7/25/2019 Plant Integrity Case Study CUI Jetty
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Plant Integrity LtdGranta Park, Gt Abington, Cambridge CB21
6GP
T:+44 (0) 1223 893994 F:+44 (0) 1223 893944
[email protected]
www.plantintegrity.com
TechnicalBrief
A TWI Group Company
Corrosion Under Insulation(CUI)
The Teletest Focus+ system is a Guided Wave NDTTechnique
developed for screening pipe-work forareas of metal loss
damage.
It is a pulse-echo system aimed to inspect largevolumes of
material from a single test point. The initialapplication was for
the detection of corrosion underinsulation for petrochemical plant
industry, but it hasevolved to be used widespread in other
inspectionsituations where pipes or tubes are not
accessible.Examples of this are lines that are buried, encased ina
sleeve or elevated above the ground.
Plant Integrity Ltd was requested by one of its clientsin
Argentina to employ the Teletest Focus+ systemon two cryogenic
jetty lines at 8 and 3 diameters.The inspection proved to be very
successful with100% of both lines being inspected over a 2
weekperiod.
Figure 1 Location of anomaly area highlighted in fig 3
Each jetty line was approximately 2km in lengthincluding several
expansion loops and pipe bridges.Several anomalies were identified
during theinspection and follow up was conducted whilst
theoperators were still on-site. The first anomalyidentified was
located during the opening shot of theinspection; this was of
upmost interest to the client asthe location was in a difficult to
access area seen infigure 1.An anomaly classified as medium
priority wasidentified approximately -3m from the tool position(see
figure 3).
Figure 2 corrosion detected at 180
The area of interest was directly above water so anaccess
platform had to be erected to allow follow upto take place at this
location. Upon removal of theinsulation the inspection team
identified externalcorrosion at the 180 position seen in figure 2.
Thisarea of corrosion was approximately 1 meter in lengthand 35%
wall loss.
Figure 3 TL01~location of detected anomaly
The A-map scan (see figure 3)was also used in the
identification of this anomaly. The signal from theweld
identified at approximately -13m from the toolposition does not
display an axi-symmetric response.This echo response from the weld
signal should bedisplayed as an even distribution of
colourrepresenting uniform circumferential signal amplitude.The
above gave the operator increased confidencethat the signal seen at
-3m was in fact attributed to awall loss defect.
For information on how we can support your pipelineintegrity
management programme, please contact us byemail at
[email protected] or by telephone at ourCambridge, UK
headquarters on 0044 1223 893994.
1 meter
Anomaly
Weld
