" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."

Sunday, 27 February 2011 06:35

Safety

Written by
Rate this item
(0 votes)

Mill Safety

Mills and calenders are used extensively throughout the rubber industry. Running nip accidents (getting caught in the rotating rolls) are major safety hazards during operation of these machines. In addition, there is a potential for accidents during repair and maintenance of these and other machines used in the rubber industry. This article discusses these safety hazards.

In 1973 in the United States, the National Joint Industrial Council for the Rubber Manufacturing Industry concluded that for in-running nip points, a safety device that depended on action of the operator could not be regarded as an effective method of preventing running nip accidents. This is especially true of mills in the rubber industry. Unfortunately, little has been done to force code changes. Currently there is only one safety device that does not require operator action to activate. The body bar is the only widely accepted automatic device that is an effective means of preventing mill accidents. However, even the body bar has limitations and cannot be used in all cases unless modifications are made to the equipment and work practice.

The problem of mill safety is not a simple one; there are several major issues involved:

  • mill height
  • the size of the operator
  • auxiliary equipment
  • the way the mill is worked
  • the tack or stickiness of the stock
  • stopping distance.

 

Mill height makes a difference as to where the operator works the mill. For mills less than
1.27 m high, where the height of the operator is greater than 1.68 m, there is a tendency to work too high on the mill or too close to the nip. This allows for a very short reaction time for the automatic safety to stop the mill.

The size of the operator also dictates how close the operator needs to get to the mill face to work the mill. Operators come in many different sizes, and often must operate the same mill. The majority of the time no adjustment is made to the mill safety devices.

Auxiliary equipment such as conveyors or loaders can often conflict with safety cables and ropes. Despite codes to the contrary, often the safety rope or cable is moved to allow for the operation of the auxiliary equipment. This can result in the operator working the mill with the safety cable behind the operator’s head.

While the height of the mill and the auxiliary equipment have a part in the way a mill is worked, there are other factors which enter into the picture. If there is no mixing roll below the mixer to distribute the rubber evenly on the mill, the operator will have to physically move the rubber from one side of the mill to the other by hand. The mixing and moving of the rubber exposes the operator to increased risk of strain or sprain injuries in addition to the hazard of the mill nip.

The tack or stickiness of the stock poses an additional hazard. If the rubber sticks to the mill roll and the operator has to pull it off the roll, a body bar becomes a safety hazard. Operators of mills with hot rubber have to wear gloves. Mill operators use knives. Tacky stock can grab a knife, glove or bare hand and pull it toward the running nip of the mill.

Even an automatic safety device will not be effective unless the mill can be stopped before the operator reaches the running nip of the mill. Stopping distances must be checked at least weekly and the brakes tested at the beginning of each shift. Dynamic electrical brakes must be checked on a regular basis. If the zero switch is not adjusted properly, the mill will move back and forth and damage to the mill will result. For some situations, disc brakes are preferred. With electrical brakes a problem can arise if the operator has activated the mill stop button and then tried an emergency mill stop. On some mills the emergency stop will not work after the mill stop button has been activated.

There have been some adjustments made that have improved mill safety. The following steps have greatly reduced exposure to running nip injuries on the mills:

  • A body bar should be used on the working face of each mill, but only if the bar is adjustable for the height and reach of the operator.
  • Mill brakes can be either mechanical or electrical, but they must be checked each shift and the distance checked weekly. The stopping distances should comply with the American National Standards Institute (ANSI) stopping distance recommendations.
  • Where mixer mills have hot, tacky stock, a two-mill system has replaced the single-mill system. This has reduced operator exposure and improved the mixing of the stock.
  • Where operators are required to move stock across a mill, a mixing roll should be added to reduce operator exposure.
  • Current mill work practices have been reviewed to insure that the operator is not working too close to the running nip on the mill. This includes small lab mills, especially where a sample may require numerous passes through the running nip.
  • Mill loaders have been added on mills to load stock. This has eliminated the practice of trying to load a mill using a fork truck, and has eliminated any conflict with the use of a body bar as a safety device.

 

Currently technology exists to improve mill safety. In Canada, for example, a rubber mill cannot be operated without a body bar on the working face or front of the mill. Countries receiving older equipment from other countries need to adjust the equipment to fit their workforce.

Calender Safety

Calenders have many configurations of machines and auxiliary equipment, making it difficult to be specific on calender safety. For a more in-depth study in calender safety, see National Joint Industrial Council for the Rubber Manufacturing Industry (1959, 1967).

Unfortunately, when a calender or any other piece of equipment has been transferred from one company to another or one country to another, often the accident history is not included. This has resulted in the removal of guards and in dangerous work practices that had been changed because of a prior incident. This has led to history repeating itself, with accidents that have occurred in the past reoccurring. Another problem is language. Machines with the controls and instructions in a different language from the user country makes safe operation more difficult.

