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March

2017

HYDROCARBON

ENGINEERING

68

outdoor equipment, even very small gaps in

insulating cladding can allow in enough water to

cause significant corrosion issues.

Another challenge created by insulation is that it

can hide the effects of the corrosion from view, so

that a heavily corroded pipe can appear normal

when visually inspected. By the time the effects are

visible from the outside – often in the form of

particles of oxidised metal or discoloured water

running off – significant damage has already been

done.

Removing insulation to check the condition of

pipework is a laborious process and a costly method

of assessing the condition of an asset. This makes it

one of the first areas to receive less attention when

budgets get tight, but it is a cut that companies

cannot afford to make. With this in mind, specialists

in the offshore sector have developed a number of

different solutions that can make managing CUI

across an installation more efficient and help ensure

pipes and structures conform to health, safety and

environment (HSE) guidelines.

End-to-end efficiency

The biggest cost associated with corrosion

inspection is manpower. When offshore facilities are

involved, that includes the process of getting the

right personnel on board and ensuring that they

receive the correct briefing, which can be a time

consuming process. However, this argument is also

true for downstream facilities, where giving the right

personnel access to the site can involve long

distance travel, accommodation costs and

certification issues.

The focus is therefore on minimising resources

needed to carry out the work. At Bilfinger, this is

tackled by having inspection and fabric maintenance

departments work together, using three man

multi-skilled teams that include an inspector,

insulator and painter, all of whom are rope access

qualified. Keeping the teams as small as possible can

lead to considerable cost reductions. It is better still

if one can avoid transporting new personnel to site

to carry out an inspection altogether, by training

team members that are already on location to carry

out the inspection work.

Getting smart with detection

technology

There have also been significant technological

advancements in recent years that have increased

the efficiency and effectiveness of inspection crews.

Ensuring teams are equipped with the latest

advanced CUI detection tools, such as digital

radiography and pulsed eddy current (PEC)

technology, is another vital aspect of speeding up

site inspection processes and improving the

likelihood of early detection. There is now a lot

more that can be done to detect hidden corrosion

than simply carrying out visual detection. Using

advanced imaging techniques, which make use of

non-visible electromagnetic effects to detect the

condition of pipework, can indicate issues earlier

and more reliably.

While both radiographic and PEC imaging have

been known about for a long time, the technology

used to carry out inspections has advanced rapidly

in recent years. Where once each radiographic

exposure took several minutes to capture and

subsequently needed to be processed using

laboratory equipment, these can now be carried out

in a matter of seconds, providing images to view

instantly on a mobile device.

Similarly, while PEC readings as recently as

five years ago needed to be carried out on a

point-to-point basis, making it time consuming to

capture all of the angles and positions required to

scan a length of pipework, the latest systems

developed by Eddyfi run continuously. This reduces

the time taken and significantly increases the

number of data points available, providing greater

certainty of results. Implementing these advanced

detection techniques will always involve a large

element of data analysis and interpretation. Finding

an efficient way of carrying this out is essential in

delivering an efficient end-to-end service.

The power of portable technology today means

that this process can now often be carried out on

the ground, rather than needing to save or relay data

for desktop analysis later. Portable digital solutions

put a wide range of functionality at the inspection

engineer’s fingertips by incorporating a large

touchscreen and extensive battery life to allow

performance through a shift. Combining the required

features with a robust design often means the units

can be larger than a handheld unit, so a well

designed harness to allow comfortable extended use

is also critical.

The software embedded in this technology can

facilitate the whole process, from setting up a new

inspection regime to conducting the examination

and generating detailed reports. Now that engineers

are able to output easy to interpret condition

reports, clearly showing the location and extent of

any defects without any subsequent need to analyse

the data, the ability to respond rapidly to other

urgent situations is increased. For many inspections,

dependence on rope access can also be reduced by

using un-manned aerial vehicles (UAVs) – or drones.

Once the presence of CUI has been identified, an

efficient strategy for replacing affected insulation is

essential.

Case study

Bilfinger was called in by a contractor operating a

platform for a major global energy company to

renew the insulation on all exterior pipework where

CUI was detected. The existing insulation on the

pipework was mineral wool, enclosed in neoprene

cladding, and the cause of the CUI in every case was