pipes retain internal residual stress generated during extrusion and cooling. When exposed to controlled high temperature, internal stress releases and causes permanent length contraction (or minor elongation). The test principle follows three core steps:

1, Mark a fixed reference length on conditioned pipe specimens and measure the original distance L0 at standard ambient temperature 23±2°C;

2, Heat specimens in a temperature-controlled liquid bath or air oven for material & wall-thickness specified duration to fully release residual stress;

3, Cool specimens back to 23±2°C, re-measure the marked length L1, calculate length change ΔL = L0-L1;

ISO 2505 Thermoplastic Pipes Longitudinal Reversion Test (PF Heat Reversion Test)

Testing Methods

Method A (Liquid Bath Test): The sample is immersed in an inert liquid (such as glycerin or silicone oil) at 150±2°C. The insulation time is calculated based on the wall thickness (usually 1 min/mm). After cooling, the change in length is measured. This method is suitable for small-diameter pipes.

Method B (Air Oven Test): The sample is placed horizontally in an oven, with the temperature set according to the material type (e.g., 150±2°C for PVC, 110±2°C for PP). The time is also calculated based on the wall thickness, and after cooling, the length is measured.

This method is suitable for all pipe materials; large-diameter pipes need to be cut into four pieces for testing. Influencing FactorsThe longitudinal retraction rate is mainly influenced by the type of material, processing technology (such as extrusion speed and cooling rate), and wall thickness. UPVC pipes must be strictly controlled within standard limits (usually ≤5%) to ensure stability in use.

Test Specimen Information

Standard specimen length: 200±20mm; minimum marked test distance between two circumferential lines: 100 mm; minimum overall test length 180 mm;

Sample quantity: minimum 3 identical specimens per pipe batch for final average calculation;

Special rule for DN ≥250 mm large-diameter pipes: cut each specimen into four equal axial segments, test all 12 segments from three specimens; the maximum reversion among four segments represents one specimen’s result.

Test Equipment of ISO 2505 Thermoplastic Pipes Longitudinal Reversion Test (PF Heat Reversion Test)

Recommend UnitedTest Longitudinal Reversion Tester (PF Heat Reversion Test Apparatus) for testing Pipes

Thermostatically controlled liquid bath	with volume and agitation to sustain uniform temperature during immersion;
Thermostatic air oven	rapid temperature recovery, ±2°C temperature deviation tolerance;
Specimen holding fixtures	hangers or low-friction horizontal supports;
Scriber	to engrave clear circumferential axial reference marks on pipe outer surface
Vernier calliper	measurement uncertainty ≤0.1 mm for length reading;

Core Test Parameters

Material Group	Test Temperature T_R
PVC-U, PVC-C, PVC-HI, SAN+PVC, PP-H, PP-B	150±2°C
PP-R, PP-RCT, ASA	135±2°C
PE32/40, PE50/63	100±2°C
PE80, PE100, PE100-RC, PB-H, PB-R, ABS, PE-UHMW	110±2°C
PE-RT, PE-X	120±2°C
PA-U (only air oven permitted)	150±2°C

Wall thickness upper limit: only applicable for pipes with e<16mm;

Heating duration strictly determined by wall thickness and test method (liquid bath / air oven);

Full Standard Test Procedures

Pre-measurement at 23±2°C: record original marked length L0 with precision ≤0.25 mm;

Preheat liquid bath or air oven to material-specified T_R, stabilize temperature fully before loading specimens;

Load specimens freely without contact with equipment walls; maintain ≥30 mm liquid submersion depth for bath testing;

Start timing only after equipment recovers target temperature; hold for required exposure time;

Remove specimens and cool in the same orientation inside the bath/oven environment to avoid forced deformation;

After natural cooling to 23±2°C, hold for extra minimum 1 h to stabilize dimensions;

Measure maximum and minimum marked distances across diametric opposite sides, following pipe surface curvature;

Record visual defects (bubbles, cracking, discoloration) as failure evidence regardless of reversion percentage.

