What is Corrosion?
Corrosion is usually understood as the process of degradation of a metal or alloy that results in the loss of material. Corrosion processes are thermodynamically driven (i.e. the tendency for a material in nature to transform from a high energy state A to lower energy state B) but kinetically controlled (i.e. the rate of transformation depends of the reaction pathway taken). An obvious example is the observation of ‘rust’, formed through the reaction of exposed steel surfaces in ambient moist air and conversion to more stable corrosion products.
Despite the apparently simple nature of ‘everyday’ corrosion, the process conceals a rich and complex range of phenomena whose causes are varied and whose consequences impact many industries across the globe. For example, corrosion of steel can occur in the presence of hot gases in the absence of water (e.g. high-temperature oxidation, sulfidation and carbonization), through processes that are very different to that for standard ‘wet’ (electrochemical) corrosion. Accordingly, there is no single universally accepted definition for corrosion, but rather different definitions have evolved that reflect the primary concerns of different technology areas and industries. TWI deals with corrosion within many of its industry sectors and, as a Member of The Welding Institute, you can access information and resources specifically related to those sectors.
Industry sectors and corrosion at TWI:
Corrosion of offshore wind turbines is a challenge that is continuously effected by the constant threat from seawater corrosion. This significantly increases inspection and maintenance costs, thereby affecting the affordability of this renewable energy source. TWI offers a range a range of inspection capabilities to detect corrosion related faults as well as expertise in corrosion protection coatings. Examples of TWI’s work includes the development of a phased array ultrasonic testing procedure to enable the volumetric inspection of welds.
Oil and Gas
There are numerous corrosion related challenges in the oil and gas sector, including corrosion of offshore platforms, pipelines and downhole tools as well as further challenges downstream. TWI looks closely at the mitigation of corrosion and offers a range of corrosion testing capabilities, including corrosion under insulation and sour and sweet service testing at ambient or at elevated temperatures and pressures.
Corrosion is also an important consideration for medical implants. Corrosion resistance is an important factor in the ability of a product to continue to function throughout the design lifetime. Corrosion damage leads to reduction in mechanical performance and harmful leaching of chemical species into the patient. TWI offers a range of electrochemical testing expertise which can be applied to simulate in vivo environments.
Power generation can result in highly corrosive conditions such as those produced in biomass power plants from the combustion of variable fuel sources. Typically, damage is experienced on heat transfer surfaces, such as boiler tubes and heat exchangers. TWI has extensive experience in performing tests in aggressive environments such as HCl gas and molten salt. TWI also offers expertise in coating solutions to mitigate the effect of corrosive environments.
Corrosion can present a challenge to the operation of existing bridges and in the design of future structures. Corrosion can result in increased maintenance and inspection costs as well as reduced asset lifetime. TWI offers experience in materials selection, joining and testing to support future construction projects. TWI’s experience with non-destructive testing (NDT) methods and corrosion mitigation technologies provides the opportunity to reduce operational costs and improve asset availability and lifetime.
Corrosion can present a challenge in the automotive industry, due to material performance and aesthetic requirements. TWI offers support to Members through reducing costs, developing innovative solutions and adding functionality to their products/services. More specifically, the improved wear or corrosion performance through coatings and surface modification. Surface engineering affects the chemistry and properties of the surface layer of the asset. Weld hardfacing and other cladding processes are used for wear or corrosion resistance and repairing damaged parts.
For safety critical industries such as aerospace, corrosion risks are particular important. Due to the range of different operational environments experienced by aircraft components, a wide variety of corrosion (and cracking) damage modes can occur. As for the automotive industry, TWI offers services in wear or corrosion performance through coatings and surface modification to help in the aerospace industry.
TWI Software offers different software products suited to corrosion engineers to analyse the risk of corrosion and the integrity of components impacted by corrosion.
RiskWISE assesses the risk of corrosion occurring in pressurised equipment including pressure vessels, piping, pipelines, tanks, etc. The software calculates the probability of failure (PoF) as well as the consequences of the failure of components/structures. RiskWISE is a risk-based inspection and risk-based-management engineering software. It enables engineers to ensure the continued safe and economic operation of the equipment/plant in line with relevant industry standards. To find out more about TWI RiskWISE software, please click here.
