The role of guarding in making paper safe
‘Making paper safely’ is a phrase that has been used within the papermaking industry since 1998, thanks to an initiative from the HSC (Health and Safety Commission) to improve the safety record of paper mills.
In November 2011, PABIAC launched phase 3 of its health and safety strategy for the paper industry. ‘Being the Difference Together’ builds on the industry’s previous achievements and establishes new targets for health and safety improvements during 2012 to 2014. The objectives contained within the strategy were agreed following industry consultation.
PABIAC includes representatives from the industry and unions, and it has published a set of six books called ‘‘Guide to managing health and safety in paper mills’ (ISBN 0 7176 2942 2, priced £25).
This guidance replaces the longstanding ‘Safety in paper mills’, more commonly known as the ‘Fourth Report’, and reflects technological progress. It is aimed at users of papermaking machinery to help them carry out risk assessments to compare
what they have now with the control, measures recommended and to decide what more they need to do (if anything). It applies to hazards arising from the papermaking process and gives advice, not only on guarding but also on such matters as housekeeping, safe access and systems of work.
Risk of serious injury
Two particular aspects of the papermaking industry give rise to concern: heavy rolls and fast-moving webs of paper mean that any injury carries a high probability of being serious or fatal. Furthermore, to keep mills running as efficiently as possible, operators have traditionally accessed hazardous parts of the machine to feed paper between the rolls at startup, to clean beneath the machine, and to clear blockages. So, despite the fact that the number of serious and fatal injuries in the papermaking industry has been falling in recent years, the HSE is keen to see further improvements.
There are examples of papermaking machinery in the UK that are, in some cases, almost 100 years old. Guarding on older machinery is certainly not up to today’s standards, and there is no such thing as a one-size-fits-all guard; each mill and each machine needs to be considered individually. Some machines currently have little or no physical guarding, while others are commonly fitted with lift-off guarding. However, such guards are no longer considered acceptable because they can too easily be removed while the machine is running, exposing the operator or maintenance technician to significant hazards.
Four main types of guarding are available and each must be used appropriately. But before any type of guarding is considered, a risk assessment needs to be carried out to establish what the hazards are, how frequently a person will be exposed to those hazards, and what the likelihood and severity of an injury would be. It is, of course, important that the risk assessment is documented.
The guarding options are, broadly-speaking, fixed guards, interlocked guards, electro-sensitive guards, and nip guards. Fixed guards can only be removed using a tool but, if at all possible, suitable access should be designed-in so that the guards will seldom have to be fully removed. Care also needs to be taken to ensure that people cannot access hazardous parts of the machine by reaching around or over fixed guards (or through, if guards use mesh or bars).
As a rule-of-thumb, if fixed guards need to be removed more than once per week – even for maintenance or cleaning – an interlocked guard should be considered instead. Interlocked guards will cause the machine to be stopped if the guards are opened; alternatively, the power to the machine must be removed before the guard can be opened. For low-risk applications, it is acceptable to use an interlock with a single actuator on the guard and a single control channel, but higher risk applications need two independent actuators with separate control channels so that, should one switch or channel fail, the other will operate as it should. For front face guarding on large reeler slitters and other very high-risk areas, the interlocking system should have dual control channels with cross-monitoring.
If part of a machine takes longer than ten seconds or so to come to rest, a time-delay relay should be incorporated so that the guard will remain locked until the machine has come to rest. Other high-risk situations, such as those where there is more than one entry point to the guarded area, might require a trapped key exchange interlock.
Electro-sensitive guards, such as light curtains and pressure-sensitive mats, can be suitable for some applications in the papermaking industry, but careful consideration needs to be given to the harsh operating conditions found in this industry and whether the more sophisticated – and often costly – devices are justified through marginally reduced access times.
Nip points are inherent in papermaking machinery, so nip guards should be considered if there is a risk of somebody gaining access to the nip. Several different designs of nip bars can be fitted, but the remaining gap should be as small as possible (and always less than 8mm), and round-section nip bars should not be used because they create their own new in-running nips.
Procter Machine Guarding
Procter Machine Guarding has been involved with guarding papermaking machinery for over 50 years and over recent years has been particularly active since the introduction of Making Paper Safely, with over a dozen installations completed in UK mills in the last 12 months. In most of the projects undertaken bespoke guarding has been designed to suit each part of the machine; any necessary interlocking has been supplied as well, but with the customer taking responsibility for the wiring and the safety circuit. Mills tend to have their own preferences for interlocking, but invariably robust products are chosen, and key exchange systems are popular when multiple entry points exist.
A typical mill will require a combination of fixed, removable and hinged or sliding guards, with infills of welded mesh or bars generally allowing good viewing of the process but without an onerous requirement for cleaning.
A common misconception about guarding paper mills is that the main issue is to keep operators away from the hazards. However, it is vital to ensure that the fully operational, cleaning and maintenance needs of the mill are considered. Guards that do not provide adequate access are often removed and not replaced, giving rise to a situation that is more hazardous than would be the case if proper safe access had been designed-in from the outset.
In Procter’s experience, it is highly desirable to involve the operators and maintenance staff in the specification process to ensure that the most appropriate guarding is chosen (while still providing the required safety). Procter Machine Guarding then undertakes all of the detailed design and manufacture, and can also provide an installation service. In one recent project, no less than 14 installation staff were engaged on a project to install guarding during an extremely limited Easter shutdown period.
To achieve a satisfactory end-result, guarding should ideally be considered within the overall context of safety. As well as the physical guarding, the mill needs to be sure that there is a suitable safety control system that can handle the inputs from the guard interlocks and any other measures such as hold-to-run controls and crawl-speed selectors. The guarding and control system must also be backed up by safe methods of working, training and, most of all, a culture of safety that discourages people from unsafe practices.
Procter Machine Guarding is in an ideal position to provide advice, thanks to its long history of supplying guarding to paper mills. For performing risk assessments in accordance with the requirements of BS EN ISO 12100, the company provides a FREE Risk Assessment Calculator.
To discuss any requirements for guarding paper mills, please contact Procter Machine Safety.