Perimeter variation measuring system
Pipes for oil and gas flow are constantly subjected to various tests for performance evaluation. Among the most common loads are internal and external pressurization, as well as axial and radial loads. These imposed conditions alter the geometric forms of the pipe, among them the external perimeter.
Símeros has developed a simple and practical device that measures the variation of perimeter of the pipe’s cross section, from which diameter variations in circular sections can be inferred. The measuring device was initially designed to be used in full-scale flexible pipe tests, and has subsequently been upgraded for direct operation applications.
The development process has begun via the evaluation of several concepts. The engineering team determined the model that best fits the imposed restrictions, taking into account the manufacturing of the first prototype. To determine the uncertainty of the device’s measurement a verification system has been created which can impose perimeter variations, which can be measured using properly calibrated instruments.
One of the verifications studied was the behavior of the measurement system against temperature gradients normally encountered in operation, since the metallic components that constitute the system have inherent influence of the temperature, which interferes directly in the measurement uncertainty. In order to consider this effect, a battery of laboratorial tests were carried out that resulted in the selection of geometry and materials with optimal thermal performance. Thus, a correction coefficient was also established, which compensates for the effect of the temperature variation present in environments where this variable cannot be controlled.
The other variables that considerably influence the measurement were identified and minimized, giving way to a new version of the equipment with several upgrades: more robustness for field assembly and smaller sensibility to misalignments, resulting in a reduction of measuring uncertainty.
To obtain the perimeter or diameter variation of the pipe during test execution or during operation, a data processing tool was developed which interacts with the measuring and data acquisition equipment, plotting the evolution of the variables. The system operates autonomously and without the need for operator intervention.
Hyperbaric perimeter variation measuring system
The expertise gained in the development of the perimeter variation measurement system has allowed the evolution to a concept that performs the measurement in an environment of high external pressure, such as tests inside hyperbaric chamber or measurements in pipelines installed in deep or ultra-deep waters.