IntegriWISE is a plant life management software that assesses the fitness-for-service (FFS) of high pressure equipment, looking at the severity of different damage mechanisms, including pitting and general corrosion. It calculates and records the fitness-for-service of industrial equipment and plant, including ageing pipework, pipelines, storage tanks, and pressure vessels. The software assesses if the component/equipment is suitable for continued use at the specified operating conditions. To find out more about TWI IntegriWISE software, please click here.
Membership of The Welding Institute
Membership of The Welding Institute holds many benefits for you as a corrosion engineer. Registering as a Member of The Welding Institute provides you with professional recognition separate to your employment.
As a corrosion specialist, the Institute will be able to support you through your registration process with our different industry sector specialists volunteering as mentors to help new Members.
As a Member of the Institute, you can attend Technical Group Meetings (TGM) where developments in the technology and the practice of specialist areas, such as corrosion, are discussed. Technical group meetings are held throughout the year and are an excellent opportunity to network and gain contacts that can aid your career development. Another benefit of TGMs is the continuous personal development points that you can gain from attending them, whilst gaining valuable industry knowledge.
The Welding Institute also offers other events related to corrosion, click here to find out about the events that The Welding Institute offers.
Other membership benefits that you as a corrosion engineer can benefit from include the ability to access other TWI resources including its Technical Library containing technical information, journals, research papers and more, relating to corrosion.
As a Member of The Welding Institute you can access corrosion related training courses with TWI Training and Examinations, at a 5% discount.
Read The Welding Institute's 'Training and Examinations - Corrosion' Insight to find out more about the training courses provided by TWI Training and Examinations.
The Wales Skillweld Competition 2020 was hosted by Neath College on 6 February, 2020.
This first stage of the competition is called the Passive Heat round and involves candidates completing a list of welding geometry. This round is an excellent opportunity for candidates to gain both practical and competition experience which, in turn, will help them in future rounds of the competition including the National Qualifiers and National Finals.
Candidates of the Wales Skillweld competition were tasked to complete four weld types. The first involved using the welding process of MAG to produce a tee fillet plate in the PF welding position. The second task was to use the MMA welding process to weld pipe to plate in a PB welding position. The third task involved using the TIG welding process to produce a tee fillet plate in the PC welding position. The final task was to use the TIG welding process to weld pipe to pipe in a PC position.
Judges of the competition have commented on the high levels of skill displayed by competitors at this first level and said that it was a promising start for many candidates for when they entered the higher rounds. They commended the overall production of good quality weldments and noted that all competitors should be proud of their accomplishments.
The Skillweld Competition is an excellent way for a new generation of welders to develop their skills and learn from experienced personnel within the welding field.
Fitness-for-Service (FFS) (also referred to as Fitness-for-Purpose) is an assessment that is carried out using the best-practice industry standards. The FFS assessment evaluates the structural integrity of an asset/component to determine whether the asset/component is suitable for its intended use. The Fitness-for-Service (FFS) assessment provides a quantitative measure of structural integrity and is part of asset integrity management. The assessments are used to highlight the need for replacement or repair of assets/components.
Fitness-for-Service is important at both a low level (during screening assessments) and also at a high level. The assessment at a low level can highlight if equipment is fit for continued use when limited data is available, therefore saving both money and time repairing or replacing equipment. Higher assessment levels require more data and cost more money than lower level assessments. All levels of a Fitness-for-Service assessment are used [during the] [as part of the] lifetime of a power plant to increase availability, reliability, efficiency and safety.
Fitness-for-Service assessments are used to assess the structural integrity and suitability of a component/asset for its intended use. This allows the process to be used to assess critical pressure components and welded structures. The process is used throughout various stages of an asset’s life, including design, fabrication and operation, to identify mitigation processes needed for the safe continued use of assets/components.
