The Critical Nature of Coating Inspection in Corrosion Management

The Critical Nature of Coating Inspection in Corrosion Management

The Essential Role of the Coating Inspector

Effective corrosion management relies on coating inspection, carried out by a certified coating inspector. In this article, you’ll learn why coating inspection is critical, and the responsibilities of contractors and asset owners.

Quality of protective coating is not just desirable – it’s critical

As consumers, we are used to goods and services that we buy meeting a certain standard. In fact, quality is something we expect. After all, if the produce we buy from a supermarket isn’t up to scratch, we won’t shop there again. We expect a restaurant that comes recommended to produce the finest cuisine with exceptional service. If we’re disappointed, we make a complaint and refuse to pay the service charge.

However, in some situations we cannot afford to take a chance on quality. In industries such as oil and gas, rail, highways, and infrastructure, poorly executed work can be disastrous – not only financially but also with potential loss of life.

When a coating is applied to an asset, its primary purpose is to protect it against corrosion and give longevity of life to the asset; this process needs managing. The coatings need to be applied correctly by trained and certificated applicators, and certificated inspectors play a vital role in ensuring the process is delivered correctly.

A coating inspector’s work is to confirm that coatings have been applied correctly, to prevent corrosion that can have disastrous consequences.

Why can’t we just trust coating applicators?

In the UK, coating applicators are trained and qualified under the Industrial Coating Applicator Training Scheme (ICATS). Such training should ensure that applicators carry out their work in a professional manner and deliver a high quality of work. But it’s not quite that simple, and the risks associated with errors are too large to leave work unchecked.

People make mistakes, and a quality check makes sure that mistakes are corrected before they become expensive errors. A specification could be misread, or a detail missed.

In short, the coating inspector is a safety net, to help avoid dire consequences of human error.

Who is responsible for coating inspection?

The responsibility for coating inspection falls on both the contractor and the asset owner.

Contractors should have their own coating inspectors to check the work of their applicators. This is a mandatory requirement in industries such as rail and highways. It’s good business practice, and helps to foster good client relationships by ensuring quality of work is maintained.

However, the asset owner should never rely on the contractor to confirm the quality of their own work. That’s one huge conflict of interest to be avoided. So, good asset owners will employ their own coating inspectors, or hire a third-party coating inspector to check the protective coating application a second time. Using this strategy, asset owners should avoid the disasters that could be caused by contractors who may be tempted to cut corners.

In summary

Protective coating systems are complex. As we have been highlighting in our series outlining ISO 12944, coating is impacted by a range of factors that include:

Such factors make application complicated. It is therefore preferable for highly trained and suitably qualified professionals to collaborate. This should ensure that:

  • Specifications are met
  • Standards are maintained
  • Quality is assured

While the contractor will wish to ensure their work is of the highest quality, the ultimate responsibility rests on the asset owner. After all, it is in their best interests to make certain that disastrous failures of coating systems are avoided – a valuable by-product of which is that properly applied protective coatings will protect assets more effectively and reduce the costs of ongoing maintenance.

For more information about our Coatings Inspector Training, please email the Institute of Corrosion at admin@icorr.org.

61st Corrosion Science Symposium (Online)

61st Corrosion Science Symposium (Online)

The 61st Corrosion Science Symposium (CSS) will be held online during the week commencing Monday 14th September 2020.  The CSS Online is the annual meeting for students and researchers working in all areas of Corrosion Science and Engineering.  The CSS has been held annually since its launch in 1960 by Prof. L.L. Shreir. Holding a physical event was not going to be possible this year but we believe it is important to keep the CSS running even during these COVID times.  There will be no charge for the event.

To register for the event please visit the Eventbrite page:  61st Corrosion Science Symposium

Abstracts are still being accepted.  Please contact Julian Wharton (j.a.wharton@soton.ac.uk) if you wish to submit an abstract.

With the alternative online arrangements, we plan a programme of several sessions staggered through the week.  Each session will focus on a series of short (10 min) presentations with extended abstracts made available beforehand.  The sessions will be immediately followed by more in-depth online open forum discussion with the presenters.

