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Analysis of workers exposure to electromagnetic fields (EMF) from welding and NDT processes, guidelines for risk assessment and development of risk assessment web based application

Final Report Summary - EMFWELD (Analysis of workers exposure to electromagnetic fields (EMF) from welding and NDT processes, guidelines for risk assessment and development of risk assessment web based application)

Executive Summary:
The recently published EU Directive 2013/35/EU has introduced limits for electromagnetic fields (EMF) to which workers are be exposed. These limits shall not be exceeded, due to concerns about adverse health effects. All employers within the European Union need to ensure that their employees are not exposed to EMF above these limits by the time the legislation comes into force in June 2016. It is believed that the European fabrication industry will be significantly affected by this legislation, because welding processes are known to be high emitters of EMF, due to the magnitude and frequency of the currents involved.

The SME association/groupings (SME-AGs) in this transnational consortium wished to develop an interactive web-based software application to calculate and assess EMF exposure in metal fabrication, particularly welding and non-destructive testing (NDT). There is a recognised lack of knowledge in these sectors concerning the sources of EMF and its comparison to set exposure limit values, particularly for the new EMF Directive. Without clear guidance and support, SMEs in the fabrication industry will be put at a competitive disadvantage as they incur a heavy and disproportionate financial cost in order to meet the required standards and ensure a safe working environment for their workers. EMFWELD will significantly lower SMEs’ cost of compliance to Directive 2013/35/EU by providing an innovative, economic and easily accessible accurate EMF exposure risk assessment tool.

The envisaged software application required expertise and extensive research and understanding of welding processes and their associated EMF parameters; EMF exposure health effects, and software development. The SME-AGs of this consortium simply did not have the necessary research capabilities and therefore engaged leading RTD performers (RTDPs) with world class knowledge in welding processes (TWI) and simulation of EMF health effects (CHALMERS), to develop the EMFWELD concept.

EMF waveforms were measured for the major welding processes and magnetic particle inspection. These waveforms were used for calculation of workers compliance to the Action Levels (ALVs) and Exposure Limit Values (ELVs) specified in the Directive.

A web-based software toolkit was developed to enable SMEs and other companies to make an EMF assessment without the need for measurement or modelling.

In addition to providing decisive cost benefit for the SMEs, EMFWELD will also contribute towards the establishment of new EU standards for the assessment of EMF in metal fabrication industries promoting a safe working environment and benefiting Europe as a whole.

Project Context and Objectives:
The EU Directive 2013/35/EU on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) (20th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC) and repealing Directive 2004/40/EC was published on 26 June 2013. This Directive has introduced limits for electromagnetic fields (EMF) to which workers are be exposed. These limits shall not be exceeded, due to concerns about adverse health effects. All employers within the European Union need to ensure that their employees are not exposed to EMF above these limits by the time the legislation comes into force in June 2016. It is believed that the European fabrication industry will be significantly affected by this legislation, because welding processes are known to be high emitters of EMF, due to the magnitude and frequency of the currents involved.

The EMFWELD project started in October 2012 in anticipation of this Directive, because the fabrication industry, guided by EWF and CEEMET, were aware of the significant impact that this legislation could have on the European industry. At that time it was not known how long the transition period would be, but it was suggested that it could be as short as one year, anticipating compliance in October 2014.

The EMF Directive introduces new exposure limits, so very little information was available on exposures likely to be encountered in the fabrication industry. The industry had an immediate need to gain a better understanding on how the emissions from welding and inspection processes would compare to these limit values and what the likely impact would be on European Industry. This was not a simple process because the Directive introduces both levels for the external field and the internally induced field that cannot be measured. Although with the right equipment an assessment can be made of the external field with respect to defined Action Levels (ALs), an assessment against the internal field Exposure Limit Values (ELVs) requires mathematical modelling and calculation, beyond the capabilities of most organisations.

