Learnings

Outcomes

The summary of the work is presented here in 3 core project activities:

Superior Corrosion Coatings (for new and old pipes)

The formulation developed under this category and the testing carried out are the closest to the commercial deployment. There are few aspects that require testing and development, namely the field trials, coating scale-up and development of protocols for large-scale deployment onto the assets. The paint has shown the following interesting features:

·       Corrosion protection of a commercially used paint is enhanced by graphene additions, this could enable deployment in assets that require a higher level of protection.

·       Thinner coating can be used with graphene with the same performance level, which can result in financial savings, due to reduced paint consumption (estimated at £223 per km for paint systems considered).

·       Less paint, less maintenance and less wastage also has associated environmental and procurement benefits.

The results from the corrosion resistance can be summarised as follows:

·       Graphene loadings above 0.1 wt% with poor dispersion in the red oxide can enhance corrosion, but a loading of well-dispersed 0.01 wt% performs significantly better than the reference red oxide.

·       The deposition of the paint coating in 2 layers generates a more stable coating less prone to defects that could compromise its anticorrosion performance.

·       The deposition method influences the corrosion performance of the coating, it is therefore a critical parameter to consider for the future deployment of the paint system.

·       Well dispersed Levidian graphene enhanced red oxide paint has superior corrosion performance than the reference red oxide, especially for lower concentrations of graphene between 0.043 wt% and 0.43 wt%.

·       The addition of the conductive graphene layer, required for smart sensing in the sandwich configuration, does not affect the corrosion performance of the system but rather further improves the stability of this coating technology.

Smart Sensing for health monitoring (for new and old pipes)

In this area of the project, a special formulation was created using a primer and graphene multilayer coating, which is capable of giving different electrical signals under different external stimuli. The results so far indicate that current and voltage, required to power this coating, is within the power range already available on the pipeline assets for the cathodic protection used on pipelines. This coating could monitor torsional deflection forces and be used in complex environments or areas when human monitoring is challenging. This coating could reduce the number of required site inspections but most importantly provide information about the pipeline health in advance of any visible damaged to the asset.

The results from the smart sensing can be summarised as follows:

·       A specially developed graphene paint for smart sensing can be used to monitor the pipelines without deploying a large number of sensors and staff to the field.

·       A graphene layer can be used to detect external factors affecting the coating, such as humidity, pressure, deformation or damage.

·       The use of red oxide with a high graphene loading of 30 wt% instead of pure graphene for the conductive layer not only facilitates the deposition of the material since the red oxide acts a binder, but also gives a better performance of the coating with a faster response and less noise.

Hydrogen embrittlement protection (for new and old pipes)

This part of the project requires most development, particularly that the effect of hydrogen on the pipe has to be determined using real testing nevertheless the effect of the coating on the overall contribution to the hydrogen permeation was demonstrated. The important step is now to follow up on the mechanical testing protocol developed towards the end of this project. The mechanical assessment is critical for the demonstration of the hydrogen effect on the pipe material and also test the actual impact on the hydrogen permeation into steel. 

An unexpected finding was made involving the coefficient of friction, specifically the reduction of the friction coefficient and potential reduction of the energy needed for the movement of gas through the pipeline network.

The results from the hydrogen permeation programme can be summarised as follows:

·       The barrier coating properties of the red oxide primer paint system (which is being utilised as internal coating for the natural gas pipelines) and graphene enhanced paint system at various concentrations was investigated.

·       Rheology and corrosion testing highlighted that the quality of dispersion of graphene within the polymer primer was critical to the coating performance. To this end, a master batch dispersion with advanced mixing techniques from Levidian was trialled with positive results.

·       The Levidian prepared graphene dispersion showed that addition of graphene to red oxide primer decreased the hydrogen permeation through the coating by 177%. The permeation value dropped from 61668 to 3714 ml/m2·day·atm when values between pure red oxide and 0.01 wt% graphene enhanced red oxide was compared.

The project value tracking is listed below:  

·         Maturity

o  TRL 1-3 – Fundamental research on the opportunities to use functional graphene to improve performance of gas transmission assets.