Recommended Maximum Reversion Limits

Material	Maximum Allowable Reversion
PVC-U, PVC-C, PVC-HI, SAN+PVC, ABS, ASA	<5%
All PE grades (PE32 to PE-UHMW), PE-RT, PE-X, PA-U	<3%
PB-H, PB-R, PP-H, PP-B, PP-R, PP-RCT	<2%

Test Application & Industry Fields

1 Applicable Pipe Scope

Eligible pipes: smooth inner & outer wall thermoplastic pipes with uniform constant cross-section, wall thickness <16 mm;

Excluded pipes: structured-wall corrugated plastic pipes (non-smooth surface).

2 Covered Thermoplastic Materials

PVC-U, PVC-C, PVC-HI, SAN+PVC, PA-U, all PE series (PE32/40/50/63/80/100/100-RC, PE-RT, PE-X, PE-UHMW), PB-H/PB-R, PP-H/PP-B/PP-R/PP-RCT, ABS, ASA.

3 Industrial Application Scenarios

Municipal water supply & drainage pipelines (PE, PP, PVC pressure & gravity pipes);

Domestic hot/cold plumbing systems (PP-R, PB, PE-RT, PE-X);

Industrial fluid transport plastic piping;

Irrigation plastic pipeline systems;

Factory incoming raw material inspection, extrusion production quality control, third-party product certification;

Engineering design and on-site material acceptance testing for thermal dimensional stability assessment.

Related Test Standard:

ISO 2505	Thermoplastics pipes — Longitudinal reversion — Test method and parameters
ISO 2506	Polyethylene pipes (PE); Longitudinal reversion; Test methods and specification
EN 743	Plastics Piping and Ducting Systems - Thermoplastics Pipes - Determination of the Longitudinal Reversion
TCVN 6148	Thermoplastics pipes.Longitudinal reversion.Test method and parameters
GB/T 6671	Thermoplastics pipes-Determination of longitudinal reversion
ISO 3478	Polypropylene (PP) pipes; Determination of longitudinal reversion
ISO 3480	Polypropylene (PP) pipes; Maximum permissible longitudinal reversion
JIS K 6814-1	Thermoplastics pipes -- Longitudinal reversion -- Part 1: Determination methods
NBN T 42	Plastic pipes - Determination of longitudinal reversion after heating

Keywords: UnitedTest ISO 2505 longitudinal reversion tester, thermoplastic pipe dimensional stability test machine, ISO 2505 2023 updated pipe testing equipment, PE100-RC PE-RT PP-RCT PE-UHMW thermal reversion tester, heated liquid bath air oven pipe heat deformation test, thermoplastic pipe longitudinal reversion test per ISO 2505, heat induced length change testing for plastic pipes, ISO 2505 new material pipe thermal stability test, PE 100-RC and PP-RCT pipe thermal deformation tester, air oven & liquid bath thermoplastic pipe reversion testing equipment, industrial thermoplastic pipe dimensional change quality control tester

Pipe Size Change Measuring Tester/ Longitudinal Reversion Tester suitable to measure various kinds of plastic pipe or plastic materials size change after heating, or used to heat the test sample. It can be used as a heating oven as well.

Q1: What is ISO 2505 used to test exactly?

A1: It measures the longitudinal thermal reversion (thermal shrinkage) of smooth-wall thermoplastic pipes after controlled heating. It quantifies the percentage length change caused by releasing residual extrusion stress, and also checks surface damage like cracks or bubbles after heating. It only applies to uniform smooth-wall pipes with wall thickness e < 16 mm, not structured corrugated pipes.

Q2: What is the difference between ISO 2505:2023 and the old 2005 version?

A2: Two major technical updates:

Added test temperature/parameter rules for six new pipe materials: PE 100-RC, PB-H, PB-R, PE-RT, PP-RCT, PE-UHMW;

New mandatory rule: coiled small-diameter pipes must be fully straightened before marking specimens for testing.

All other core test principles and calculation formulas remain unchanged.

Q3: Which two heating methods are allowed by ISO 2505, and which one takes priority during disputes?

A3: Liquid heating bath and circulating air oven.

Heated liquid bath is the reference arbitration method if test results from the two methods conflict;

Air oven is an alternative method for factory routine quality control, with longer holding time required.