Fitness-for-Service is used within many different industry sectors, including oil and gas, power generation, chemical processing and aerospace. Examples of where TWI has carried out Fitness-for-Service assessments within these industries include:
A Fitness-for-Service assessment based on damage that was present was carried out by TWI on a cross-country pipeline. Click here to find out more.
TWI carried out a Fitness-for-Service assessment in response to a small root undercut detected in a pipeline. Click here to find out more.
Fitness-for-Service assessment used for a high pressure piping system after the presence of flanges were discovered. Click here to find out more.
TWI subsidiary, Plant Integrity Ltd (PI) used a variety of assessments including Fitness-for-Service to inspect over 5,300m of pipeline. Click here to find out more.
Assessments including Fitness-for-Service were carried out on an oil well for a major offshore oil and gas operator. Click here to find out more.
A Fitness-for-Service assessment was used to assess high hardness values in weld zones of a stainless steel pipework. Click here to find out more.
Fitness-for-Service was used to investigate a subsea pipeline dented by the anchor of a tanker. Click here to find out more.
Corroded wood pulp digestors assessed using Fitness-for-Service. Click here to find out more.
TWI Software offers various software that assist with fitness-for-service assessments, these include:
IntegriWISE™ – This software allows the integrity of storage tanks, pipelines, pressure vessels, boilers and high temperature equipment to be assessed. It achieves this by assessing damage mechanisms and creating ‘what if’ scenarios. To find out more about IntegriWISE™ click here.
CrackWISE® - This software helps to ensure the continued safe operation of pipelines, structures and pressure equipment by helping evaluate flaws. To find out more about CrackWISE® click here.
RiskWISE – This is an integrity management software that is used on process plants, boilers and pipelines. This software is able to process large quantities of data related to risk-based inspection techniques. To find out more about RiskWISE click here.
Becoming a Member of The Welding Institute offers you access to a range of membership benefits. These benefits have been designed to support your professional progression within your career as an engineer. Although our name suggests that we only register welding and joining engineers, we do offer membership to all engineers and therefore offer membership benefits that are suited to you. These benefits include:
Click here to view all membership benefits.
Most households have an unsolved Rubix Cube but you can esily solve it learning a few algorithms.
The Skillweld Competition 2020 is now open for registrations!
This Skillweld Competition has been created to assess the skills of trainee welders in three manual fusion processes. They will be required to complete and produce four weld tests.
The aim of the Skillweld Competition is to promote the development of a skilled workforce that will be equipped to meet the needs of the UK welding industry. It is an excellent opportunity for students and trainee welders to learn new skills and gain hands-on experience of the practical application of these welding processes.
To help trainee welders develop their welding skills in a competitive and pressurised environment
Through allowing your employees/learners to compete in the Skillweld Competition, you are enhancing their experience and knowledge within welding and therefore also investing in the future of industry.
Closing date for competition entries is 27th March, 2020.
To find out more about the Skillweld Competition, click here!
Click here to enter!
The Welding Institute is proud to support apprenticeships and their ability to develop capable individuals into having successful careers within the engineering industry.
National Apprenticeship Week is an annual week where apprenticeships and apprentices are celebrated and recognised throughout England. It looks at the successes and inspirational stories of apprentices and enables employers to promote the benefits of employing apprentices.
As one of the members of a number of ‘Trailblazer Employer Groups,’ The Welding Institute is able to encourage the current and future development of trailblazer standards including the:
Apprenticeships are beneficial to both the apprentice and the employer. They are an excellent opportunity for apprentices to get into a career that they are interested in whilst gaining official qualifications (which will later help them progress once their apprenticeship has been completed).
At the same time apprenticeships allow employers to gain a dedicated employee who will be gaining industry knowledge and qualifications at the same time, which in turn will be utilised within their work.
It is vital that we encourage individuals to pursue a career in engineering due to the need and demand to fill future engineering jobs. Engineers play an incredibly important role within society, and The Welding Institute are dedicated to inspiring people to take on this career path. The Welding Institute’s Younger Member Network is dedicated to representing the interests of younger members, and developing the next generation of engineers. Members of the network promote the importance Professional Registration and Continuous Professional Development (CPD). Members who are also STEM Ambassadors participate in STEM outreach activities at primary and secondary schools, colleges and universities.
