The Purpose of this operation is to prove the continuous diameter of the pipeline, i.e. the absence of any significant dents, ovalities or defects caused during the construction phase. This phase gives a baseline for the pipeline at the date of construction.

Gauging works usually carried out with 90% -97% of pipeline ID, 6-12 mm thickness Aluminium plate with redial incisions at 45⁰ intervals.

Restrictions beyond the tolerance established by the disk size will manifest themselves as damage to the gauge plate, so that any damage to the gauge plate is an indication that there is a dent or other unwanted feature in the pipeline that will need further investigation. The nature of the damage can allow SYGMA skilled engineer to assess the probable nature of the defect. Beyond this the decision may be taken to run a caliper pig or similar geometry tool capable of providing more detailed information regarding the position and nature of the restriction.