January 2009
Examiners’ Report NEBOSH International Diploma in Occupational Health and Safety (Unit IC)
Examiners’ Report NEBOSH INTERNATIONAL DIPLOMA IN OCCUPATIONAL HEALTH AND SAFETY Unit IC – International workplace and work equipment safety JANUARY 2009
CONTENTS
Introduction
2
General comments
3
Comments on individual questions
4
© 2009 NEBOSH, Dominus Way, Meridian Business Park, Leicester LE19 1QW tel: 0116 263 4700
fax: 0116 282 4000
email:
[email protected]
website: www.nebosh.org.uk
The National Examination Board in Occupational Safety and Health is a registered charity, number 1010444 T(s):exrpts/J/J-C0901
EXTERNAL
DW/DA/REW
Introduction
NEBOSH (The National Examination Board in Occupational Safety and Health) was formed in 1979 as an independent examining board and awarding body with charitable status. We offer a comprehensive range of globally-recognised, vocationally-related qualifications designed to meet the health, safety, environmental and risk management needs of all places of work in both the private and public sectors. Courses leading to NEBOSH qualifications attract over 25,000 candidates annually and are offered by over 400 course providers in 65 countries around the world. Our qualifications are recognised by the relevant professional membership bodies including the Institution of Occupational Safety and Health (IOSH) and the International Institute of Risk and Safety Management (IIRSM). NEBOSH is an awarding body recognised and regulated by the UK regulatory authorities: • • •
The Office of the Qualifications and Examinations Regulator (Ofqual) in England The Department for Children, Education, Lifelong Learning and Skills (DCELLS) in Wales The Council for the Curriculum, Examinations and Assessment (CCEA) in Northern Ireland
NEBOSH follows the “GCSE, GCE, VCE, GNVQ and AEA Code of Practice 2007/8” published by the regulatory authorities in relation to examination setting and marking (available at the Ofqual website www.ofqual.gov.uk). While not obliged to adhere to this code, NEBOSH regards it as best practice to do so. Candidates’ scripts are marked by a team of Examiners appointed by NEBOSH on the basis of their qualifications and experience. The standard of the qualification is determined by NEBOSH, which is overseen by the NEBOSH Council comprising nominees from, amongst others, the Health and Safety Executive (HSE), the Department for Education and Skills (Df ES), the Confederation of British Industry (CBI), the Trades Union Congress (TUC) and the Institution of Occupational Safety and Health (IOSH). Representatives of course providers, from both the public and private sectors, are elected to the NEBOSH Council. This report on the Examination provides information on the performance of candidates which it is hoped will be useful to candidates and tutors in preparation for future examinations. It is intended to be constructive and informative and to promote better understanding of the syllabus content and the application of assessment criteria. © NEBOSH 2009
Any enquiries about this report publication should be addressed to: NEBOSH Dominus Way Meridian Business Park Leicester LE10 1QW Tel: 0116 263 4700 Fax: 0116 282 4000 Email:
[email protected]
2
EXTERNAL
General comments
Many candidates are well prepared for this unit assessment and provide comprehensive and relevant answers in response to the demands of the question paper. This includes the ability to demonstrate understanding of knowledge by applying it to workplace situations. There are always some candidates, however, who appear to be unprepared for the unit assessment and who show both a lack of knowledge of the syllabus content and a lack of understanding of how key concepts should be applied to workplace situations. In order to meet the pass standard for this assessment, acquisition of knowledge and understanding across the syllabus are prerequisites. However, candidates need to demonstrate their knowledge and understanding in answering the questions set. Referral of candidates in this unit is invariably because they are unable to write a full, well-informed answer to one or more of the questions asked. Some candidates find it difficult to relate their learning to the questions and as a result offer responses reliant on recalled knowledge and conjecture and fail to demonstrate a sufficient degree of understanding. Candidates should prepare themselves for this vocational examination by ensuring their understanding, not rote-learning pre-prepared answers. Recurrent Problems It is recognised that many candidates are well prepared for their assessments. However, recurrent issues, as outlined below, continue to prevent some candidates reaching their full potential in the assessment. −
Many candidates fail to apply the basic principles of examination technique and for some candidates this means the difference between a pass and a referral.
−
In some instances, candidates are failing because they do not attempt all the required questions or are failing to provide complete answers. Candidates are advised to always attempt an answer to a compulsory question, even when the mind goes blank. Applying basic health and safety management principles can generate credit-worthy points.
