Ultrasonic Corrosion Mapping
Ultrasonic corrosion mapping is the preferred method for critical vessels generally in petrochemical. Ultrasonic mapping provides the owner with a detailed C-Scan image of the inspection surface via the means of a semi- automated scanning system.
Silverwing’s RMS2 450 is high-speed remote access ultrasonic corrosion mapping system designed for the circumferential scanning on diameter of more than 152mm (6 inches).
Ultrasonic data is recorded from a single crystal immersion transducer and displayed within the software as a coloured coded C-Scan map, with differing thicknesses represented as changes in colour.
Each thickness level is colour coded and wall thinning by corrosion or erosion is more readily recognised than by manual inspection.
To accompany the RMS2 450 is the Thetascan system which is designed for corrosion mapping of areas inaccessible to the RMS2 such as saddles and dome ends.
The ThetaScan is a dry coupled, manual ultrasonic C-scan imaging system which is can be operated both on flat plates and curved surfaces with a diameter larger than 300mm.
The Thetascan system continuously records thickness measurements as the scanning head is moved over the inspection surface. During a scan, thickness information is presented as an A-scan trace, a digital thickness measurement and a C-Scan image.
Ultrasonic Thickness Measurement Inspection
Ultrasonic thickness measurement inspection is performed to determine the internal condition and remaining thickness of a vessel. Thickness measurements may be obtained when the vessel is in or out of operation and should be performed by a qualified inspector. Silverwing supply two types of ultrasonic thickness gauges, the T-Scan 100 and the range of T-Scan 300. The T-Scan 100 is designed for non-coated inspection surfaces whereas the T-Scan 300 range is designed for coated surfaces.
With the advances in technology and reporting capabilities more and more engineers recommends equipment such as the dry coupled R-Scan Lite which continuously records thickness measurements as the scanning head is moved over the inspection surface. Inspection results can be viewed in real time in the field or recalled for post inspection analysis at a later date.
Magnetic Flux Leakage Screening
Magnetic flux leakage (MFL) is a corrosion screening technique which is not affected by product
within the vessel so surveys can be carried out in-service or out of service. MFL is a quick and easy method for detecting corrosion which should then be backed up by ultrasonic for suspect areas. Silverwing’s PipeScan is a cost effective MFL inspection tool which is design to operate on
curved surface with an outside diameter of 48 mm to 2400 mm. Larger vessels and tank shells may also be screened using the Silverwing HandScan system
MFL screening relies on the detection of the magnetic flux, which is 'squeezed' out of the pipe under test by any decrease in the wall thickness.
In order to achieve this, the pipe wall needs to be close to magnetic saturation. The amplitude of the signal obtained from any wall loss is proportional to the volume that is missing from the region interrogated.
External Visual Inspection
The inspection shall, at the least determine the condition of the exterior insulation, the condition of the supports, the allowance for expansion, and the general alignment of the vessel on its supports. Any signs of leakage should be investigated so that the sources can be established. Inspection for corrosion under insulation shall be considered for externally-insulated vessels subject to moisture ingress.