Calenders have increased in speed. The braking ability of these machines has not always kept pace with the equipment. This is especially true around the calender rolls. If these rolls cannot be stopped in the recommended stopping distance, an additional method must be used to protect employees. If necessary, the calender should be equipped with a sensing device that will slow the machine when the rolls are approached during operation. This has proven very effective in keeping employees from getting too close to the rolls during the operation of the machine.

Some of the other major areas identified by the National Joint Industrial Council are still a source of injuries today:

  • clearing jams and adjusting material
  • running nip injuries, especially at wind-ups
  • threading up
  • communications.

 

An effective, well understood lockout programme (see below) will do much to reduce or eliminate injuries from the clearing of jams or the adjusting of material while the machine is in operation. Proximity devices that slow the rolls when they are approached may help deter an adjustment attempt.

Running nip injuries remain a problem, especially at wind-ups. Speeds at the wind-up must be adjustable to allow for a slow start-up at the beginning of the roll. Safeties must be available in the event of a problem. A device that slows the roll when it is approached will tend to discourage an attempt to adjust a liner or fabric during the wind-up. Telescoping rolls are a special temptation for even experienced operators.

The problem of threading-up incidents has increased with the speed and complexity of the calender train and the amount of auxiliary equipment. Here the existence of a single line control and good communications are essential. The operator may not be able to see all of the crew. Everyone must be accounted for and communications must be clear and easily understood.

The need for good communications is essential to safe operation when a crew is involved. Critical times are when adjustments are being made or when the machine is started at the beginning of a run or started after a shut-down which had been caused by a problem.

The answer to these problems is a well-trained crew that understands the problems of calender operation, a maintenance system that maintains all safety devices is working condition and a system that audits both.

Machine Lockout

The concept of machine lockout is not new. While lockout has been generally accepted in maintenance programmes, very little has been done to gain acceptance in the operating area. Part of the problem is the recognition of the hazard. A typical lockout standard requires that “if the unexpected movement of equipment or release of energy could cause injury to an employee then that equipment should be locked out”. Lockout is not limited to electrical energy, and not all energy can be locked out; some things must be blocked in position, pipes must be disconnected and blanked, stored pressure must be relieved. While the lockout concept is viewed in some industries as a way of life, other industries have not accepted it due to the fear of the cost of locking out.

Central to the concept of lockout is control. Where the person is at risk for injury as the result of movement, the power source(s) must be disabled and the person or persons at risk should have control. All situations requiring lockout are not easy to identify. Even when they are identified, it is not easy to change work practices.

Another key to a lockout programme which is often overlooked is the ease with which a machine or line can be locked out or the power isolated. Older equipment was not designed or installed with lockout in mind. Some machines were installed with a single breaker for several machines. Other machines have multiple power sources, making lockout more complicated. To add to this problem, motor control room breakers are often changed or feed additional equipment, and the documentation of the changes is not always kept current.

The rubber industry has seen general acceptance of lockout in maintenance. While the concept of protecting one’s self from the dangers of unexpected movement is not new, the uniform use of lockout is. In the past, maintenance personnel used different means to protect themselves. This protection was not always consistent due to other pressures such as production, and not always effective. For some of the equipment in the industry, the lockout answer is complex and not easily understood.

The tyre press is an example of a piece of equipment for which there is little consensus on the exact time and method for lockout. While the complete lockout of a press for an extensive repair is straightforward, there is no consensus about lockout in such operations as mould and bladder changes, mould cleaning and unjamming equipment.

The tyre machine is another example of difficulty in lockout compliance. Many of the injuries in this area have not been to maintenance personnel, but rather to operators and tyre technicians making adjustments, changing drums, loading or unloading stock or unjamming equipment and to janitorial employees cleaning the equipment.

It is difficult to have a successful lockout programme if the lockout is time consuming and difficult. Where possible, the means to disconnect should be available at the equipment, which helps with ease of identification and can eliminate or reduce the possibility of someone being in the danger zone when the energy is returned to the equipment. Even with changes that make identification easier, no lockout can ever be considered complete unless a test is made to be sure the correct power isolation devices were used. In the case of work with electrical wiring, a test should be made after the disconnect is pulled to ensure that all power has been disconnected.

An effective lockout programme must include the following:

  • The equipment should be designed to facilitate a lockout for all energy sources.
  • Lockout sources must be identified correctly.
  • Work practices requiring lockout must be identified.
  • All employees affected by lockout should have some training in lockout.
  • Employees who are required to lockout should be trained and advised that lockout is expected and that anything less is unacceptable under any circumstances.
  • The programme needs to be audited on a regular basis to make sure that it is effective.