Furthermore, it was recognised that it is not a simple task to carry out an EMF assessment. It requires knowledge, skill and the right equipment to carry out even a simple assessment against the ALs. If these ALs are found to be exceeded, a more detailed assessment against the ELVs is required, but this requires specialised software and considerable expertise, as can only be found in some universities and scientific organisations. So, in addition to the measurement and calculation of EMF exposure, a key objective of the EMFWELD project was to create a software toolkit to enable EMF assessments to be carried out simply and cost effectively by SMEs and other companies involved in welded fabrication.

Scientific Objective
The principal scientific objective of EMFWELD is to increase knowledge and understanding of EMF in welding and magnetic particle inspection MPI processes; its sources, assessment and effects on those exposed. This will enable the creation of tools for its effective assessment within the fabrication environment by meeting the following objectives:

Technical Objectives
• To develop detailed maps of EMF fields for up to 10 welding processes and one NDT process, with associated process parameters, for a range of different parameters and configurations. The following welding processes will be mapped; Manual metal arc; Metal inert gas/metal active gas; Tungsten Inert Gas; Submerged arc; Resistance spot; Resistance seam; Stud welding; RF welding; Induction heating/brazing and Magnetic Particle Inspection
• Establish and map the waveform of the current (amplitude frequency components and phase) of each the 10 processes over a range of operating conditions and equipment configurations
• Generate model and simulations of the EMF field from the mapping data for each of the 10 processes
• Calculate human exposure based on measurement and calculation and produce rules for assessment of exposure in different operator positions for each of the 10 processes
• To produce a software toolkit for assessing exposure when an operator is placed in a particular position in a simulated workplace using a set of welding parameters with following functionality;
o Able to simulate workplaces with true models of welding equipment
o Able to simulate welder/operators in real life positions
o Able to assess the risk of human exposure based on the simulation models.

Economic Objectives
The overall economic objective of EMFWELD is to reduce the cost of EMF exposure assessment in fabrication and NDT processes, specifically in welding and MPI. Specifically, we aim to
• Reduce cost for SMEs familiarisation with EMF assessment by 75%
• Reduce cost of assessment in the welding environment by 40%
Project Results:
This two year project started in October 2012, before the EMF Directive had been finalised. At that time, after several postponements, it was clear that the Directive would go ahead and publication was anticipated in October 2013, with potentially enforcement in October 2014, to coincide with the completion of the project. The Directive was published but slightly earlier the expected on 26 June 2013, to be transposed into national laws by 1 July 2016.

So, although the details of the legislation were not available at the start of the project, it was clear from the knowledge of previous versions of the Directive and from ICNIRP guidance that measurement and modelling of the EMF would be required.

The goal of the project was to create a software toolkit to assist companies, especially SMEs, with carrying out an assessment of exposure to EMF. To do this a comprehensive data base of levels of EMF for different processes, equipment and operator positions would be required. It was also known form previous studies that because the magnetic field can be high in welding, modelling and simulations would be required to fully assess exposure. However, what was not confirmed at the start of the project, was the actual limits that would be applied in the Directive and the approved method of assessing the waveforms.

Work started by reviewing published literature on EMF in welding, together with relevant legislation and recommendations. The legislation is mainly previous drafts of the Directive and recommendations on exposure are published by ICNIRP and IEEE in the USA. The basic specification for the software was also agreed although some details were confirmed later in the project. The software specification evolved as data collected and analysed.

Work then started by carrying out extensive measurement of the magnetic field waveform for a range of different processes. At this point is was agreed with the partners that RF welding would not be included as this operates at much higher frequencies that the other processes and would require different instrumentation and analysis techniques. Waveforms of the magnetic field were recorded using a NARDA ELT-400 magnetic field probe coupled to an oscilloscope, over a frequency range of 1Hz-400kHz. Sampling rates (1MHz) on the oscilloscope, were chosen to accurately record the frequency component of the waveform.