Q4: Why do coiled pipes need straightening before marking?

A4: Coiled pipes have permanent bending curvature from winding. If tested without straightening, residual bending stress overlaps thermal shrinkage stress, leading to inaccurate, artificially high reversion values that do not reflect real pipe performance. Straightening removes bending stress to ensure only extrusion residual stress is measured.

Q5: How many test specimens do we need for one pipe batch? What about DN ≥250 mm large pipes?

A5: Minimum 3 full specimens (200±20 mm each) per batch normally.

For pipes with nominal diameter ≥250 mm, cut each specimen into four equal axial segments (12 segments total). The maximum reversion of four segments represents one specimen’s result, then average the three specimen values for the final report.

Q6: What is the standard conditioning time before testing, and why is conditioning required?

A6: Conditioning at 23±2°C depends on wall thickness e:

e < 3 mm: 1 h

3 mm ≤ e < 8 mm: 3 h

8 mm ≤ e < 16 mm: 6 h

Conditioning stabilizes specimen temperature and eliminates temporary dimensional fluctuations caused by transport, cutting or storage temperature changes, ensuring consistent initial length measurement L0.

Q7: What liquids are acceptable for the heating bath? Are there forbidden liquids?

A7: Approved media: glycerine, glycol, aromatic-free mineral oil, calcium chloride water solution.

Forbidden liquids: solvents that dissolve, swell or chemically degrade thermoplastics (e.g., aromatic oil, ketones, strong acids). The liquid must stay stable without decomposition at the target test temperature TR.

Q8: Why do liquid bath and air oven have different exposure durations for the same pipe wall thickness?

A8: Liquid transfers heat much faster and more uniformly to the pipe wall than air convection. Therefore liquid bath uses shorter soak time (15/30 min), while air oven requires longer heating (60/120 min) to fully release internal residual stress across the full pipe wall.

Q9: The pipe shows tiny bubbles or surface cracks after heating — does the test fail even if reversion percentage meets the limit?

A9: Yes. ISO 2505 requires no surface appearance change after heating. Bubbles, cracking, blistering or discoloration indicate material degradation or poor formulation, which counts as a failed test regardless of reversion value.

Q10: Why is the ISO 2505 longitudinal reversion test critical for plastic pipes?

A10: Four key reasons:

Detect extrusion defects: Excessive shrinkage signals uneven cooling, mismatched haul-off speed or incomplete stress relief during pipe production;

Predict in-service thermal performance: Pipes carrying hot water or laid in hot soil will shrink naturally; high reversion causes joint pull-out, leakage and pipeline breakage;

Validate new material formulations: Modified grades (PE100-RC, PP-RCT) rely on this test to prove low-shrinkage performance;

Global uniform quality benchmark: Standardized test rules eliminate cross-border testing discrepancies for trade certification and quality dispute resolution.

Q11: What real pipeline failures can high longitudinal reversion cause in construction?

A11: During seasonal temperature cycles or continuous hot fluid transport, over-shrinking pipes pull pipe fittings apart, create gaps at joints, trigger water/gas leakage, and even crack pipe bodies. Installers must design expansion compensation joints based on reversion data from ISO 2505 to avoid these failures.

Q12: Which pipes cannot be tested by ISO 2505?

A12: Two main excluded categories:

Structured-wall / corrugated plastic pipes with non-smooth inner/outer surfaces;

Thermoplastic pipes with average wall thickness e ≥ 16 mm.

Q13: Can this test be used for cross-linked polyethylene (PE-X) pipes?

A13: Yes. ISO 2505:2023 lists PE-X with a specified test temperature of 120±2°C and recommended maximum reversion <3%. It verifies cross-link uniformity and residual stress after PE-X pipe manufacturing.

Q14: Why do replicate specimens from the same pipe produce inconsistent reversion results?

A14: Common root causes:

Coiled pipe segments not fully straightened before marking;

Specimens touched oven/bath walls during heating, restricting free shrinkage;

Insufficient cooling holding time (less than 1 hour after cooling to 23°C);

Uneven liquid bath temperature with poor circulation.

We offer customization to meet your specific needs. Our expert team will collaborate with you to develop the perfect product for you