Information on the most widely used ASTM standards within the materials testing industry
EN 1393 GRP Pipe Initial Longitudinal Tensile Properties Tester | UnitedTest
EN 1393 specifies test procedures for initial longitudinal tensile properties of GRP pipes, covering longitudinal modulus of elasticity with three available test methods. Compare against ISO 8513 requirements. UnitedTest manufactures EN 1393‑compliant GRP pipe tensile testing machines for composite pipe labs and quality control.
EN 1393 — Plastics piping systems — Glass‑reinforced thermosetting plastics (GRP) pipes — Determination of initial longitudinal tensile properties
EN 1393 defines standardized laboratory procedures to measure the initial longitudinal (axial) tensile behaviour of GRP pipes, focusing on axial performance rather than hoop strength of glass‑reinforced thermosetting plastic piping components. This European standard features three distinct test methods and supports measurement of the longitudinal modulus of elasticity, alongside tensile strength and ultimate elongation data for GRP pipe specimens.
There is an important technical distinction between EN 1393 and ISO 8513: ISO 8513 keeps only Methods A and B and removes modulus evaluation capability, while EN 1393 retains all three test approaches and enables modulus of elasticity testing, making it valuable for detailed material characterization for GRP pipe development, certification and engineering design.
UnitedTest designs and produces high‑precision EN 1393 compliant GRP pipe tensile testing machines, supporting full‑range axial tensile property measurement including longitudinal modulus, tensile strength and break elongation for fiberglass‑reinforced polyester, epoxy and vinylester pipes. Our test equipment serves composite pipe manufacturers, third‑party test laboratories and civil‑engineering pipeline research projects.
Test Principle
A prepared GRP specimen (strip / full pipe / notched plate) is axially loaded at constant cross‑head speed until fracture occurs within 1–3 minutes.
Raw test outputs: maximum breaking force, strain/elongation data from extensometer (not cross‑head displacement for modulus).
All tensile properties (longitudinal tensile strength, ultimate elongation, modulus) are computed using initial specimen geometry dimensions.
Important note: Cross‑head movement cannot be used for modulus calculation due to unavoidable small grip slippage. External extensometer must be attached directly to the specimen gauge section for modulus and precise elongation.
Three Specific Test Methods & Application Scope
| Method A: Longitudinal Strip Specimen Test | Specimen: Dumbbell‑shaped or parallel‑sided strip cut longitudinally from GRP pipe wall. Application: DN ≥ 50 circumferentially‑wound / centrifugally‑cast GRP pipes; DN ≥ 200 helically‑filament‑wound pipes. Usage note: Parallel‑sided strips are allowed for minimum‑property compliance testing and for pipes DN > 400. |
| Method B: Full Pipe Section Test | Specimen: Complete circular pipe segment preserving full cross‑section. Minimum length = greater value between 450 mm or four times DN in mm. Application: All GRP pipe types, commonly used for DN up to DN 300. |
| Method C: Notched‑plate specimen test | Specimen: Square notched plate machined from pipe wall, with controlled neck notch geometry. Application: Primarily for helically‑wound pipes with winding angle not near 90°, also usable for other GRP pipe constructions. The notch forces fracture to occur at the neck region of the plate specimen. |
Test Specimen
| Method A strip specimens | Overall length: 300 ± 15mm
Built‑up‑end preparation: Specimen ends may be thickened by thermosetting resin / reinforced resin, then machined flat and parallel to align specimen centroid with machine load axis.
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| Method B full‑pipe‑section specimens | Full circular pipe piece; minimum length = max(450 mm, 4 × DN). Measure internal/external diameter and wall thickness at three equally spaced circumferential positions on both pipe ends for calculating mean diameter dm. |
| Method C notched‑plate specimens | Cut from pipe wall with correct reinforcement orientation.
Specimen ends are resin‑built‑up; flash removed. Measure winding‑angle θ with ±1° accuracy.