A key highlight for every CSS is U.R. Evans plenary talk and presentation of the award.  The UR Evans Award is the most prestigious ICorr award and recognises outstanding contributions to corrosion science and engineering.  This year the award is being made to Prof Robert Cottis.  Prof Cottis has been a champion of corrosion education throughout his entire career with seminal contributions within UMIST/University of Manchester and activities linked to the European Federation of Corrosion (EFC) WP6 Corrosion Education and NACE International.

Download Presentation Programme

 

 

ISO 12944-4: Surface Preparation Standards

ISO 12944-4: Surface Preparation Standards

Preparing Steel Surfaces for Corrosion Protection Coating

In our previous article in this series discussing ISO 12944, the standard providing guidance for the corrosion protection of steel structures by protective paint systems, we looked at what the standard says about steel structure design and corrosion. In this article, we examine the main points of Part 4 of ISO 12944 which lays out instructions covering surface preparation for different types of surface.

What Is Surface Preparation?

Surface preparation is the first-stage treatment of a steel substrate which must be undertaken before applying a protective coating. Correct surface preparation is essential to the success of the corrosion protection coating being applied.

The objectives of surface preparation are to:

  • Remove deleterious matter
  • Produce a surface that enables paint to adhere to the steel
  • Minimise the contaminants that initiate corrosion

Mill scale must be removed from new hot rolled steel (in accordance with ISO 8501-1) in order to produce a surface profile that is appropriate for the coating system to be applied (which will be defined in the painting specification).

When surface preparation is carried out, health and safety regulations must be observed, and the surfaces that are to be prepared must be accessible and adequately illuminated. Burrs, sharp edges, and weld spatter should normally be removed around weld details and steel edges; this is generally carried out during the fabrication stage of new steel structures. More details on preparation grades can be found in ISO 8501-3, which define acceptance criteria based on a given specification requirement.

Factors that affect surface preparation

There are many factors that affect the surface preparation strategy and method chosen. These include:

  • Whether it is an existing or new structure (and age)
  • The structure’s location
  • The quality of the previous surface prior to preparation
  • The performance of the coating system
  • The type of corrosive environment
  • The coating system that is likely to be used

The preparation grade necessary to provide the required surface cleanliness and the surface profile (roughness) should also be considered.

Types of surfaces covered by ISO 12944-4

The standard covers surfaces of steel structures consisting of carbon or low-alloy steel of the following types:

  • Uncoated surfaces, consisting of bare steel (which are assessed in accordance with ISO 8501-1)
  • Metal coated surfaces, which include hot-dip-galvanised surfaces, zinc electroplated surfaces, sherardized surfaces, and thermally sprayed surfaces
  • Surfaces painted with prefabrication primer (in accordance with EN 10238)

The standard is mainly concerned with the protection of carbon steel new-build structures or extensive maintenance projects to be cleaned back to bare metal.

Surface preparation methods

The method used to prepare the surface for its corrosion protection coating should remove as much oil, grease, dirt, salts, and other contaminants as possible before further surface preparation is performed. Once known contaminants have been removed, testing may be required to detect less visible contaminants such as soluble salts (as per ISO 8502-6).

Any corroded material that exists should be removed by manual or mechanical techniques, though no sound metal should be removed unnecessarily. When preparing surfaces, the two types of surface preparation are:

  • Primary – which takes the whole surface to bare steel
  • Secondary – which leaves the sound parts of any coatings as they are

Methods that might be used to prepare surfaces for their protective coating include (but are not limited to):

·         Water, solvent, and chemical cleaning

A water jet may be used if the contaminants to be removed include water soluble materials and loose rust or paint coatings.

If detergents are used in the cleaning process, then the surface should be rinsed with clean, fresh water after cleaning.

·         Steam cleaning

Steam cleaning removes oil and grease, though again the surface should then be rinsed with clean, fresh water if detergent is added to the steam. Further testing may be carried out to determine the presence of oil and grease in accordance with ISO 8502-7.