−
Some candidates fail to answer the question set and instead provide information that may be relevant to the topic but is irrelevant to the question and cannot therefore be awarded marks.
−
Many candidates fail to apply the command words (also known as action verbs, eg describe, outline, etc). Command words are the instructions that guide the candidate on the depth of answer required. If, for instance, a question asks the candidate to ‘describe’ something, then few marks will be awarded to an answer that is an outline.
−
Some candidates fail to separate their answers into the different sub-sections of the questions. These candidates could gain marks for the different sections if they clearly indicated which part of the question they were answering (by using the numbering from the question in their answer, for example). Structuring their answers to address the different parts of the question can also help in logically drawing out the points to be made in response.
−
Candidates need to plan their time effectively. Some candidates fail to make good use of their time and give excessive detail in some answers leaving insufficient time to address all of the questions.
−
Candidates should also be aware that Examiners cannot award marks if handwriting is illegible.
3
EXTERNAL
UNIT IC – International workplace and work equipment safety
Section A – all questions compulsory
Question 1
A contractor is to repair the felt roofs of an office. Outline the measures that should be taken to reduce the risks to workers and members of the public.
(10)
This question required candidates to outline the practical measures that should be taken to protect both employees and members of the public whilst the contractor’s repair work was in progress. Selection and subsequent monitoring of the contractor is an important factor as are the completion of risk assessments and the development of safe systems of work and a method statement. Candidates, however, were expected to add to these general points and outline the more specific measures required in this scenario, such as the provision of appropriate means of access, the correct use of ladders, ensuring they were tied and footed, and the provision of edge protection or other means to prevent falls of persons and materials. Safe means of transporting tools and materials to and from the roof including enclosed debris chutes, the removal of waste from the site, precautions when using LPG and the use of trained and competent employees, provided with appropriate personal protective equipment such as gloves, boots, knee pads and masks are also crucial. Consideration should also be given to the possibility of contact with hazardous substances such as tar or asbestos and precautions taken to prevent exposure both of the contractor’s staff and members of the public. Additional measures to improve the health and safety of the office staff and members of the public include the erection of barriers and signs at ground level, safe arrangements for vehicle movement and security measures to prevent access to the site by unauthorised persons.
4
EXTERNAL
Question 2
A four-storey general hospital is to be refurbished and upgraded on a floor by floor basis, with three floors of the hospital remaining operational at all times. Outline the factors to be considered when writing fire evacuation procedures for the parts of the hospital that remain operational during the project.
(10)
In writing fire evacuation procedures for the hospital, factors to be considered include: the various activities involved such as wards, theatres, offices, outpatients and visitors; the number of patients and staff to be evacuated; the mobility of the patients including their medical condition and age; reviewing current and normal evacuation procedures including escape routes, assembly points and fire brigade access and identifying temporary procedures and routes such as the availability of operational lifts for bed-ridden patients; consideration of a two stage evacuation procedure; the provision of training to hospital and construction staff in the temporary arrangements; ensuring that escape routes and assembly points are kept clear of construction materials; the provision of emergency lighting and signage; considering the possibility of emergency zoning and classification for example for full or partial evacuation; assessing the effect of construction work on the existing detection, alarm and firefighting systems and on the possibility that it might increase the risk of fire; and assessing the need for first aid fire fighting provision and fire protection.
Question 3
A catastrophic fire occurs in a warehouse which stores a substance which gives off toxic products. The warehouse has an integral asbestos roof and it is situated near to a densely populated area. The fire burns for a day and completely destroys the building. (a)
(b)
Identify the environmental impacts related to this event, giving a probable source of EACH.
(5)
Identify the range of design features that could prevent or mitigate the environmental impacts of such an event at these premises.
(5)
In answering the first part of the question, candidates should have identified that the initial impact of the fire on the environment would be the release to atmosphere of greenhouse gases (including, eg carbon dioxide, methane and ozone), smoke and particulates such as soot. Additionally, asbestos fibres could be carried by air and contaminate the locality. There would also be the possibility that toxic products could enter sewers and water courses and also soak into the soil causing a detrimental effect on flora and fauna. Unless precautions were taken, fire fighting media could run off to watercourses whilst in the clean-up after the fire, waste products and sludge could be deposited in landfill sites. For part (b), design features that could have prevented or mitigated the impact on the environment include the initial construction of the building with non-combustible materials and introducing compartmentalisation; using a roofing material other than asbestos; providing protective fireproof coatings on steelwork; using impervious material in the construction of the floor; providing a flameproof storage container for the critical toxic substances; installing a fixed fire detection and protection system; fitting interceptors to the drains; constructing a bund round the warehouse; using fire water catch tanks or lagoons during the fire fighting operation and treating residual solids before consigning them to landfill sites.