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Test Equipment of EN 1393 GRP pipes Initial longitudinal tensile test
| Universal Testing Machine (UTM) | Fixed and moving cross‑head with grips to guarantee perfect axial alignment between specimen and tensile‑load direction. Constant cross‑head drive speed; test duration shall be controlled so rupture occurs within 1 min‑3 min. Force‑measurement accuracy: within ±1 % of measured value, low inertia lag. |
| Specialized Grips | Grips must hold specimens without slipping or crushing damage. Self‑tightening automatic grips are acceptable. For Method B full‑pipe sections: segmented wedge grips with internal mandrel and reinforcing bands. For Method C notched‑plate samples: fixtures matching plate geometry; specimen ends often resin‑built‑up. |
| Dimension‑measuring devices | Measurement‑instrument accuracy shall be half the required measurement tolerance (e.g. ±0.05 mm instrument for ±0.1 mm measurement). Measures wall thickness, width, diameter, notch radius, winding‑angle θ. |
| extensometer / strain gauge | Mandatory only if elongation or modulus of elasticity is required. Cross‑head travel alone cannot be used to calculate modulus because grip slippage creates measurement error. Accuracy: ±1 % of indicated value. Strain gauges shall be mounted on both specimen sides and average values used for modulus calculation. |
Mandatory Test Parameters & Stipulations:
| Loading | Constant cross-head speed; rupture in 1–3 min |
| Force record | Maximum force in newtons; force–elongation if elongation/modulus required |
| Alignment | Longitudinal axis coincident with pull direction |
| Grips | Uniformly and tightly clamped to prevent slip |
| Rejected specimens | Slipped in grips or ruptured outside gauge length → discard and repeat |
| Modulus measurement | Requires extension indicator; grip movement not acceptable |
For modulus, strain must be measured on the specimen, not inferred from cross-head travel.
Built-up ends are used when grip pressure would damage the specimen or when parallel loading centerline alignment must be ensured.
Step-by-Step Test Procedure of EN 1393 GRP pipes Initial longitudinal tensile test
Common procedure for Methods A, B, C
Condition specimen at test temperature ≥ 0.5 h.
Measure dimensions:
Method A: width b or b_G at center of gauge length, to 0.1 mm
Method B: internal or external diameter + average wall thickness from 3 equally spaced measurements at both ends
Method C: width b to 0.1 mm, winding angle θ to ±1°, neck radius r
Mount in tensile machine; align axially with load direction.
Clamp grips uniformly and tightly.
If needed, attach extension indicator for elongation/modulus.
Load at constant cross-head speed so fracture occurs in 1–3 min.
Record force–elongation data and maximum force.
Discard slips or non-gauge failures; repeat with replacement specimens.
Calculate strength, elongation, modulus per method.
Industry Fields & Applications
EN 1393 applies to European GRP‑pipe manufacturing, quality‑control, certification and third‑party‑testing laboratories for these sectors:
1. Municipal engineering: Sewer, drainage, drinking‑water supply GRP pipelines
2. Chemical‑process industry: Corrosive‑media FRP piping
3. Agriculture: Large‑diameter irrigation transmission pipes
4. Oil & gas non‑metallic underground gathering pipelines
5. Off‑shore / marine low‑pressure fluid piping
6. Construction building wastewater and fire‑protection piping
7. Composite‑material R&D laboratories and notified‑body certification labs across EU member states.
It serves factory quality‑control, third‑party product certification, and pipeline‑design input for European GRP‑pipe projects.
Related Test Standard:
| ISO 8513 | Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes — Test methods for the determination of the initial longitudinal tensile strength |
| EN 1394 | Companion European standard for circumferential (hoop) tensile properties of GRP pipes. |
| EN 1393 | Glass-reinforced thermosetting plastics (GRP) pipes - Determination of initial longitudinal tensile properties |
| JIS K 7033 | Plastics piping systems -- Pipes made of glass-reinforced thermosetting plastics (GRP) -- Determination of initial tensile properties |
| ASTM D2105 | Standard Test Method for Longitudinal Tensile Properties of “Fiberglass” (Glass-Fiber-Reinforced Thermosetting-Resin) Pipe and Tube |
| ISO 527-4/ISO 527-5 | Plastics – Tensile properties – Part 4: Test conditions for isotropic/orthotropic fiber-reinforced plastic composites Plastics – Tensile properties – Part 5: Test conditions for unidirectional fiber-reinforced plastic composites |
| EN 1796 | European product standard for GRP pipes that cites initial longitudinal tensile strength requirements; design basis for safety factors. |
| EN 14364 | GRP piping for drainage and sewerage, references similar property data. |
BS 2782 Part 12 Methods 1210A–C | UK Standards: Plastics piping systems. Glass-reinforced thermosetting plastics (GRP) pipes. Determination of initial longitudinal tensile properties |
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Related products and device
Related Standard
ISO 8513 Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes — Test methods for the determination of the initial longitudinal tensile strength
ISO 8513 measure two core longitudinal tensile properties of glass-reinforced thermosetting plastic (GRP, also known as fiberglass-reinforced plastic FRP) pipes: Initial longitudinal tensile strength, Percentage ultimate elongation. IT only addresses tensile strength and break elongation; it explicitly excludes longitudinal tensile modulus testing, as multi-layer GRP pipe wall structures make precise strain measurement impractical.