Other methods to remove oil and grease include emulsion cleaning, alkaline cleaning, and organic solvent cleaning.

·         Chemical conversion cleaning

For hot-dip-galvanized surfaces, electroplated-zinc coatings, and sherardized surfaces, cleaning may be carried out by chemical conversion. Such treatments can only be used if the manufacturer of the paint system to be applied approves this type of cleaning.

·         Stripping

Solvent-borne pastes or alkaline pastes may be used to strip paint coatings, though this is usually used only on small areas and then followed by other appropriate cleaning.

·         Mechanical cleaning

Mechanical cleaning methods include cleaning with power tools, blast cleaning (of various types), and flame cleaning. Blast cleaning may be used to remove contaminants, to smooth or roughen the surface metallic coatings, or to remove a surface layer. ISO 8503-3 details these methods.

What if the surface preparation doesn’t achieve its aim?

The requirements of surface preparation are based on a range of preparation grades that are laid out in ISO 12944-4. If the required preparation grade is not achieved – or if the surface condition has changed before the coating system is applied – then further surface preparation must be carried out.

Who can carry out surface preparation work?

The standard is specific in describing who can carry out surface preparation work, saying that:

‘Personnel carrying out surface preparation work shall have suitable equipment and sufficient technical knowledge of the processes involved to enable them to carry out the work in accordance with the required specification.’

After the surface has been prepared, it must be assessed as fit for the coating system to be used. There are separate standards that regulate testing and how testing must be carried out – ISO 8501 and ISO 8502.

The Institute of Corrosion Coating and Inspection Training Courses – presented by IMechE Argyll Ruane and Corrodere – will help ensure your painters and inspectors work to the latest industry standards and benefit from new technology and innovative approaches. For more information, contact us today.

In our next ISO 12944 article, we look at laboratory performance test methods and the changes that were made to these in the latest revision of the standard.

In the meantime, if you have any questions, please feel free to get in touch with ICorr or download our guide ‘Surface Preparation Methods’.

Survey Drones can now go beyond line of sight

Survey Drones can now go beyond line of sight

The use of drones for aerial inspection and survey is increasing, and their usefulness is set to increase with a demonstration by AmeyVTOL of a drone inspection carried out beyond the visual line of sight.

AmeyVTOL is a joint venture between Amey and aerial robotics specialist VTOL Technologies. AmeyVTOL’s drone, known as The Flying Wing, has a flight range of up to 100 km, and sensors that enable it to capture and send data in real time.

During the demonstration, The Flying Wing autonomously surveyed an area out of the sight of the pilot up to 2km away.

According to Amey, the success of the trial opens up the use of drones for inspections of long linear infrastructure such as roads, railways and overhead power lines, saving time and cost, and improving the safety of staff.  The demonstration project was part of a government-sponsored Rail First of a Kind (FOAK) programme promoted by Innovate UK through the Small Business Research Initiative.

It is reported that AmeyVTOL will now be offering this survey capability to other infrastructure owners and operators.

Corrosion to Covid-19: one start-up company’s effort to support UK front line workers

Corrosion to Covid-19: one start-up company’s effort to support UK front line workers

Hexigone Inhibitors, a Sustaining Member Company, who usually manufacture chromate-free corrosion inhibitors, are now using their large mixing vessels to produce hand sanitiser to help protect staff on the front line. The sanitiser, which meets the standard set by the World Health Organisation, is already in use in local organisations.

The UK Government’s innovation agency, Innovate UK, linked-up Hexigone with pharmaceutical giant, Glaxosmithkline, who subsequently donated 8,000 litres of isopropanol to ramp-up production.

For the sanitiser to be effective, it must contain at least 60% alcohol. The batches made by Hexigone are 75% – precisely made to the WHO recommended formulation – ensuring that the coronavirus and other microbial pathogens are killed. Other ingredients include water to dilute, glycerol to moisturise, hydrogen peroxide to kill any fungal spores, and finally, lemongrass essential oil to scent
the sanitiser.