Waveforms for the following processes were measured;
• Manual Metal Arc (MMA) welding
• Metal Inert Gas (MIG) welding – dip mode
• Metal Inert Gas (MIG) welding – spray mode
• Metal Inert Gas (MIG) welding – pulse mode
• Tungsten Inert Gas (TIG) welding – pulsed DC mode
• Tungsten Inert Gas (TIG) welding – AC mode
• Single phase resistance AC welding
• Medium frequency resistance welding
• Stud welding
• Magnetic particle inspection
• Induction heating

Measurements were made on more than type of equipment and at different settings to get representative samples of the magnetic field. Some measurements needed to be repeated as the project progressed to improve the quality of the data and also to fill in some gaps.

A database of waveforms exceeding 900 entries has been produced.

The magnetic waveforms were then passed through digital filters to assess against the ALs. In the Directive there are three ALs, low, high and a separate one for limbs. These digital filters were derived from the frequency dependant AL values given in the Directive. This provided a waveform factor to be used in the assessments.

SEMCAD X, commercially available software, was used to map the magnetic field in 3D space around specific geometries, eg resistance welding guns of various heights and reach, at a normalised current of 1A. By multiplying the values obtained by the welding current and the waveform factor derived from the digital filters an assessment against the ALs is obtained with a value less than or equal to 1 (100%) demonstrating compliance.

In total over one hundred field maps of the magnetic field were generated in the project.

As shall be explained later, these field maps are provided in the software and enable the user to make an assessment very easily. The software package can also be used to access and review all the data collected and processed in the project.

If the ALs are exceeded, it is necessary to make an assessment against the ELVs. This is not a simple task and requires complex modelling and simulation. In this project this was carried out using the SEMCAD X software and the results obtained are extremely valuable, as many hours are required for each assessment.

SEMCAD X was used to calculate a coupling factor for specific equipment geometries and operator positions and configurations. Simulation can only be carried out at one frequency at a time, but fortunately over the low frequency range considered tissue conductivity is approximately constant, so a result can be applied to the full range up to 400kHz being considered. The results obtained apply only to that specific scenario so cannot be mapped in 3D space. The Duke phantom was used in the modelling because it is large and produces a conservative estimate. The solver setting was “Low frequency magneto quasi-static”. This solver calculates the conductive current, which dominates over displacement currents for low frequencies. The resulting electric field strength was obtained as the rms value averaged over a 2x2x2 mm volume as proposed in the ICNIRP 2010 Guideline. The voxel size in the simulations was 1x1x1 mm.

The next step in the process was to digitally filter the magnetic field waveforms using other new filters derived from the frequency dependant values for the ELVs given in the Directive. Two filters are required, one for sensory and one for health effects. This produces new waveform factors used for the ELV assessment.

By multiplying the welding current by the waveform factor and coupling factor an assessment can be made against the ELVs.

The value of these results is very high because it can be demonstrated that for some exposures that exceed the ALs, the ELVs are not exceeded and the process is in compliance. For example calculation shows that for medium frequency resistance welding at 25,000 A and a distance of 300m the AL is 147%, but the sensory ELV is only 17%, so the equipment is in compliance.

Over 100 scenarios have been modelled representing a range of typical scenarios for each process.

The main result of the project is a prototype web-based software toolkit that will enable SMEs to make easy and cost effective risk assessments for EMF exposure as required by the EMF Directive. The software enables an EMF exposure assessment to be made for arc and resistance welding processes, stud welding, induction heating and magnetic particle inspection. An assessment is made against the Action Levels and Exposure limit values in the Directive and a report is produced which provides guidance on interpretation and any actions that may be necessary.

The software development was broken down into several tasks:
• Construction of a flowchart that represents the path of an assessment through the Directive, taking account of the various exceptions and alterations which are situation dependent eg workers at special risk
• Creation of a mathematical process that allows the software to perform assessments against the directive based on the potentially limited information a user will provide.
• Construction of the software to a prototype level such that the future development of the software can be planned making use of the information gained during this development stage

The software consists of two major components. The first is the “back-end” which contains the database of field measurements, the coupling factors calculated by Chalmers and the method of assessing these components against the levels. The second component is the graphical user interface which allows the user to make an assessment.