5
EXTERNAL
Question 4
Outline the practical control measures that can be taken to minimise risk when operating a bench-mounted circular saw.
(10)
This question was concerned with the application of machinery safety principles to a specific item of work equipment. Good answers included reference to the need for the correct operation and/or adjustment of the top guard; the effective guarding of the blade beneath the bench; the use of a push stick to feed through the material being sawn and extending the machine table where persons are employed to remove the material whilst the machine was in motion; the correct positioning of the riving knife and the correct selection, maintenance and adjustment of the blade. Other measures that could have been outlined related to the training and competence of the operators; the provision of a local exhaust ventilation system; the provision and use of personal protective equipment such as goggles and hearing protection; the provision of sufficient space around the machine which should be kept free from obstruction; the provision of an emergency stop device and means of isolation; ensuring good standards of lighting, heating and ventilation; ensuring the stability of the machine and introducing procedures to ensure the regular maintenance of the machine and that guards were always in position.
Question 5
Legislation relating to lifting operations and lifting equipment often specifies fixed intervals between thorough examinations of lifting equipment but also includes an option for thorough examination to be carried out in accordance with an ‘examination scheme’. Outline the factors that a competent person would need to take into account when deciding whether less frequent examinations might be justified.
(10)
In answering this question, Examiners were looking to candidates to outline factors which the competent person would need to take into account such as the age of the equipment and its history including the extent of use, the loads lifted and the environments in which it has been used and its current and anticipated future use. Other factors which should also be considered include: the standards and specifications to which the equipment had been designed and manufactured and the quality conformance of materials at the time of manufacture; the manufacturers’ recommendations on testing, inspection and maintenance and whether they have been adhered to (by reference to records); the equipment’s accident, breakdown and repair history; records of modifications and the fitting of replacement parts; the records of previous thorough examinations; the typical performance history of similar items of equipment and any insurance company requirements.
6
EXTERNAL
Question 6
Unless appropriate precautions are taken, chemical reactions in a batch manufacturing process can give rise to conditions which can lead to a ‘runaway reaction’. (a)
Describe what is meant by ‘runaway reaction’.
(2)
(b)
Identify the conditions that may give rise to such an event.
(4)
(c)
Outline the design and operational features of chemical processes that are necessary to prevent such an event.
(4)
Candidates could have described “runaway reaction” as: an uncontrolled exothermic reaction where the heat produced exceeds the heat removed. The surplus heat raises the temperature of the reaction mass and hence the reaction rate resulting in a runaway reaction. Reference could also have been made to the fact that the rate of heat production is exponential whereas the rate of heat removal is linear. Candidates could then have gone on for part (b) to identify conditions such as: the presence of a strongly exothermic reaction; inadequate provision of, or failure in cooling of the reaction; the presence of contaminant catalysis; excessive quantities of reactants present in the reactor; the lack of sensitive temperature detection and control; the insulation of the reaction vessel where solid residues have built up on the internal walls of the vessel and mixer failure with loss of agitation. For part (c), carrying out a hazard and operability study (HAZOP) on the reaction process would be appropriate in this scenario. This might then lead to the inclusion of design features such as: high integrity temperature detection being linked to the cooling/reactant addition system; pressure rise detection linked to cooling, venting or auto shut-down; the protection of the vessel by correctly sized bursting discs; and the fitting of an agitation failure alarm. Candidates could have outlined operational features such as ensuring that: only a high calibre of operator was employed in such processes; that decision making requirements by operators in response to adverse operating conditions were minimised; that maintenance and/or raw material handling do not introduce potential catalysts into the reaction; that the rate of addition of reactants was limited and that inappropriate scale-up or fouling was avoided.
7
EXTERNAL
Section B – three from five questions to be attempted
Question 7
A rectangular warehouse building (40m x 100m ground area and 18m high) was constructed on a structural steel framework, with a flat roof and coated steel walls. During a storm, the warehouse suffered a catastrophic failure of one of its long walls which in turn caused the collapse of the roof and buckling of the other walls. (a)
Outline the possible causes of this structural failure.