ASTM D2105 Standard Test Method for Longitudinal Tensile Properties of "Fiberglass" (Glass‑Fiber‑Reinforced Thermosetting‑Resin) Pipe and Tube
ASTM D2105 determine the comparative longitudinal tensile properties of a fiberglass pipe specimen by pulling it in axial tension to failure under defined conditioning, temperature, and machine‑crosshead‑speed conditions.
ISO 527-4 and ISO 527-5 are two key standards within the ISO 527 series for determining the tensile properties of fibre-reinforced plastic composites.
ISO 527-4 covers the general principles and tests for isotropic and orthotropic materials. ISO 527-5 provides specific procedures for testing unidirectional fiber-reinforced composites.
These standards are critically important because they provide a unified, reliable method to measure fundamental mechanical properties (like tensile strength, modulus, and strain) which are essential for material selection, quality control, structural design, and R&D in aerospace, automotive, wind energy, and sports equipment industries.
ASTM D4521 is specifically for corrugated fiberboard (corrugated cardboard) and solid fiberboard used in packaging. It measures only the static (starting) coefficient of friction — not kinetic/sliding COF.
ASTM D1037 - Standard Test Methods for Evaluating Properties of Wood-Base Fiber and Particle Panel Materials
ASTM D1037 test methods cover the determination of the properties of wood-base fiber and particle panel materials that are produced as mat-formed panels such a particleboard, medium density fiberboard, hardboard, and oriented strand board.
ASTM D1037 test methods cover small-specimen tests for wood-base fiber and particle panel materials that are made to provide: Data for comparing the mechanical and physical properties of various materials,
Data for determining the influence on the basic properties of such factors as raw material and processing variables, post-treatments of panels, and environmental influences, and
Data for manufacturing control, product research and development, and specification acceptance.
ISO 14125 is a test method to determine flexure properties of fiber-reinforced plastic composites.
There are two methods used, Method A for a three-point flexure test and Method B for a four-point flexure test.
There are four material classes, Class I – IV, which define the specimen length, span, width, and thickness.
The standard requires deflection measurement not exceed +/- 1% error of full scale.
ISO 14125 is based on the ISO 178 standard and both utilize three point flexural testing of a freely supported bar loaded between the supports.
ISO 14125 focuses on fibre reinforced plastic compositesand has an alternative 4-point loading testing procedure, Procedure B.
The material properties recorded by following the standard are the flexural stress, flexural strain, elastic modulus in flexure and interlaminar shear modulus.
Compression-testing machine which will comply with ISO 5893 and shall be capable of maintaining speeds of (0.5 +- 20 %) mm/min to (500 +- 10 %) mm/min.
ISO 14126 Compression test Fibre-reinforced plastic composites — Determination of compressive properties in the in-plane direction
The ISO 14126 and ASTM D3410 standards describe the shear loading compression test on composites. The objective of this standard test method is the determination of compressive properties in laminate planes.
For this method, the compression force is transmitted via shear forces to the specimen, which is secured in the test fixture and usually includes cap strips. Homogeneous stress distribution is achieved if there is sufficient grip-to-grip separation in the unsupported center area of the specimen.
One of the benefits provided is axial guidance of the specimen during the test, as well as the elimination of force application via the end faces. This eliminates the need for high-precision preparation of the specimen end faces.
EN 1393 GRP Pipe Longitudinal Tensile Test FAQs (Q&A Format)
Q1: What is EN 1393:1996 and why is this test important for GRP pipes?
A1: EN 1393:1996 is the European CEN standard for glass‑reinforced thermosetting plastic (GRP / FRP) pipe longitudinal tensile testing. It defines three test methods to measure initial longitudinal tensile strength, ultimate elongation, and longitudinal modulus of elasticity.
This test is critical for these reasons:
1. European project compliance: GRP pipe projects across EU countries require EN 1393 test reports for factory production control and tender acceptance.
2. Full elastic material data: Unlike ISO 8513, EN 1393 outputs longitudinal modulus, which is essential for structural design of buried pipelines under soil loads, thermal expansion and bending deformation.
3. Helical‑wound pipe evaluation: Unique Method C notched‑plate specimen solves testing challenges for pipes with non‑90° winding angles.
4. Manufacturing quality verification: Tensile strength, elongation and modulus are highly sensitive to fiber content, winding accuracy, resin curing and laminate lay‑up; the test detects defects like voids, poor fiber wet‑out or delamination before pipe field installation.
Q2. Which industries use EN 1393?