The Welding Institute’s Southern Branch and AWFTE will be jointly hosting a forum focusing on the ‘Technical Challenges and Innovations in Welding Engineering.’ The event will be hosted by Portsmouth University on 13 March, 2020. It will cover topics including marine engineering, materials welder training and education in Southern England.
The day will include technical presentations and talks from industry experts, discussing new and existing applications, including current research projects. There will also be an opportunity for attendees to put questions to an expert panel. Attendance of this event is an excellent opportunity for those in the education and employment sectors with an interest in training and developing their career within the welding engineering industry.
To find out more about this event, please follow this link which will redirect you to the TWI Ltd global site where you can also register for the event.
View the most recent programme here.
Welding is a process where two or more parent materials are joined through heat and pressure. Heat and pressure can be applied together or individually to form a weld.
The parts being joined through welding are known as the ‘parent materials,’ the material added to help create the join is known as the ‘filler’ or ‘consumable’ and the result/final form is called the ‘welded joint’ (the final weld may also be referred to as a weldment).
Different welding processes are carried out to produce high quality welds by joining metals, wood and other materials.
When choosing the consumables or fillers, it is important to consider the materials that you are joining/welding together. There are two types of welds:
Homogenous welds – this is where the consumables or fillers being used are similar in composition to the parent materials.
Heterogeneous welds – this is where the consumables or fillers being used are dissimilar in composition to the parent materials.
When welding with heat, the parent material (often a base metal) can either be used independently or with the presence of a consumable or filler material (often filler metals) to produce a weld pool consisting of molten material, which cools to form a weld.
Pressure welding involves applying a specific level of pressure onto a parent material to form a weld.
Both welding processes can be performed with or without the presence of each other, depending on the material being welded. Some welding processes require both heat and pressure whilst others only require one of them.
TWI has significant experience in welding and joining technology research and has been responsible for developing the production and adoption of new techniques. The techniques that TWI have developed extensive technical knowledge on are:
Arc welding is a fusion welding process that is used to join metals. The process involves an electric arc from an alternating current (AC) or direct current (DC) to create heat that melts the material (usually the base metal) at the join between the parent materials. This technique may also use a filler material (or filler metal). To find out more about arc welding click here.
The arc welding technique has different variations including; tungsten inert gas welding (TIG), metal inert/active gas welding (MIG/MAG), manual metal arc (MMA) welding, submerged arc welding (SAW), plasma arc welding, hybrid laser-arc welding, and underwater welding.
Electron Beam Welding
Electron beam welding (EBW) involves using a beam of high velocity electrons to join parent materials. The kinetic energy of the electrons creates heat when they come into contact with the parent material(s). This causes the parent material to melt and form a join. This process is carried out in a vacuum to help prevent the dissipation of the beam. The technique is often used for the joining of thick/larger materials. TWI’s involvement in electron beam welding in relation to industry includes design, selection, troubleshooting, trialling, application and development. TWI’s work includes the research of in-vacuum-chamber electron beam (EB) welding, out-of-vacuum-chamber electron beam (EB) welding, non-additive processing, EB additive manufacturing, advanced equipment and QA solutions.
This welding process joins parent materials through the use of mechanical friction and can be applied to materials such as stainless steel, aluminium and wood. This process does not need a filler material and can be carried out with or without it. Variations of friction welding include friction stir welding (FSW), linear friction welding (LFW) and rotary friction welding (RFW).
Laser beam welding is a welding process used for the joining of metals, thermoplastics and other materials. The laser creates a concentrated beam of heat, therefore allowing the technique to be used in narrow and deep welds at high volume rates. This process differs to electron beam welding because it does not need to be carried out in a vacuum. Laser welding is used in different industry sectors including power, automotive, medical, shipbuilding and aerospace. TWI’s technical knowledge includes; laser welding, hybrid laser-arc welding, laser brazing, laser cutting, laser surface engineering, laser processing of polymers, decommissioning using lasers, laser metal deposition (LMD), selective laser melting (SLM) and laser process monitoring for quality control and assurance.
