Guided wave inspection is performed on fixed inspection intervals prescribed by governmental regulations that are sometimes not in line with the maintenance requirements. Since guided wave is a surveying tool, the guided monitoring is required to do in-service testing before a planned shutdown. Ample time is then available to plan the necessary maintenance work long before the actual shutdown takes place. Therefore, total downtime for the installation is reduced.


The MsS System has a number of advantages  compared to other systems like those based on piezoelectric collars in guided wave monitoring. Since the MsS system is based on the magnetostrictive sensor (MsS), the benefits of long-range guided wave monitoring with MsS system are:


- MsS probes are much cheaper than piezoelectric ring probes.

- The probe is light (less than 0.5 kg for 24-inch-OD pipe), so that the installation work is easy at high level.

- Easy to install in structures for monitoring

- No limitation of pipe size exists because the MsS probes are directly made on site   with material.

- Only a 25-mm clearance is needed around the pipe in permanent monitoring.

- MsS probes work well at high temperature pipe up to 300°C.



In MsS guided wave monitoring, the MsS probe is permanently installed at a corrosion-sensitive region of structure; baseline data are obtained; the structure is periodically tested; and the periodic data are compared with the baseline data to identify structural changes with time.



The merits of MsS guided wave monitoring compared to inspection are:

- Quickly obtain new data with the installed probes

- Data is acquired from the same location of probes

- Small changes in condition can be readily detected with comparison of baseline data and periodically monitored data

- Finds defect initiation and growth in geometric features such as weld, support, attachment, etc.

- No need to remove insulation or excavate soil for the probe installation except the first  time

- Allows in-service testing in high temperature or high elevation line.

- Gives ample time for maintenance works and reduces total downtime.