SmartSensors are reliable and monitor the rig structure 24/7. (Images courtesy of Thermal Technology Services Inc.)

How much downtime could be saved if an entire rig were monitored 24/7 and an alert issued at the exact location on the rig any time a joint had fractured or the rigs’ metal was so corrosive that it no longer functioned?

Harmonic footprinting

Complete metal fatigue — or even wear before complete failure — can be continuously measured. Using “vibrational” technology, metals have a molecular structure that when excited creates a dominant resonant frequency, a number of minor resonant frequencies, and amplitude that can be graphically observed.
A vibrational metal fatigue evaluation can be conducted to determine metal structural and molecular degradation by observing and recording its resonant frequencies and amplitudes. The evaluation identifies the metal’s remaining life expectancy without destructive laboratory testing or the need to remove the metal part in question from service.

Using the “footprint”

SmartSensors are placed on metal joints throughout the rig. Each joint is then struck by a controlled force, and the resulting amplitude is transmitted by the SmartSensor to be cataloged in the resident software database. This provides a unique “footprint” for each metal joint. Once the footprints are catalogued, the joints are monitored 24/7, with new footprints constantly being captured and sent. Should the new footprint fail to match the cataloged footprint (within an acceptable range), an alert is issued by the software that displays the exact location of the metal in question.

How can harmonic footprinting assist rig operations? SmartSensors can be positioned throughout the rig at each critical joint location, continuously transmitting metal footprints for evaluation. Readings can be available before, during, and immediately after a large storm or hurricane. Instead of waiting until the storm passes to manually inspect the entire rig before placing it back online, rig operators would know exactly what, if anything, needed to be inspected and replaced, even before the storm was over.

Harmonic footprinting science

Metals have a molecular structure that when excited demonstrates (presents) a dominant resonant frequency, a number of minor resonant frequencies, and an amplitude.
These frequencies and amplitudes are dependent on and created by a number of factors such as the forming process, heat treatment and quench, machining, elemental exposure, and other outside factors.

When an outside stimulus, such as a collision (a weather factor, traffic, heavy load, etc.) is applied to metal, the internal (molecular) structure resonants for some period of time. The degree of time of this amplitude is directly dependent on the degree of the stimulus, the power of the impact or collision. In addition, the degree of amplitude is directly proportional to the mass of the part length dimensional inconsistencies, and quality of origination.

This resonant frequency, harmonic response is similar to metals having the same mass and dimension characteristics, assuming these components are produced under the same conditions.

With these consistencies as constants, the vibrational fatigue evaluation process (harmonic footprints) can be used to determine structural degradation and molecular degradation to any metal having resonant frequencies and amplitudes, thereby determining the remaining service life of the metal component without destructive laboratory testing, or removing the part in question from service.

The methods can also be used to determine factors in new parts that will affect the performance or usable life of the part or cause the part to improperly interact with mating components. These factors are compressive stresses, inclusions, fractures, voids, and other factors caused by poor forming, heat treat, or sintering.

The method used to determine the resonate frequency/amplitude of components in the vibrational fatigue evaluation process is based upon baseline resonant frequencies and amplitudes determined prior to installation or at the time of installation with software developed by harmonic footprinting. The software constantly receives impressions from the sensors. Should the footprint fail to match the footprint previously recorded, the inspector is immediately alerted to the exact location of the metal fatigue.