Dynamic Fatigue Test

One of the most important parameters of the design of a flexible pipe is the projection of the work life, as well as its safety factor. Since the extracted hydrocarbons have a high aggregated value, a catastrophic failure caused by use outside of the acceptable safety margins, could lead to an environmental disaster of large proportions. It is of great importance, therefore, the verification of the design methodologies adopted through full-scale dynamic tests. Such tests aim to simulate predicted operational conditions throughout the whole service life of the flexible pipe in operation.

One of the critical sections of the oil exploration flexible pipes is the top side riser, because it is in this region where the interface with the production rig is located, being under the greatest bending and traction loads. Therefore, this region becomes critical for the determination of the expected service life. Aware of this, Símeros has at its disposal a test bench capable of executing dynamic tests that combine traction with bending loads with capacity to apply dynamic axial load of 500 tonne (5,000 kN) and apply simultaneously a bending moment of 875 kNm at angles of up to 20°. Currently the bench allows samples of up to 16 m to be tested and that accessories, such as bend stiffeners, are coupled with the sample. In addition, in order to get closer and closer to the conditions met in the field, Símeros developed an annulus flooding system to use during testing so that it is possible to monitor variables such as pH, dissolved oxygen, pressure and temperature of the fluid passing through the annulus of the flexible pipe. We also have an equipment that can apply up to 19,000 psi (1,310 bar) of internal pressure in the samples.

 

 

The main fatigue failure mechanism on flexible pipes occur through the rupture of the tensile armour wires, since it is this layer that has to withstand the largest portion of the applied loads. Therefore, it is extremely important to use a robust and safe monitoring system that is capable of pointing out the occurrence of such events with a great degree of reliability during the test. To do this, Símeros has an own system of event detection, which uses several sensors, such as inclinometers and accelerometers. During the course of the test, the data is processed and sent to the client via our own data processing system in the cloud, which enables multiple levels of backup while maintaining the integrity of the test data.