·         Innovation Opportunity

o  50% or multiple asset classes – Project investigated coatings for three applications: 1. External corrosion protection of painted assets. 2. Smart sensing coatings for corrosion management of painted assets. 3.  Internal barrier coatings to mitigate hydrogen embrittlement of gas-facing steel assets (focus on pipe).

·         Deployment Costs

o  £0.00 – No direct deployment costs as this is a research project. However, with regards external paint systems, costs would be incurred to deploy new paint systems to assets - although the aim would be for the new paint systems deployment costs to be similar to existing external paint systems. With regards smart paint systems for corrosion or damage detection/monitoring, there would be costs associated with deployment, but these would be offset by the benefits of such a system. With regards internal barrier coatings, there would be significant deployment costs associated with in0situ deposition, however, these would be offset by the benefits of such a system.

·       Innovation Cost

o  £ 615,000.00 – Cost of innovation project. Further innovation costs would need to be incurred to develop technologies further prior to deployment.

·         Financial Saving

o  £ 222.63 – No direct financial savings as this is a research project. However, improvement in corrosion performance of external paint systems could result in financial savings due to reduced maintenance costs. Furthermore, savings of £222.63 per km of pipeline have been estimated due to the potential use of less paint for equivalent corrosion performance compared to existing systems – this would need to be validated in future work. Graphene smart sensors could also save costs by providing early notification of issues. Internal barrier coatings could enable operation of pipelines at higher pressures and/or more aggressive pressure swings than would otherwise be possible, resulting in financial benefits to National Gas. Asset lifetime extension might also be enabled by internal barrier coatings.

·         Safety

o  0% – No direct safety improvement as this is a research project. However, improvements in corrosion management processes via the deployment of advanced coatings could support the maintenance of high safety levels.

·         Environment

o  0.0 tonnes CO2e – No direct environmental benefits as this is a research project. However, improvements in corrosion management processes via the deployment of advanced coatings might enable life extension or avoidance of replacement of assets with associated avoidance of environmental harm. Furthermore, the use of graphene produced by the Levidian Loop system effectively captures carbon from methane and could therefore be considered carbon neutral/negative.

·         Compliance

o  Supports compliance – Work supports transition to hydrogen.

·         Skills & Competencies

o  Individuals – Work will augment knowledge of individuals involved in project.

·         Future Proof

o  Supports business strategy – Work will inform hydrogen repurposing strategies, and could see application in the natural gas network (external paint systems + smart sensors)

Lessons Learnt

This project demonstrated the ability of graphene to be used for corrosion protection, hydrogen embrittlement protection and smart sensing. An important lesson learnt is that graphene shows extraordinary performance when used as a corrosion protection. On the other hand, when graphene is used for hydrogen embrittlement application, it shows relatively good performance to slow down the hydrogen permeation compared to the original coating used (red oxide which is present on the inside surface of the original steel pipes). During this feasibility work, we were not able to obtain a complete block of hydrogen permeation with graphene however the significant drop in hydrogen permeation through the coating used here may be sufficient to provide the expected protection for the pipeline with additional R&D work.

Finally, graphene demonstrated a high sensitivity of its electrical properties under the application of mechanical forces. This means a graphene sensor could be used to detect external mechanical forces applied to the pipeline, including bending, hammering, tapping, torching, and similar mechanical stress. Furthermore, graphene demonstrated the ability to detect temperature and/or humidity, which is another important application of graphene for pipeline sensing.

The deployment of a graphene coating for both corrosion protection and hydrogen embrittlement protection is relatively easy. This could be achieved by using a spray-coating technique, for instance. On the other hand, the deployment of graphene for pipeline sensing will require some planning and designs which will be suitable for the various functions that the smart sensing should undertake, as well as powering the graphene sensors, reading the electrical signals and streaming the data. Some possible solutions are identified, by using existing power line in the pipes, which is currently part of the cathodic protection system and already available on the pipeline.

This feasibility project pushed the boundaries of the initial objectives and demonstrated a positive outcome in all of the project objectives. This would not be possible without the support and guidance of all parties involved and a dedicated representative of National Gas.