Revolution and Evolution
Published: 10th Nov 2011
Industrial footwear under scrutiny
Safety footwear is by far the most emotive of all personal protective products issued to workers as each individual is so different. In addition to personal taste, workers may have exceptional size requirements, alternative width requirements or they may need orthotic correction of some degree for them to achieve a comfort level to enable them to wear their footwear all day.
International testing standards
Currently there is no single accepted international safety standard for protective footwear, but many countries recognise the following standards to certain degrees. The European EN ISO 20345 (which is also recognised as a British Safety Standard in the United Kingdom), ASTM from the United States, CSA from Canada and SS513 from Singapore (which is identical in many ways to the EN standard), to name a few.
There is an increasing desire among manufacturers and distributors to move towards a single international standard. Not only would this reduce costs on manufacturers that work across continents, but it would also allow a far greater choice to end users, especially those in Europe who could benefit from ranges from the USA and Canada that offer many width fittings, as opposed to the current choice of a single width.
For the most part we will refer back to the European Standard; however, it will be necessary to include reference to the other international standards for comparison.
BS EN ISO 20345 was finalised in 2004 and superseded the previous standards of participating countries in 2005. It is the standard recognised by the following countries: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. There is more information on the various standards and standards’ organisations available on the Internet at the ASTM website: www.astm.org
• Canadian Standards Association (CSA): www.csa.ca • European Standard (EN): www.iso.org • Singapore Standard (SS): www.standards.org.sg • American National Standards Institute (ANSI): www.ansi.org • International Organization for Standardization (ISO): www.iso.ch • Occupational Safety and Health Administration (OSHA): www.osha.gov
Marking codes within EN ISO 20345
In addition to a safety shoe complying to EN ISO 20345 it will also be marked with a sub code or codes to convey its specific qualities to the user. For safety officers and specifiers, these codes are critical as not all safety shoes have the same performance characteristics. Sub codes within the standard are: EN ISO 20345: SB Toe protection with 200 Joules impact and 15kN compression force HRO Heat resistant outsole compound tested at 300° C P Penetration resistant outsole tested at 1100 newtons A Electrical resistance between foot and ground of between 0.1 and 1000 Mega Ohms C Electrical resistance between foot and ground of less than 0.1 Mega Ohms I Electrically insulating (refers to code II vulcanised/moulded footwear only) AN Ankle protection CR Cut resistant upper CI Insulation against cold HI Insulation against heat E Energy absorption of the seat area to 200 Joules WRU Water resistant upper leather* WR Water resistant footwear M Metatarsal protection In many cases a safety shoe will have more than one attribute from the above list, therefore the standard has designated the following combinations: S1 Footwear made from leather and other materials excluding all rubber or all polymeric (totally moulded footwear) footwear + closed seat region +SB + A + E S2 Footwear to S1 plus WRU S3 Footwear to S2 + P + cleated outsoles S4 All rubber (entirely vulcanised) or all Polymeric + SB + A + E S5 S4 + P + cleated outsoles *Styles that incorporate a waterproof breathable membrane will quite often be designated WRU, S2 or S3. Although they may well be liquid proof to S5 they simply cannot pass S5.
This lists the most popular combinations within industry although there are at least ten other combinations within the standard.
In addition to the physically protective elements to the safety shoes, the standard also recognises the need to protect from slips. There are three levels of conformity with A designation being the lower performing product and designation C being the highest performing product.
SRA Slip resistance on ceramic tile floor with sodium lauryl sulphate solution (SLS) SRB Slip resistance on steel floor with glycerol SRC Slip resistance on ceramic tile floor with SLS and on a steel floor with glycerol
The basic construction of safety footwear (referred to from this point as safety shoes, which includes safety boots) has not really changed in decades; however, in terms of the materials available to shoe makers there have been many innovations which have improved the performance, protection, comfort, fit and cost.