Resistance and Mechanical Welding
Resistance welding is a welding process where metals are joined through the application of pressure and the passing of a current for a specific length of time. The heat causes the parent materials to melt at the joint as the pressure causes the parent materials to join together and form a weld. Techniques that TWI have expertise in include resistance spot welding, resistance projection welding, resistance seam welding, flash and resistance butt welding, high frequency welding and micro and miniature resistance welding. Click here to see what services TWI offer in mechanical fastening.
Although The Welding Institute offers Professional Membership to all engineers, our expertise in the welding and joining industry are a significant part of the Institute’s history (view the Institute’s history here). We are still the leading professional body for the registration of welding and joining personnel and can offer over 70 years of experience in welding and joining. Benefits of this expertise includes:
One of our main benefits as an Institute is being able to offer a 5% discount on all TWI Training and Examination courses to our Members. Why not consider come of the following courses?
They also offer a range of Welding Appreciation courses including:
TWI Training and Examinations also offer a range of CSWIP Welding Inspection Courses. Visit their Welding Inspection page to find out more about this internationally recognised certification.
Continuing Professional Development (CPD) is the process of recording your professional learning and experiences. As a Member registered with the Engineering Council, you will have to carry out CPD.
CPD advocates the importance of professional development to ensure that you are able to demonstrate your knowledge and experience of up-to-date industry standards and practice.
Continuous Professional Development is compulsory for all members registered with the Engineering Council with the potential risk of losing your Membership of The Welding Institute/registration with the Engineering Council. As of January 2020, your CPD records may be sampled by your institution to ensure they have been kept updated.
It is an important source that can be used as a reference when making contacts throughout your career. Having a record of your development (such as CPD) gives your clients, employers or employees confidence and assurance in your competence and ability.
Due to the nature of the engineering industry continuously changing, having an evidenced record of your continued development demonstrates that you are up to date with industry standards.
The Welding Institute offer a certificate for anyone achieving 100 CPD points within a year.
Overall, CPD is a source of competence evidence. Across your engineering career, you will work over a broad variety of topics and projects, but having CPD enables you to keep track of this.
Why is CPD important?
The aim of CPD is to demonstrate that, although you may have finished your formal education, it is important to continually learn and advance your knowledge to ensure that you can evidence your knowledge, at your work, of up-to-date industry standards and practices whilst remaining competent.
Check out our Continuous Professional Development Brochure for more information.
The Welding Institute understands the importance of your career development as an engineer involved with magnetic particle testing. We are able to support your career development through our Member benefits. These include:
As a non-destructive testing (NDT) engineer, technician or personnel engaged in magnetic particle testing, we can support your career development through giving you access to the following TWI Training and Examinations course:
Magnetic Particle Testing (MT) - this course looks in detail at the process of magnetic particle testing and the application of this NDT technique.
TWI Training and Examinations can also support for your career progression as a non-destructive testing (NDT) engineer, technician or personnel through the Non-destructive testing (NDT) Levels 1, 2 and 3 course overview page.
Also make sure that you take a look at the career path that you can take from completing these training courses here.
What is Magnetic Particle Testing?
Check out our Insight: What is Magnetic Particle Testing? - A Definitive Guide.
Magnetic Particle Testing, also known as Magnetic Particle Inspection (MPI) is the process whereby a component is magnetised to produce lines of magnetic flux within the component. When the lines of flux meet a discontinuity that lies in a generally perpendicular orientation to the direction of flux flow, a flux leakage field is formed at and just above the component surface. The flux leakage is revealed by the use of finely divided ferromagnetic particles that are caused to flow over the surface, some of which are gathered and held by the leakage field. These magnetic particles, which may be either in the form of a powder (dry) or in a liquid suspension (wet), are used to form an outline of the discontinuity and indicate its location, size, shape and extent.