The software is web based and access by the following link www.emfweld.eu . Users require a user name and password to access the programme. The assessment report are saved under the specific user name.

The prototype software has been developed in ASP.NET 4.5 using Webforms technology. The application code is written in C#. Development is being performed using Visual Microsoft Studio and Microsoft Internet Explorer 10.

Data is held within an integrated SQLServer 2012 database. Data consists of a series of look up tables for processes and configurations. This data includes field maps, waveform factors and field factors.

To perform an assessment against the ALs the operation performed by the software is:
• Take user input – process
o Get waveform factor
• Take user input – geometry
o Get field factor
• Take user input – current
o Get rms current

The software then performs the assessment calculation for every point specified throughout 3D space:
% action level=waveform factor (%/uT)×field factor (uT/A)× rms current (A)

From this a series of field maps are displayed, showing the maximum field in each plane the values of the ALs at a specified point in space are provided.

Similarly, to perform an assessment against the ELVs the operation performed by the software is;


Take user input – process
Get waveform factor
Take user input – geometry
Compare to held geometries
Get coupling factor
Take user input – current
Get rms current

The software then performs the assessment calculation for every point specified throughout 3D space:
% exposure limit value=waveform factor (%/uT)×couplingfactor× rms current (A)

In this case the software is not able to generate field maps with different zones due to the coupling factor being an important part of the calculation. However, in some cases, it is possible to perform the assessment calculation with multiple coupling factors where there have been calculations performed with the same equipment geometry but different operator positions. This allows the software to offer a range of operator positions that might not exceed the exposure limit values.

The ELVs at a specific point in space are provided as necessary. If the ALs are not exceeded then no ELVS are required. If the low AL is exceeded, the sensory ELV is given and is the high AL is also exceeded the health ELV is also displayed.

Guidance is provided on the actions to take depending on the outcome of the assessment.

The graphical user interface (GUI) has been developed to make it easy for the user to input the necessary data, with drop down options, lists and graphics showing equipment and cable locations. Individual pages of information are provided and the user can move between those pages. The software has been written to make translation into different languages simple and at present, English, French, German, Italian, Swedish and Portuguese can be selected.

The web based software enables SMEs and other companies to make a cost effective EMF assessment of welding processes and MPI.

The software has been tested and validated both internally and externally.

Formal testing was conducted using a ‘black box’ methodology. External stimuli were applied to the software and the effects were noted. These were compared against the original functional specification for correctness. Valid and invalid data was entered in order to ensure correct operation of the application. Code coverage tools were employed during unit testing rather than formal testing as coverage tools were more readily available. EMFWeld does not expose an API this so was not covered.

Multi-platform testing was performed by running the application on different devices (computers – Windows & OSX and mobile devices – Android and IOS). Also, the user trials found some incompatibilities with user environments which were rectified during development.

The results of the assessments were compared to measurements carried out first in the laboratory and then during field testing at the Inaceinox, SME partner. Validation was carried out for resistance and arc welding processes. The results obtained from the software were compared the ALs measured directly using a NARDA ELT 400 instrument with the appropriate filters built-in. In most cases there was good agreement between calculation and measurement ad in all cases the software provided a conservative estimate of exposure. Validation of the modelling results for ELVs can only be carried out by comparing the results with those obtained by other experts. This was outside the scope of this project but Chalmers University are actively exchanging results with other s within their academic community.

Final testing of the software took place as an additional activity that was not originally planned for in the DOW. User names and password were generated for a selected group of EWF and CEEMET members. They were asked to provide feedback through an online survey and they comments helped to resolve a number of bugs and typographical errors in the software. This feature has been retained in the final version of the prototype software.

Adding to this the development of a Training Guideline as well as training materials (like videos, tutorials, manuals and presentations) will allow a wider dissemination of the EMFWELD project after the end of it. This Training Guideline and the update of the EWF Guidelines will ensure that the project results will be used in the future.