(10)
(b)
Outline the health and safety issues to be considered when planning the subsequent demolition of the damaged warehouse.
(10)
Possible mechanisms of structural failure that could have been outlined in answering part (a) of this question included: impact damage by moving plant creating initial weakness; adverse weather conditions where the designed wind loadings were exceeded or low temperature resulting in brittle failure; overloading of the structure by excess weight on the roof caused by snow or rain water; weakening of the steelwork by corrosion through roof leaks or the in-operation of rain water drains; alteration to structural members which had invalidated the original design calculations; subsidence or nearby excavation or tunnelling operations creating instability and vibration caused by the volume of passing traffic or wind variation which would result in fatigue. For part (b), issues that should have been outlined were the competence of the demolition contractor; the method to be used for demolishing the partially collapsed structure to prevent premature collapse of the remainder and the preparation of a method statement to indicate the systematic approach that would be taken; precautions to be taken to prevent falls of people or material; the identification and isolation of buried services such as electricity, water and gas; the inspection, examination and maintenance of plant and equipment to be used; issues associated with manual handling and the use of mechanical equipment where this was possible; procedures for the removal of waste including categorised waste and the contents of the warehouse; identification of the possible presence of asbestos or lead paint; protection of adjoining property; the provision of appropriate personal protective equipment for the employees such as hard hats, boots and eye protection; the protection of the public including the erection of barriers and the introduction of arrangements to ensure site security; contaminated land issues and the need to introduce pest control.
8
EXTERNAL
Question 8
A pressurised steam boiler requires an examination; at the same time a repair on an electrically driven pump, associated with the boiler, is needed. (a)
(b)
(c)
Define the term ‘relevant fluid’ in relation to pressure systems safety.
(4)
Outline the typical contents of a written scheme of examination form for the boiler.
(8)
Identify the practical measures that should be taken to carry out the pump repair safely.
(8)
A “relevant fluid” means steam; any fluid or mixture of fluids which is at a pressure greater than 0.5 bar above atmospheric pressure and which fluid or mixture of fluids is a gas, or a liquid having a vapour pressure greater than 0.5 bar above atmospheric pressure when in equilibrium with its vapour at either the actual temperature of the liquid or at 17.5°C; or a gas dissolved under pressure in a solvent contained in a porous substance at ambient temperature and which could be released from the solvent without the application of heat. In their outline of the typical contents of a written scheme of examination form for the inspection of a boiler, candidates were expected to refer to items such as: the identification of the items of plant or equipment within the system; the parts of the system which are to be examined; the nature of the examination required including the inspection and testing to be carried out on protective devices; the preparatory work needed for the item to be examined safely; the maximum interval between examinations; whether an imminent danger report is required to be given to the enforcing authority and/or the employer; the critical parts of the system – if modified or repaired – which must be examined by a competent person before the system is used again; the name of the competent person certifying the written scheme and the date of certification. For part (c), candidates should have initially identified the need to issue a permit to work which would specify the control measures to be taken such as: the isolation and locking off of the electrical power to the pump; the isolation of pipelines by locking valves or inserting blanks; releasing stored energy, de-pressurising, draining and decontaminating the pump; allowing hot machinery to cool to at least 50ºC; segregating the work by the use of barriers and signs and providing safe means of access for employees who were to carry out the repair work. Other measures that should be taken include the use of skilled and competent personnel to carry out the work; the provision and use of personal protective equipment such as head protection, eye protection and gloves; the provision of a good standard of lighting and ventilation and finally ensuring co-ordination with the person conducting the examination of the boiler.
9
EXTERNAL
Question 9
Small electroplating companies often have poor standards of health and safety, made worse by the presence of conductive and corrosive fluids, and humid corrosive atmospheres. (a) (b)
Describe the types of fault that may be found in fixed electrical systems under such conditions.
(10)
Outline the information relating to fixed electrical systems that will be required prior to a survey by a competent person.
