ISO 18211:2016

ISO 18211:2016 specifies a method for long-range testing of carbon and low-alloy steel above-ground pipelines and plant piping using guided ultrasonic waves with axial propagation applied on the entire circumferential pipe section, in order to detect corrosion or erosion damage.
The guided wave testing (GWT) method allows for fast inspection of above-ground pipelines, plant piping and cased road crossings, giving a qualitative screening and localization of probable corroded and eroded areas. GWT is typically performed on operating piping systems.
ISO 18211:2016 is applicable to the following types of pipes:
a) above-ground painted pipelines;
b) above-ground insulated pipelines;
c) painted plant piping;
d) insulated plant piping.
NOTE Pipe sections within road crossings with external casings (without bitumen or plastic coating) are a special case of buried pipe where there is no soil pressure on the OD of the pipe. ISO 18211 :2016 applies to these cased road crossings.
Other types of pipes not included in the above list need dedicated approaches due to increased complexity.