Monitor Your Highly Corrosive Scrubber Systems With Ultrasonic Technology

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  • Through-life maintenance support
  • We still maintain units built 20 years ago
  • Extend trade-in credits - replace old units for new
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  • Be a life-safety technology partner – Permalevel™
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Coltraco manufacture Ultrasonics That Work

Monitor Your Highly Corrosive Scrubber Systems With Ultrasonic Technology

The International Maritime Organization (IMO) regulated that ships must cut their sulphur oxide emissions by 2020. As a result of this, shipping companies have turned to scrubber systems, which reduce the amount of sulphur emitted from burning fuels. Scrubber systems allow a ship to continue using cheaper bunker fuel than low sulphur fuel which reduces the switching cost to an entirely new fuel system. The sulphur in exhaust gas is neutralised in the scrubber tower by the absorbent used such as sea water and passed out from the discharge pipe.

Unfortunately, scrubber systems come with their own issues. The piping in the scrubber system is very prone to corrosion, particularly in the discharge valve. This is due to the elevated temperatures of the exhaust gas scrubber discharge which creates a very corrosive environment. The risk is that a reduction in wall thickness would mean that corrosion is present.

Therefore, DNV GL has introduced a requirement whereby piping in scrubber systems should be annually checked for their thickness.

As stated in 2017 by DNV GL: “Newer SOx scrubber systems often are equipped with diffusers inside the distance piece. These diffusers themselves are vulnerable to corrosion attacks, but more important, their fixation to the distance piece, either welded or bolted, often forms a weak spot in the corrosion protection of the distance piece. For the safety of the crew and the vessel, we believe it is necessary that the condition of the distance piece be confirmed on a yearly basis.”

DNV, GL - Survey requirements for fleet in service Part 7, Chapter 1, Section 2, 3.1.9:“The wall thickness of distance piece(s) for SOx scrubber system discharge valve(s) shall be verified to be undiminished.”

The recommended solution is UTM (ultrasonic thickness measurement). Ultrasonics is the simple and effective solution for testing for corrosion, required by DNV GL. Coltraco Ultrasonics are proud industry experts in ultrasonic technology. Coltraco manufacture two industry leading ultrasonic thickness gauges, ideal for the regular testing of scrubber systems.

Portagauge® 3 is a low cost single-echo portable thickness gauge. The quick, simple and hardy Portagauge® 3 allows accuracy of ±0.1mm even on corroded, challenging and some plastic surfaces. With a 50 hour battery life, measuring thickness ranges between 1.5mm to 99.9mm and a variety of verified testing materials such as steel, quartz and glass PVC, the Portagauge® 3 provides the versatility  to suit a range of safety needs. This easy to use ,highly dependable handheld unit is ideal for scrubber systems.

For more advanced requirements - identifying the metal only thickness - Coltraco Ultrasonics also have the Portagauge® 4 which is an advanced thickness gauge. Offering unparalleled accuracy, the Portagauge® 4 uses triple echo technology which allows operators to inspect the underlying metal thickness, independent of any surface coatings such as paint. For applications where true metal readings and a higher degree of accuracy is required, the Portagauge® 4 is the ideal solution. With a variety of sensor options available and underwater variants, this range of units can easily be adapted to a variety of different roles and requirements.

Discover more about Coltraco Ultrasonics’ commitment to customer care and safety on


CEO Message

Integrity and Science Key to Our Culture of Performance

Dear Coltraco Customers, Strategic Partners and Distributors,

Integrity is our defining value. Performance is its consequence. We understand that our customers have choices, and how we perform determines whether customers choose us. Coltraco’s Code of Ethics does not merely require compliance with laws. It embodies a Commitment to positive behaviours that build trust, promote respect, operate with distinction, with courtesy and global levels of performance, demonstrating our integrity and delivering customer performance.

We honour our commitments, communicate transparently, and act with honour. Ethics are the foundation of our performance culture and our science-based approach. We lead in specific technologies delivering the watertight integrity monitoring of marine structures and the monitoring of fixed liquefied gaseous fire extinguishing systems and the room integrity of protected space to ensure agent hold-times post-installation. We show this by our understanding of the science in them and the mathematics that explain them.

I would like to thank you for your business and for the relationships with our Customers, Strategic Partners, Distributors and ODAs who we value so highly.

My kindest regards,

Carl Stephen Patrick Hunter BA(Dunelm) Hon DSc FRINA FIMarEST MRAeS
CEO & Managing Director
Coltraco Ultrasonics Limited
46-47 Mount Street, Mayfair, London W1K 2SA
United Kingdom

Tel:  +44 20 7629 8475
Fax: +44 20 7629 8477

Call Now : +44 207 629 8475


References in PDF Format


Underwriters LaboratoriesUnderwriters Laboratories


Reference Alpha Fire UK Portalevel MAX Sept 2012

Reference Portascanner-II CSD MOD Albion and Bulwark





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