In summary, a prototype of the EMFWELD web- based software toolkit has been developed which assists SMEs and other companies to make an assessment of workers exposure to EMF as required by EU Directive 2013/35/EC. This software is based on;

• A database of magnetic waveforms exceeding 900 entries.

• Over one hundred field maps of the magnetic field for assessing compliance to the Action Levels over a wide range of welding currents

• Modelling of over 100 scenarios to make assessments for compliance of typical welding configurations to the Exposure Limit Values.


Potential Impact:
The new EU-Directive on Electromagnetic Fields (2013/35/EU) was published in the EU’s Official Journal on 29 June 2013. The consortium has been closely monitoring the legislative process, while inputting expertise on behalf of the sector we represent and contributing to the review process with all EU institutions. The new Directive sets down the requirements and the impact it will have on risk assessments and limit values. With the implementation of this new Directive European manufacturing industry will have to make sure that the processes, including the welding processes, comply with it.

There are currently no existing reasonably affordable tools for carrying out an EMF risk assessment, particularly for SMEs. Measurement using dedicated instruments can be used to assess the instantaneous magnetic field against the low action levels, but this is both time consuming, expensive and results in a conservative assessment. There is therefore a large gap in the market for this software toolkit.

There are estimated to be 4 million people working in the metal fabrication industry in Europe. A survey of CEEMET members resulted in approximately 20,000 companies who may have a use for this software. These companies employ approximately 130,000 workers who work in the fabrication industry.

Assessment of workers exposure to EMF is expensive, requiring a knowledgeable person and the use of specialised equipment. Site surveys can cost on the order of several thousand pounds. The software toolkit aims to reduce the cost of assessment significantly, to improve the competitiveness of SMEs in Europe

All of these factors combined guarantees the impact of the EMFWELD project, mainly when the Electromagnetic Field Directive becomes law in the European countries. The idea of a new, so far non-existing product for companies in order to check their compliance with certain welding processes and EMF related H&S regulations (“risk analysis”) is a guarantee of the expected high impact of the EMFWELD project.

Since the beginning of the EMFWELD project all partners showed a great commitment in disseminating the project results, not only during but also after the project end. This is easy to evaluate based on the 58 dissemination activities carried out. The type of activities was very broad, from the participation in conferences, to face-to-face meetings, magazine articles, flyers, posters and workshops. It was also impressive to have more than 3000 visits to the EMFWELD website during the duration of the project. EWF and CEEMET also prepared a media kit that enabled both association organisations to map out project information. This media kit was circulated to members of both organisations and enabled the SME-AG’s to explain the most current developments to their membership. Adding to this the reference to EMFWELD in the EU practical guide and the update of the EWF training guidelines to include reference to the EMFWELD project are just some examples of how the dissemination of the EMFWELD project will carry on after the end of the project.

Adding to this a Training Guideline was also developed during the duration of the EMFWELD project. This Training Guideline will be included in the EWF Harmonized Training System, allowing the access to it by different partners accross 30 European Countries. This new Tranining Guideline will be used to train personnel on the Directive but also on the behaviour of ElectroMagnetic Fields in Welding bridging a Qualification Personnel gap that will appear when the Directive becomes mandatory at the National lever and by doing so create new jobs in companies, mainly SMEs but also Large Companies.

List of Websites:
Public website address: www.emfweld.com

EMFWELD software: www.emfweld.eu

Some other project related links:

- Release video (same video in the following link: http://youtu.be/oSPjV3PKXKk )
- Tutorial Videos (the tutorials can be found here: http://www.youtube.com/channel/UC8P3DcSDjRW7TcDGB_02btA )
- EMFWELD Tutorial – Webex (http://www.youtube.com/watch?v=P2ty8vhysXY&feature=youtu.be)

Project Coordinator - Eurico Assunção - egassuncao@isq.pt
Technical Coordinator - Geoff Melton - geoff.melton@twi.co.uk