Magnetic Flux Leakage (MFL) is a method of non-destructive testing that is used to detect corrosion and pitting in metallic pipelines. MFL tools scan the full circumference and length of a pipeline, providing high-resolution information on pipe wall condition. MFL scans the pipe through linings to measure remaining wall thickness and provide depth and location…
ABSTRACT There is a constantly growing need for products and technologies that for their realisation require hermetically closed elements, vessels and tubes. Envelopes with greater or smaller vacuum tightness had to assure a satisfactory isolation between external atmosphere and inside over- or underpressure. Crytical leak spots in closed systems are usually: connections, gaskets, welded and brazed joints, defects…
What is a Leak? A leak is a flow of gas (or liquid) through the wall of a vessel (via an imperfection such as a hole, crack or bad seal). Leaks require a pressure difference to generate the flow; they always go from higher pressure to lower pressure. Leaks are pictured as going from positive pressure…
Laser Testing includes three techniques, Holography, Shearography and Profilometry. As the method name implies, all three techniques user lasers to perform the inspections. LM TECHNIQUES Holographic Testing Holographic Testing uses a laser to detect changes to the surface of a part as it deforms under induced stress which can be applied as mechanical stress, heat, pressure, or vibrational…
What is Ground Penetrating Radar? Ground penetrating radar (GPR) is a non-destructive geophysical method that produces a continuous cross-sectional profile or record of subsurface features, without drilling, probing, or digging. The GPR cross-section shows the ground surface at the top of the profile, and the reflections of subsurface geologic units and objects to a certain…
Guided wave ultrasonic testing detects corrosion damage and other defects over long 33 ft. – 165 ft. distances in piping. A special tool (transducer ring) is clamped around the pipe and transmits guided waves in both directions along the pipe. Reflected signals from defects and pipe features such as welds are received by the transducer…
Eddy current testing for external defects in tubes where external access is not possible (e.g. buried pipelines), is conducted using internal probes. When testing thick-walled ferromagnetic metal pipes with conventional internal probes, very low frequencies (e.g. 30 Hz for a steel pipe 10 mm thick) are necessary to achieve the through-penetration of the eddy currents….
Conventional eddy current inspection techniques use sinusoidal alternating electrical current of a particular frequency to excite the probe. The pulsed eddy current technique uses a step function voltage to excite the probe. The advantage of using a step function voltage is that it contains a continuum of frequencies. As a result, the electromagnetic response to…
Swept frequency eddy current techniques involve collecting eddy current data at a wide range of frequencies. This usually involves the use of a specialized piece of equipment such as an impedance analyzer, which can be configured to automatically make measurements over a range of frequencies. The swept-frequency technique can be implemented with commercial equipment but it…
Multiple frequency eddy current techniques simply involve collecting data at several different frequencies and then comparing the data or mixing the data in some way. Why the need for multiple frequencies? – Some background information The impedance of an eddy current probe may be affected by the following factors: ● variations in operating frequency ● variations in electrical…