A UK oil company was concerned about the number of ankle injuries suffered by staff wearing loose-fitting rigger boots on their exploration & production sites both onshore and offshore. The company investigated close-fitting lace-up boots as an alternative and identified three types which gave good ankle support. They then made it mandatory that staff and core contractors to their sites wear one of the selected types. However, although the new boots did help to reduce ankle injuries, staff wearing them reported some concerns about slips. The company therefore contracted the Health and Safety Laboratory (HSL) to study the slip resistance properties of their ‘approved’ footwear and to make recommendations on its suitability.
HSL tested four types of boot – types A, B, and C were on current issue and D was being considered for inclusion in the list. HSL utilised the HSL ramp test on three different floor surfaces using a continuous, pressurised water spray as the contaminant. They conducted grip tests on two regular site surfaces – gratings and scaffold boards - and compared them against the surface (sheet steel) used in the standard test.
All boots performed well on gratings and scaffold boards (although the materials were brand new and may not have been representative of the condition of these surfaces at site locations). However, boots A and D performed poorly when confronted with the ‘more challenging’ conditions of the standard test. Boot A also gave little grip feedback to the operators.
Boot C was reported as the most comfortable boot during the tests, and B was reported as being less comfortable at high ramp angles (i.e. when walking down a slope).
The company decided to remove boot A from their list and not to adopt D (with the current sole unit) into their range. This helped to relieve staff concerns about slips. They decided to keep B and C.
The company also decided to adopt the HSL standard test as the method of assessing grip capability of future footwear proposed for their ‘approved’ range. The acceptance criterion is that all footwear will perform above a minimum coefficient of friction of 0.24 (indicating moderate slip potential) in the standard test before being considered for their range. The company have charged their footwear supplier to challenge manufacturers to produce better footwear, which meets the new specification for grip and comfort, and they have responded by providing some new products for testing by HSL and subsequent trialling by staff.
This case study shows that footwear selection should not be based simply on one feature - ankle protection in this case - and that it is prudent to test the slip resistance of a range of footwear to assess how they meet all the necessary criteria, on surfaces likely to be encountered in the particular workplace.