The parts of a safety shoe are mainly as follows:
• Upper – This is the main part of the shoe and is still generally manufactured from leather, although with the advent of hard wearing, high performance synthetic materials such as ballistic nylon and Cordura® there are many styles which feature no leather at all
• Tongue – This section, which can be either leather or synthetic, bridges the gap between the two lacing flaps. This can be designed as a ‘Bellows’ type tongue which ensures that water or rain is prevented from entering the shoe by bypassing the tongue. Indeed, if the shoe has a waterproof membrane such as Sympatex® or GoreTex® then the shoe will be waterproof even if submerged (obviously not to a depth over the tongue area)
• Collar – This is the cushioned top of the boot which fits around the ankle area
• Footbed – This is the (usually) removable insert within the shoe which affords a little more comfort to the wearer. Insoles are normally replaceable but can also be removed or replaced with a third party product designed to either give extra comfort, such as a gel insole, available on the high street, or by a mildly correcting insole to correct gait problems, e.g. orthotic insole
• Toe Cap – The safety toe cap can be manufactured from steel, aluminium or nowadays composite material or fibreglass. Non-metal toe caps are increasingly being specified as they are generally lighter and are thought not to rob heat from the wearer’s feet in cold conditions. Non-metal toe caps are generally larger than their metal counterparts, which means that there is more room in the shoe as a result
• Insole – This is the first layer of the sole construction and can be stitched, tacked or glued to the Upper. The insole can be made from card, or alternatively can be a synthetic anti-penetration layer. Insoles from welted styles will have the welt attached to it
• Midsole – Increasingly this is manufactured from steel or high performance synthetic material to achieve an anti-penetration layer. The Midsole is completed with a layer of material which is usually lightweight and capable of absorbing shock. One of the most popular materials is PU (Polyurethane)
• Heel – The design of the heel can vary from style to style from being barely noticeable to being a well defined heel that will be suitable for workers climbing ladders. EN ISO 20345 requires the?heel to incorporate a shock absorber to reduce stress and fatigue on workers. Where a style has a heel there is usually a supportive shank installed to support the wearer’s foot at the instep; shanks can be manufactured from steel or TPU
• Outsole – This is the layer of the sole that contacts the ground and has to be both hard wearing, slip resistant, heat resistant and additionally resistant to static electricity, oil and chemicals. Popular materials for the Outsole include rubber, Polyurethane and Thermoplastic Urethane (TPU). The tread design of the outsole will vary greatly between different styles depending on their intended environment
Safety shoe construction
Safety shoes can be constructed in a number of different ways, which will depend on the materials being utilised within the shoe. Some construction methods have changed little in more than a century, while new materials have enabled manufacturers to develop new methods which have improved performance, comfort and price. The construction methods below are some of the most popular, but some less common ones have been omitted. • Welted construction – Is an old construction method sometimes referred to as ‘Goodyear Welted Construction’; this is where the upper is stitched to the insole and the ‘welt’, which is a strip visible on the outside of the shoe, above the outsole. The void between the insole and outsole is filled with a shock absorbing material (such as cork) and then finally the heavy duty rubber outsole is stitched and glued to the insole and the welt. Welted construction shoes can be re-soled later in their service life.
Welted shoes are also constructed on a ‘last’, which leads to a better fitting and far more comfortable pair of shoes than non-lasted shoes. Given that welted shoes are by nature classed as heavy duty, they are favoured by the construction industry where support and protection are the main features required. • Direct attach construction – This is a fairly new method of construction and requires fewer processes and materials to produce finished safety shoes. With this method the upper is usually placed on a last and the insole is stitched or tacked to the upper. The whole lasted unit is then placed in a mould, to which is added liquid polyurethane which fuses directly to the upper, automatically filling any voids and achieving a water tight bond.
This is usually a single part process, but with some styles can be a two part process if a dual density sole unit is required (usually a softer lighter midsole with a harder, heavier outsole). This method can be used to produce both safety shoes and safety boots, but this method cannot be re-soled. • Cement construction – This is a simple and cost effective method of safety shoe construction. Insoles and outsoles are simply glued together for an extremely lightweight and flexible shoe. This construction can be used to produce both safety shoes and safety boots but this method cannot be re-soled. • Opanka construction – Is an expensive, hand sewn construction of the outsole, insole and sock lining together which results in the most flexible and lightweight safety shoes available. This construction is predominantly used to produce safety shoes rather than safety boots. It is also unlikely that the wearer would have these re-soled.