Methods of Magnetisation?
There is essentially two methods of producing a magnetic flux within the component under investigation. A flow of magnetic flux can be generated by introducing an external magnetic field into the component from a source such as a permanent magnet, an electro-magnet or a current carrying conductor adjacent to the component or formed into a coil. Alternatively, an electric current can be passed directly through the component that will induce a magnetic flux into the component, which is perpendicular to the direction of the current flow. The current waveform used can range from DC to full AC. As a general rule, AC is very sensitive to surface breaking discontinuities, while DC has the potential to detect slightly subsurface discontinuities.
Dry and Wet Magnetic Particles
The particles used in magnetic particle testing are important in indicating discontinuities within a test part. The properties of the magnetic particles used in magnetic particle testing need to include high magnetic permeability (the ability to be magnetised) to allow the particles to be attracted to the magnetic flux leakage fields and low retentivity (ability of particles to retain magnetisation) to prevent the particles from attaching to each other or the surface of the component. There are two types of magnetic particles used:
Dry magnetic particles – this method involves using a variation of particle sizes to indicate different sizes of flux leakage sites. Smaller particles are more sensitive to flux leakage sites/fields and are therefore able to identify smaller defects/flaws and larger particles are able to identify larger flux leakage sites.
Wet magnetic particles – this technique includes magnetic particles being suspended in a substance such as water or oil. This method is more sensitive to flux leakage sites caused by defects and flaws than dry magnetic particles due to the particles being more mobile whilst in a suspended state. This method also allows a larger surface area to be covered, therefore indicating more flux leakage sites.
Magnetic particle testing is a non-destructive test method, which can be used to inspect a variety of ferromagnetic components and products. These include castings, forgings and weldments. The method is used across different industry sectors, especially when determining if a component is fit-for-service. Industries that use magnetic particle testing include, aerospace, automotive, marine, power, oil and gas, components and structures, engineering and fabrication.
TWI have used their 40 years’ of experience to develop a wide variety of non-destructive testing (NDT) techniques and have provided services within the industry related to magnetic particle testing. Examples of this work include:
Components and Structures
TWI inspected a component within a mechanical system using magnetic particle inspection to detect surface or near surface flaws or defects.
TWI investigated the technique of warm prestressing. TWI looked at the effects of these pressure tests and how they impact the tests that are carried out throughout a component/structure’s life. This article also looks at the uses of the magnetic particle testing performed within this research.
The Magnetic particle inspection method was carried out by TWI to investigate a welded manifold valve (a component/piece of equipment that connects valves of a hydraulic system).
A TWI Industrial Member requested support in developing an NDT procedure for hot tapping subsea oil and gas under hyperbaric conditions. TWI investigated the appropriate NDT techniques and recommended magnetic particle testing.
TWI used magnetic particle inspection to investigate the internal blistering of an oil pipeline for an Industrial Member.
TWI investigated propeller hubs of an aircraft using magnetic particle inspection.
Magnetic particle inspection is used within the marine industry including FSPOs (floating production, storage and offshore loading vessels).
TWI carried out inspection of lift eyes (also known as pad eyes) welded onto a module being lifted onto an offshore platform. Magnetic particle inspection was carried out on the lift eyes before and after they were welded onto the module.
Engineering and Fabrication – Bridges and Infrastructure
Magnetic particle inspection was one of the non-destructive test methods carried out during the inspection of electroslag (ES) welds on a network critical structure prior to the 2012 Olympics.
TWI inspected a repaired reactor at a nuclear power station using magnetic particle inspection. TWI’s main responsibility was to ensure that the repaired component was free from defects including surface and sub-surface cracks.
The Welding Institute
As a Member of The Welding Institute you have access to our membership benefits. As an engineer, technician or personnel engaged in magnetic particle testing The Welding Institute has benefits that can support you, these include:
Click here to view all of our Membership Benefits!
Magnetic Particle Testing Training Courses
Check out our Magnetic Particle Testing – TWI Training and Examinations Insight to find out more about the courses that TWI Training and Examinations offer!
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