STORAGE, HANDLING AND PROCESSING OF DANGEROUS SUBSTANCES - ELEMENT IC4

IC4.1 - Industrial chemical processes Unlike other branches of engineering (civil, mechanical, electrical, aerospace), which are concerned with mainly applied physics, chemical engineering is unique in integrating chemistry systematically into industrial chemical production. Most chemicals produced in industrial processes do not reach consumers, but are used as intermediates in manufacturing processes, such as bleaching agents in the textile and paper industries. Industrial processes fall into two main classes: inorganic and organic. Examples of inorganic include heavy chemicals such as acid or alkalis, which are consumed by industry in vast quantities. Organic includes fine chemicals such as dyes, pharmaceuticals and polymers, which are made from the raw material of hydrocarbons found in crude oil. Most plastics, resins, synthetic fibres, ammonia, methanol, and organic chemicals are manufactured from oil or natural gas. They are called petrochemicals, and there are hundreds of thousands of substances produced worldwide.

Factors affecting rate of chemical reaction A chemical reaction is a process that leads to the transformation of one set of chemical substances (reactants) to another (products) with different properties to the reactants. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, requiring some form of energy such as heat, light or electricity. Chemical reactions involve the movement of electrons in the breaking and forming of new chemical bonds; the rate of reaction can be affected by temperature, pressure and substances called catalysts. EFFECT OF TEMPERATURE The rate of reaction of any chemical process will increase with increases in the temperature of the reactants. The rate of reaction is exponential with temperature and increases by a factor of at least two for every 10oC rise. The reaction rate will also increase with increasing concentration of the reactant(s). For chemical reactions that are exothermic (generate heat energy) caution has to be taken to keep the reaction rate (which is exponential) within control, because the removal of heat, for example, by the use of cooling water, acts at a much slower transfer rate (linear process). Therefore it is essential to maintain the reaction temperature within a narrow band to prevent uncontrollable (run-away) conditions occurring. Consider a common organic polymerisation manufacturing process, involving the production of urea formaldehyde adhesive resins for the manufacture of chip-board. The process is relatively simple. Urea is mixed with 36% formaldehyde at a controlled pH and held for approximately 4 hours at 60oC. Polymerisation occurs and the viscosity of the material increases to a pre-determined value, which represents the increased molecular chain length required. If the temperature is not controlled carefully and is allowed to rise above 70oC, the exothermic reaction rate will become uncontrollable, resulting in high temperature, solidification of the reactants and release of volatile toxic materials, i.e. formaldehyde (WEL 2 ppm).

Reaction temperature control is a very important issue when considering scale-up processes from laboratory sized experiments (5 kg), increased through pilot plant (1,000 kg), to final production batch quantities (20,000 kg). The temperature control, particularly cooling, is far easier with small quantities of reactants than with increasing larger quantities, because the ratio of cooling surface decreases with increasing volume of reactants. See ‘Methods of control of temperature and pressure’ section later in this element. EFFECT OF PRESSURE The most significant use of pressure is the production of compressed gases, the most common being compressed oxygen, liquid nitrogen, and carbon dioxide produced from the fractional distillation of compressed air.

Figure IC4-1: Heat production/volume. Source: RMS.

Other gases are produced either directly or indirectly from chemical processes and for convenience are stored under pressure. Common gases are chlorine, liquefied petroleum gas (propane), sulphur dioxide, hydrogen, ammonia and acetylene. Some organic processes require reaction at relatively high pressure to prevent degradation of the products. One such reaction is the hydrogenation of castor oil in the manufacture of margarine. The reaction process is designed to be continuous and the reactants are combined at pressures of 200 atmospheres, which allows the products to be produced at much lower temperatures than at atmospheric pressure, below temperatures that would cause degradation.

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WORK EQUIPMENT (GENERAL) - ELEMENT IC5

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IC5.1 - Selection of suitable equipment Suitability of work equipment Work equipment includes:

Air compressor. Automatic car wash. Automatic storage and retrieval equipment. Blast furnace. Butcher's knife. Car ramp. Check-out machine. Combine harvester. Computer. Crane. Drill bit. Dry cleaning unit. Fire engine turntable. Hammer. Hand saw. Laboratory apparatus. Ladder. Lawn-mower. Lift truck. Lifting sling.

LPG filling plant. Mobile access platform. Overhead projector. Portable drill. Potato grading line. Power press. Pressure vessel. Quarry crushing plant. Resuscitator. Road tanker. Robot line. Scaffolding. Scalpel. Socket set. Soldering iron. Solvent degreasing bath. Tractor. Trench sheets. Vehicle hoist. X-ray baggage detector.

Not work equipment: Livestock. Substances. Structural items (buildings). Private car.

Suitability for the task, process and environment Every employer shall ensure that work equipment is so constructed or adapted as to be suitable for the

purpose for which it is used or provided. In selecting work equipment, every employer shall have regard to the working conditions and to the risks to

the health and safety of persons which exist in the premises or undertaking in which that work equipment is to be used and any additional risk posed by the use of that work equipment.

Every employer shall ensure that work equipment is used only for operations for which, and under conditions for which, it is suitable.

In this regulation "suitable" means suitable in any respect which it is reasonably foreseeable will affect the health or safety of any person.

