Knowledge of the mechanical properties of pipes made of thermoplastics or fibre composites is of great importance for their use as drinking water pipes, wastewater pipes, in irrigation systems or gas pipelines, as they are exposed to high pressure loads in all application scenarios. In order to withstand these loads, there are a number of component tests that are used to check the ring stiffness and ring flexibility of the pipes as well as the welded joints of the pipe segments.
Ring stiffness describes the resistance of a pipe to deformation caused by a vertically acting force. It is determined by measuring the force and deformation of the pipe at a constant deformation speed in accordance with DIN EN 9969.
The ring flexibility is determined in accordance with DIN EN ISO 13968 by determining the bending radius at which the pipe exhibits a defined deformation. The test is carried out on pipe sections with a specified diameter and a defined wall thickness.
The welded joints on pipe segments are tested in a 3-point bending test on shoulder specimens in accordance with DVS2203.
Hegewald & Peschke has the right testing system for all testing methods on pipes. Our portfolio also includes a 1D length measuring device for determining the overall length and individual measuring points along the pipe.
Three variants for the tensile test on pipes
Different types of specimens can be used in tensile tests to determine the mechanical properties of tubes, such as tensile strength or Yield strength. Which variant is used depends primarily on the tube diameter, wall thickness, material, and the available testing machines and grips.
In this option, the pipe as a whole is clamped into the tensile testing machine and subjected to axial loading.
Typical implementation
- Clamping area often with support cylinders inside the pipe (plugs) to prevent deformation during clamping
- Clamping with large pipe clamping tools
Advantages
- Testing of the actual component without changing its geometry
- Statement about the actual strength of the end product
Disadvantages
- Very large grips are required for pipes with large diameters
- High force requirements and correspondingly larger testing machines necessary
- Overall high costs for grip technology
Typical application
- Quality testing of finished pipes
- Validation of end products
In this option, the pipe is first flattened at the ends and then tested in a tensile test.
Typical implementation
- The pipe is mechanically deformed until a flat specimen is created at the ends.
- Grips are then used to carry out clamping, using standard grips for flat specimens.
Advantages
- No large grips required, even for large pipe diameters
- Cost-effective testing method
- Lower force required
Disadvantages
- Only suitable for ductile material
- Flattening can affect material properties
- Risk of breakage in the clamping area
- Only suitable for use with small wall thicknesses
Typical application
- Thin-walled metal pipes
- Rapid production checks
In this option, a standardized tensile test specimen is cut out of the pipe, usually in the shape of a dog bone.
Typical implementation
- Sampling from the pipe jacket
- Processing into a standardized tensile test specimen
- Testing according to standard tensile test standards
Advantages
- Significantly lower test force required
- Use of standardized test methods possible
- Cost-efficient testing
Disadvantages
- Greater effort required for sample preparation
- Material processing can alter local properties
Typical application
- Material characterization
- Comparison of different materials or batches
Apex pressure testing on pipes
Testing machines with different test room dimensions for various pipe diameters
- Compression testing machines of the inspekt se-ries for the determination of various material and component properties, including:
- Ring stiffness acc. to EN 9969
- Ring flexibility acc. to EN 1446, EN ISO 13968
- Minimum compressive strength acc. to EN 50086
- Crest compressive strength acc. to EN 1228
- Deformation behavior in creep tests acc. to EN ISO 9967
- Special extensometer for inside diameter testing with 2 measuring arms
- Length of measuring arms: 450 mm
- Accuracy 0.1 mm
- Sensor for measuring the inner pipe diameter
- The sensor is placed on the bottom of the upper pipe wall
- Enables precise measurement of the deformation of the pipe
- Cost-effective alternative to special long-distance and draw-wire extensometers
Nominal ring stiffness testing of glass fibre-reinforced plastic pipes
Component testing machine inspekt vario S-XL 600 kN & component testing machine inspekt vario SH 500 kN
- Testing of peak compressive strength according to DIN EN 1228
- Determination of compressive and circumferential strain
Component testing machine inspekt vario SH 500 kN
- 4-column testing machine
- test room
- Maximum specimen dimensions of the pipe strips:
- Width: 300 mm
- Diameter: 4000 mm
Component testing machine inspekt vario S-XL 600 kN
- 4-column testing machine
- Height 6 m
- Maximum specimen dimensions of the pipe strips:
- Width: 300 mm
- Wall thickness: 150 mm
- Diameter: 4200 mm
Nominal ring stiffness testing of plastic pipes
Universal testing machine inspekt S 50kN with a working area width of 750mm
- Determination of ring stiffness by measuring the force and deformation of the pipe at a constant deformation speed in accordance with DIN EN 9969
Universal testing machine inspekt S 50kN
- 50kN testing machine
- 4-column design
- Extended working space up to 750mm
- Special extensometer for inner diameter testing with 2 measuring arms
All test systems are equipped with the LabMaster testing software, which enables user-friendly setup and processing of the test procedures specified in the respective standards. It also offers great flexibility when integrating external devices such as the compression measuring device. Data import and export for customer-specific software such as QDAS or SAP is also possible.
Contact:
Hegewald & Peschke
Meß- und Prüftechnik GmbH
Am Gründchen 1
01683 Nossen
Phone: +49 35242 445-0
Fax: +49 35242 445-111
E-Mail: info@hegewald-peschke.de
Internet: www.hegewald-peschke.com
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