(10)
The first part of this question sought to examine candidates’ knowledge of typical faults within an electrical system and how a corrosive atmosphere may exacerbate the problems. Issues that should have been described included poor earthing, damaged sockets and switchgear, covers missing from junction boxes, incompetent workmanship and inadequate excess current protection. Additional problems caused by the atmosphere include exposed live conductors due to damaged or perished insulation; short circuits caused by the ingress of fluids; corrosion of system parts such as access grilles and transformer casings; and the unsuitability of the equipment for use in such wet and corrosive conditions. For part (b), the type of information required by a competent electrician prior to carrying out a survey would include: the type of equipment and its rating (eg operating voltage and current); its IP classification (including the measure of protection against the ingress of water); any circuit diagrams and/or manuals for the equipment and details of any modifications made; means of isolation and its location; earthing arrangements; the type and size of cables; details on the operation of protective devices and copies of previous inspection reports.
Question 10
(a) (b)
Outline the possible health and safety effects of inadequate workplace lighting.
(4)
Outline the factors that should be considered to ensure that lighting in a workplace is suitable and sufficient.
(16)
Better answers were able to identify the effects of inadequate lighting as those relating to health and those relating to safety. Health effects may include headaches, visual fatigue or eye strain and blurred vision and the effects of adopting a poor posture, such as neck and backache in order to have an adequate view of the task being performed. Safety implications include the likelihood of an increase in accidents due to trips, falls and striking against objects because the hazards are not identified, because of the use of the wrong type of lighting such as those producing a stroboscopic effect and through human error in performing a task which may put others at risk. For part (b), the factors to be considered in providing suitable and sufficient lighting include amongst others: the type of work to be undertaken, the amount of precision required and whether the tasks require general, local and/or localised lighting; the workplace layout giving attention to the effects of screens, furniture or racking and the shadows that might be cast; the levels of lighting in adjacent areas in order to avoid the effects of moving from a strongly lit area to one which is dimly lit and vice versa; the different types and levels of lighting required for stairs, corridors and outside security lights; the level of natural light available; the individual needs of the employees whether on account of age or disability; the possibility of glare on display screens and through reflection from other surfaces such as wall surfaces; the colour and types of lighting fitted to prevent stroboscopic effects; the need for emergency lighting particularly for fire escape routes; the need for portable lighting when work has to be carried out in confined spaces and the ease of maintenance whether replacing spent bulbs or cleaning the light fittings.
10
EXTERNAL
Question 11
In relation to dust explosions: (a)
(b)
(c)
(d)
explain the conditions that must be present for a primary dust explosion to occur;
(4)
explain the additional conditions necessary for secondary explosions to occur;
(4)
identify FOUR factors that may affect the reliability of a nitrogen inerting system used in a powdered aluminium process;
(4)
identify the design features that would minimise the likelihood and effect of a dust explosion.
(8)
In order for a primary dust explosion to occur, the dust must be combustible, must be capable of becoming airborne and mixing with air and its particle size and distribution must be capable of propagating flame. Additionally the concentration of dust must fall within the explosive limits, an ignition source of sufficient heat energy must come in contact with the dust and the atmosphere must contain sufficient oxygen to sustain combustion. Additional conditions necessary for secondary explosions to occur include the dislodgement of accumulated dust from horizontal surfaces within the affected building by the pressure wave and consequent air turbulence created by the primary explosion and the airborne suspension of combustible dust throughout the affected area which is ignited by the original primary explosion ignition source or by the combustion of products from the primary explosion or by any other ignition source with sufficient heat energy within the affected area. In answering part (c), candidates could have identified factors such as the number and location of sampling points; the type and calibration of the sensors; the presence of contaminants in the system which could interfere with readings; inadequate provision of a safe means of shutdown if oxygen levels are too high; the adequacy of the supply of inerting gas; the number of locations where air can enter the plant or process and the reliability of the electronic control system. In identifying design features that would minimise the likelihood and effect of a dust explosion, candidates should have referred to; the initial design of the ducting and equipment to withstand the effects of an explosion; the importance of ensuring the ducting was dust tight; providing local exhaust ventilation at points of transfer; installing explosion relief or suppression systems together with systems for suppressing fire; using screw conveyors instead of pneumatic systems for moving materials; providing a magnetic extraction system for removing metal from product fed to the plant; interlocking equipment to prevent overfilling of vessels and overpressurisation; using instrument systems with integral emergency shutdown; using intrinsically safe electrical equipment and bonding all metal work to earth; preventing dust build up in the plant by the use of sloping surfaces and introducing a mechanised system for the humidification of the air.
11
EXTERNAL
The National Examination Board in Occupational Safety and Health Dominus Way Meridian Business Park Leicester LE19 1QW telephone +44 (0)116 2634700 fax +44 (0)116 2824000 email
[email protected] www.nebosh.org.uk