Selection of safety footwear
Given the varied design, construction and differing materials used in manufacturing safety shoes, safety officers and specifiers of safety shoes face a seemingly daunting task to set the standards for their work environments.
Large sites with many workers carrying out a wide range of tasks will no doubt have need of most of the different constructions and materials mentioned in this article, while individual teams and small businesses could well function with a single style. It goes without saying, though, that the ultimate selection of safety footwear can only be made subject to a suitable and sufficient risk assessment having been carried out in relation to the hazards encountered in the workplace.
Once you have settled on a specification for your particular area or application, there can still be a large choice of conforming styles varying in price, features and comfort. This can often be the toughest part of the selection process, as workers will inevitably want the best styles which are usually the most expensive, while the employer will be keen to balance this with a less expensive but no less conforming style.
Many businesses seem to be settling on S3 as a minimum requirement for their workers, which will certainly provide them with a good starting point and ensure that they avoid many lower quality styles which do not reach this standard. Indeed, at the lower end of quality and price there is a risk of encountering styles which do not conform to EN ISO 20345 and are considered to be counterfeit.
From a UK perspective there are most certainly companies importing safety footwear which simply does not conform to the relevant standards, but the footwear is finding its way in to the marketplace with potentially dangerous results.
In some cases it is due to wilful flouting of the legal obligations of an importer, and in other cases it is simply down to ignorance and/or over confidence in the foreign manufacturer being able to produce safety shoes reliably enough to conform to the standard.
Over the past year the British Safety Industry Federation has instigated the ‘Registered Supplier Scheme’, which aims to provide end user companies with a register of audited distributors of safety equipment. The scheme recognises both manufacturers and bona fide distributors over and above simple re-sellers of safety products that may not possess any expertise in the industry, which could be viewed as potentially dangerous.
Distributors registered by the BSIF are audited to ensure that their businesses are managed correctly, that their staff are trained to industry standards and that they have a full understanding of the products that they distribute, including possession of EC testing and declarations of conformity.
In the author’s opinion, the future of safety footwear lies with innovation. Manmade fabrics and materials will increasingly be used to provide lighter, more flexible and more comfortable shoes. Fabrics such as Cordura® and ballistic nylon are already being used to create hard wearing footwear for industries where leather traditionally struggles to perform. Composite materials and aramid fabrics such as Kevlar® are likely to be chosen over steel and aluminium to provide the same level of protection, but with more flexibility with less weight.
Lacing and closure systems are also being improved upon. Low-tech slip on boots are being replaced with innovative closure systems, utilising side zips in addition to standard laces which enable quick donning and doffing. The new Boa® speed lace system found in a relatively small number of safety shoes now claims that the traditional lace is obsolete. This new lacing system works on a single push and pull button, with the lacing being tightened via the button to provide an even pressure across the whole of the lace, giving a high degree of comfort.
The recent cold winters have also seen manufacturers incorporate ice grips within a standard design that can be deployed in seconds, without the need to fit ugly, third party strap on solutions.
The last ten to 15 years have seen a great change in the safety footwear industry. For the most part this is due to the relocation of manufacturing through
Europe and finally to Asia. End users have enjoyed not only price stability, but on the whole, price reductions in real terms along with a revolution in designs available.
The sheer amount of choice available to end users is staggering, especially in the mid to high price ranges. The recent bi-annual A+A exhibition at Düsseldorf listed more than 200 safety footwear manufacturers.
The fundamentals, though, still apply as always. In order to ensure a reliable supply of safety footwear that provides value to your business, while covering all of the needs of the wearers and specifiers, it is important to engage with a distribution company that not only has expertise in the industry, but is also recognised by the industry it works in.
Published: 10th Nov 2011 in Health and Safety International