A2: Water supply and potable water, sewerage and drainage, marine and offshore cooling/intake/discharge lines, oil and gas, chemical process piping, power-plant cooling systems, fire-protection GRP systems, and civil infrastructure such as buried pipes, anchors, thrust blocks, and submarine outfalls.
Q3: What is the main difference between EN 1393 and ISO 8513?
A3: 1. EN 1393 has three test methods (A/B/C); ISO 8513 only retains Method A and B and removes Method C completely.
2. EN 1393 explicitly supports longitudinal modulus calculation, and requires extensometer for modulus measurement; ISO 8513 excludes modulus testing due to measurement difficulty for multi‑layer pipe walls.
3. EN 1393 controls test duration: rupture must take place 1‑3 minutes; ISO 8513 uses fixed cross‑head speed 2‑5 mm/min.
4. EN 1393 is European regional standard; ISO 8513 is global international standard. National EU standards such as BS‑EN 1393, DIN‑EN 1393 are national transpositions of EN 1393.
Q4: Can I use cross‑head displacement data to calculate modulus for EN 1393?
A4: No, strictly forbidden. Minor grip slippage and machine tolerance create measurement error. Modulus and precise elongation must use readings from an external extensometer or dual‑side mounted strain gauges directly attached to specimen gauge length. Cross‑head travel can only be used for simple break‑force tests, not modulus calculation.
Q5. Why can Method A, B, and C give different numbers?
A5: They introduce load differently: a strip localizes stress in a cut specimen; a full pipe section loads the whole cross-section; a notched plate introduces a winding-angle correction and notch stress concentration. Each is valid for its purpose, but not directly interchangeable.
Q6: What testing machine fulfils full EN 1393 compliance? Can UnitedTest supply this equipment?
A6: Mandatory hardware requirements for EN 1393:
1. Constant‑rate universal tensile testing machine with force accuracy ≤±1 % reading, low inertia lag.
2. Full fixture kits for Method A strip, Method B full‑pipe segmented mandrel grips, **special fixtures for Method C notched‑plate specimens**.
3. High‑precision extensometer / strain‑gauge acquisition module for modulus measurement (cannot rely only on cross‑head movement).
4. Software pre‑programmed with EN 1393 calculation formulas for strength, elongation and modulus.
UnitedTest is a professional manufacturer delivering fully EN 1393‑compliant GRP longitudinal tensile testing machines:
- Complete fixture portfolio: flat grips for Method A strips; segmented mandrel grips for Method B full pipe sections; dedicated clamping fixtures for Method C notched‑plate specimens.
- High‑precision extensometer channel for modulus calculation, strictly avoiding cross‑head‑displacement‑based modulus error.
- Servo drive system adjustable to achieve required rupture time window of 1‑3 min.
- Built‑in EN 1393 calculation engine; auto‑generate audit‑ready EN 1393 test reports.
- Custom load capacity from 10 kN‑600 kN for DN 50‑DN 300 GRP pipes.
Q7: Why Choose UnitedTest for EN 1393 Testing?
A7: UnitedTest is a professional manufacturer of EN 1393:1996 compliant GRP / FRP pipe longitudinal tensile testing machines, supporting all three test methods Method A, Method B and Method C defined in European standard EN 1393 for glass‑reinforced thermosetting plastic piping systems.
Unlike generic universal testers, our EN 1393 tensile system supports complete property measurement: initial longitudinal tensile strength, percentage ultimate elongation and longitudinal modulus of elasticity. A high‑precision extensometer module is integrated to avoid common modulus calculation errors caused by grip slippage and cross‑head displacement misuse.
Our full fixture package includes:
1. Flat reinforced grip fixtures for Method A dumbbell / parallel‑sided strip specimens;
2. Segmented wedge mandrel grips for Method B full‑cross‑section GRP pipe segments (up to DN 300);
3. Dedicated clamping fixtures for Method C notched‑plate specimens, specially for helically‑wound GRP pipes with non‑90° winding angles.
The servo closed‑loop drive system allows adjustable cross‑head speed so specimen rupture falls within the mandatory 1‑3 min test duration specified by EN 1393. Test software pre‑loads all EN 1393 calculation formulas, auto‑computes strength, elongation and modulus, and exports complete audit‑ready test reports matching EN 1393 clause 10 reporting requirements.
Available load capacities cover 10 kN to 600 kN. UnitedTest supplies complete lab solutions for European GRP pipe factories, third‑party accredited test laboratories, chemical pipeline producers, municipal drainage FRP pipe manufacturers and composite‑material research institutes. Our machines also support ISO 8513 testing, and can pair with ring stiffness testers and hydrostatic burst testers for full‑range GRP pipe laboratory setup. CE certified, global technical support and factory‑direct supply.
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