Does my MRU need recalibration?
The Norwegian Subsea MRU calibration certificate is valid for 4 years, and full product specification is maintained in this period under normal operating conditions.
Notes:
- We do not normally advise re-calibration of the MRU during its lifetime.
- The specified heave accuracy of 5 cm / 5% is maintained over the MRU's lifetime, also without re-calibration.
- The specified accuracy in roll & pitch for a given model is usually met over the MRU's lifetime under normal operating conditions as Norwegian Subsea uses only validated sensors with exceptional stability.
- Re-calibration and validation of the MRU every 4th year is recommended only if the customer requires full product specification after expiration of a valid calibration certificate.
- The lifetime accuracy in roll & pitch, without re-calibration and under normal operating conditions, not exceed
- 0.1 degrees for the 3000 model
- 0.05 degrees for the 6000 model
- 0.02 degrees for the 9000 model
- Thus, selecting a more accurate model than initially required may extend the calibration intervals or remove the need for re-calibration.
- The computed MTBF (mean time between failure) for a NORSUB MRU Marine is 100 000 hours, but actual lifetime depends on use, vibrations, and temperature. An MRU lifetime of 10 years or more under normal continuous operation can be expected.
In summary, for most applications, no recalibration is required. Examples:
- The MRU 3000 for Helideck monitoring applications. The requirement is 0.1 degrees roll/pitch accuracy and the MRU 3000 will always stay within this accuracy requirement without recalibration.
- The MRU 3000 Marine for DP systems roll/pitch sensor. The MRU 3000 will always stay within the accuracy requirement without recalibration.
Re-calibration and validation of the MRU is done in the factory in Oslo, Norway. Normal turn-around time is one week. Re-calibration includes a complete validation of the MRU, ensuring that the MRU is in full working order.