Suitability of design and construction Intrinsic safety This is the condition where safety is established by ensuring selection and/or design of components and equipment that ensures no potential to cause harm. In practice this may actually be reduction of potential to an acceptable level. For example, the reduction in speed of rotation of a shaft does not eliminate it as a hazard but may reduce the risk such that it may be considered to be insignificant. By reducing the energy available to the component or equipment for example the reduction of force or electrical power required may cause the power or force to be below normal human thresholds of tolerance, thus preventing harm. Equipment must be suitable, by design, construction or adaptation, for the actual work it is provided to do. This should mean in practice that when employers provide equipment they should ensure that it has been produced for the work to be undertaken and that it is used in accordance with the manufacturer's specifications and instructions. If employers choose to adapt equipment then they must ensure that it is still suitable for its intended purpose. Designers should establish health and safety features that reduce risk at the design stage. Consideration should be given to all aspects of use. In addition, design should minimise risks at all phases of the life of the equipment including:

Construction. Transport. Installation. Commissioning.

De-commissioning. Dismantling. Disposal. Recycling.

WORK EQUIPMENT (WORKPLACE MACHINERY) - ELEMENT IC6

Quality system documentation. A written declaration that the application has not been submitted to another notified body.

The quality assurance system is approved by a notified body that has been accredited for this type of activity by UKAS and is subject to surveillance and audit by the notified body. The manufacturer is then able to issue relevant declaration documentation and affix CE marking. Where the full quality assurance procedure has been applied, the CE marking must be followed by the identification number of the notified body. USE OF HARMONISED STANDARDS Harmonised standards These are non-binding technical specifications adopted by one of the European Standard Organisations (CEN, CENELEC or ETSI) on the basis of a remit issued by the European Commission. These harmonised standards, that cover all the EHSRs, are published in the Official Journal of The European Communities. Where these standards have also been published as identically worded national standards ('transposed harmonised standards') and machinery is made in conformance to them they will be presumed to comply with the EHSRs covered by the European harmonised standards.

Figure IC6-7: Overview procedure for the machinery directive.

Source: Rockwell Automation.

The European Committee for Standardisation (CEN) and the European Committee for Electro-technical Standardisation (CENELEC) have been mandated to look at all existing machinery standards to ensure that where necessary they are revised to meet the requirements of the EU Machinery Directive 2006/42/EC. The European Commission periodically publishes in the Official Journal of The European Communities lists of standards that comply with the EU Machinery Directive 2006/42/EC [this list also may carry a note where a Standard has been found not to comply with one or more of the EHSRs]. The standards in support of the EU Machinery Directive 2006/42/EC are of three types. The first, A type, comprises general principles for the design of machinery. The second, B type, covers specific safety devices and ergonomic aspects of machinery. The third, C type, deals with specific classes of machinery by calling up the appropriate standards from the first two types and addressing requirements specific to the class. Only the latter can give a presumption of conformity with the EU Machinery Directive 2006/42/EC, because it defines criteria at a sufficiently detailed level.

Figure IC6-8: Planetary chart - A B and C standards. Source: RMS.

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WORKPLACE TRANSPORT AND DRIVING FOR WORK - ELEMENT IC10

IC10.1 - Hazards, risks and control measures for safe workplace transport operations

Typical hazards There are five main kinds of accidents associated with vehicles used in the workplace, which often result from loss of control of the vehicle, overturning vehicles, and collision with other vehicles, pedestrians and fixed objects. They form a significant part of the accidents that occur in workplace transport operations:

Being struck by a moving vehicle. Injury caused by a vehicle collapse or overturn. Falling from a vehicle. Being hit by a load (materials) falling from a vehicle. Being hit against a vehicle whilst travelling in it.

Many workers die each year because of works transport related accidents. There is also a high incidence of accidents causing serious injury, for example, spinal damage, amputation and crush injuries. Very few accidents involving traffic result in minor injury. In addition, transport accidents cause damage to plant, infrastructure and vehicles. LOSS OF CONTROL Hazards that can lead to loss of control of workplace vehicles include:

Slippery surfaces due to contamination of the surface by materials such as oil and dusts, leading to poor traction when steering or braking. Weather conditions such as ice and water can also affect control of the vehicle.

Potholes and other fracturing of the road surface, along with sudden changes of level, obstructions or kerbs. Contact with these may wrench the steering device from the hand of the driver or suddenly knock the steering in an unintended direction.

Overloading of vehicles, which can influence their manoeuvrability and braking performance. A counterbalance vehicle, such as a fork lift truck may be overloaded to such an extent that the steering wheels are not sufficiently in contact with the ground. The overloading of vehicles can cause the vehicle to require unusually long braking time or cause it to overbalance on cornering.

Excessive speed will also affect the performance of brakes and the ability of the driver to manoeuvre the vehicle, leading to loss of control.

Failure of one of the vehicle controls or critical items can lead to poor or loss of control of the vehicle. A sudden puncture in a pneumatic tyre could make the vehicle difficult to steer. If the conditions of brakes and steering deteriorate, they will perform badly and may cause the vehicle to move suddenly in an unintended direction.

OVERTURNING OF VEHICLES There are various circumstances that may cause a vehicle to overturn. They include: insecure and unstable loads, manoeuvring with the load elevated, colliding with kerbs and other obstructions, cornering at speed, braking harshly, driving on uneven or soft ground, and mechanical failure. Causes of vehicles overturning

Overloading or uneven loading of the bucket/forks. Driving with the load elevated. Driving too fast, cornering at excessive speed. Sudden braking. Hitting obstructions, buildings, structures or other

vehicles. Driving across slopes. Driving too close to the edges of slopes,

embankments or excavations. Driving over debris, holes in the ground, such as

drains.

Figure IC10-1: Vehicle overturned. Source: Lincsafe.

Mechanical defects that occur because of lack of maintenance. Inappropriate or unequal tyre pressures.

COLLISIONS WITH OTHER VEHICLES, PEDESTRIANS OR FIXED OBJECTS People may unexpectedly appear from a part of a building/structure or workers intent on the work they are doing may step away from where they are working to collect materials or tools. Through these actions they may step in front of vehicles and cause the driver to take emergency action.

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