Pipe compression test for radial stiffness measurement
Pipe crown pressure test with a standard universal testing machine
Pipes are used for countless applications. If they have to withstand more than just internal pneumatic, hydraulic or mechanical pressure, it is necessary to test their resistance to external pressure. The pressure resistance must be tested for various applications and mechanical loads, e.g. when used as:
- Cable duct for electrical cables: pressure forces from people or fastenings
- in the ground: pressure within the underground installation
- as support rods for scaffolding or frames
- Climbing frames or stands for play equipment
- Constructions in trade fair construction, bridge construction
- … the applications are endless
Only a mechanical pressure test using a static universal testing machine can provide the designer or manufacturer with proof of the suitability of the product for its intended use. Therefore, a pressure test is applied to the outer diameter on a static universal testing machine. The pipe is placed on a hardened pressure plate and a compressive force is applied at its highest point (the apex).
In some cases, this test force is maintained for a defined period of time. At the end of the test, any inadmissible deformation is checked.
Modern universal testing machines perform these tests fully automatically. With GALDABINI material testing machines, the test can be configured so that the user (operator self-inspection) only needs to insert the tube and start the test. The method can be locked to prevent unauthorized changes to the test procedure and evaluation.
In the pipe crown pressure test shown, the universal testing machine and the testing software automatically:
test procedure
- the pipe diameter is determined (referenced pressure plate distance)
- a compression force of 1000 N is applied using a force ramp
- the compression force 1000 N is automatically held for 30 seconds
- the experiment ends after the holding phase has expired
- the current residual force is relieved of the preload
- the traverse (pressure plates) is returned to the starting position (insertion position)
The software automatically determines the following results:
Result |
Declaration |
Value |
| Pipe diameter | at the beginning of the experiment | mm Ø |
| maximum compression force | Control Overdrawing Force | N Newton (Fm) |
| compression path | at the end of the 30 S holding phase | mm compression set |
| compression ratio | based on initial diameter | % compression |
| minimum holding force phase | Control of holding force undershoot | N Newton (Fmin) |