 

Back

Read 4179 times Last modified on Tuesday, 28 June 2011 13:26

Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Chemical Processing
Oil and Natural Gas
Pharmaceutical Industry
Rubber Industry
Resources
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides

Rubber Industry Additional Resources

Click the Button below to view additional resources for this topic.

button

Rubber Industry References

American Conference of Governmental Industrial Hygienists (ACGIH). 1995. Industrial Ventilation: A Manual of Recommended Practice, 22nd ed. Cincinnati: OH: ACGIH.

Andjelkovich, D, JD Taulbee, and MJ Symons. 1976. Mortality experience in a cohort of rubber workers, 1964–1973. J Occup Med 18:386–394.

Andjelkovich, D, H Abdelghany, RM Mathew, and S Blum. 1988. Lung cancer case-control study in a rubber manufacturing plant. Am J Ind Med 14:559–574.

Arp, EW, PH Wolf, and H Checkoway. 1983. Lymphocytic leukemia and exposures to benzene and other solvents in the rubber industry. J Occup Med 25:598–602.

Bernardinelli, L, RD Marco, and C Tinelli. 1987. Cancer mortality in an Italian rubber factory. Br J Ind Med 44:187–191.

Blum, S, EW Arp, AH Smith, and HA Tyroler. 1979. Stomach cancer among rubber workers: An epidemiologic investigation. In Dusts and Disease. Park Forest, IL: SOEH, Pathotox Publishers.

Checkoway, H, AH Smith, AJ McMichael, FS Jones, RR Monson, and HA Tyroler. 1981. A case-control study of bladder cancer in the U.S. tire industry. Br J Ind Med 38:240–246.

Checkoway, H, T Wilcosky, P Wolf, and H Tyroler. 1984. An evaluation of the associations of leukemia and rubber industry solvent exposures. Am J Ind Med 5:239–249.

Delzell, E and RR Monson. 1981a. Mortality among rubber workers. III. Cause-specific mortality 1940–1978. J Occup Med 23:677–684.

—. 1981b. Mortality among rubber workers. IV. General mortality patterns. J Occup Med 23:850–856.

Delzell, E, D Andjelkovich, and HA Tyroler. 1982. A case-control study of employment experience and lung cancer among rubber workers. Am J Ind Med 3:393–404.

Delzell, E, N Sathiakumar, M Hovinga, M Macaluso, J Julian, R Larson, P Cole, and DCF Muir. 1996. A follow-up study of synthetic rubber workers. Toxicology 113:182–189.

Fajen, J, RA Lunsford, and DR Roberts. 1993. Industrial exposure to 1,3-butadiene in monomer, polymer and end-user industries. In Butadiene and Styrene: Assessment of Health Hazards, edited by M Sorsa, K Peltonen, H Vainio and K Hemminki. Lyon: IARC Scientific Publications.

Fine, LJ and JM Peters. 1976a. Respiratory morbidity in rubber workers. I. Prevalence of respiratory symptoms and disease in curing workers. Arch Environ Health 31:5–9.

—. 1976b. Respiratory morbidity in rubber workers. II. Pulmonary function in curing workers. Arch Environ Health 31:10–14.

—. 1976c. Studies of respiratory morbidity in rubber workers. III. Respiratory morbidity in processing workers. Arch Environ Health 31:136–140.

Fine, LJ, JM Peters, WA Burgess, and LJ DiBerardinis. 1976. Studies of respiratory morbidity in rubber workers. IV. Respiratory morbidity in talc workers. Arch Environ Health 31:195–200.

Fox, AJ and PF Collier. 1976. A survey of occupational cancer in the rubber and cablemaking industries: Analysis of deaths occurring in 1972–74. Br J Ind Med 33:249–264.

Fox, AJ, DC Lindars, and R Owen. 1974. A survey of occupational cancer in the rubber and cablemaking industries: Results of a five-year analysis, 1967–71. Br J Ind Med 31:140–151.

Gamble, JF and R Spirtas. 1976. Job classification and utilization of complete work histories in occupational epidemiology. J Occup Med 18:399–404.

Goldsmith, D, AH Smith, and AJ McMichael. 1980. A case-control study of prostate cancer within a cohort of rubber and tire workers. J Occup Med 22:533–541.

Granata, KP and WS Marras. 1993. An EMG-assisted model of loads on the lumbar spine during asymmetric trunk extensions. J Biomech 26:1429–1438.

Greek, BF. 1991. Rubber demand is expected to grow after 1991. C & EN (13 May): 37-54.

Gustavsson, P, C Hogstedt, and B Holmberg. 1986. Mortality and incidence of cancer among Swedish rubber workers. Scand J Work Environ Health 12:538–544.

International Agency for Research on Cancer (IARC). 1992. 1,3-Butadiene. In IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Occupational Exposures to Mists and Vapours from Strong Inorganic Acids and Other Industrial Chemicals. Lyon: IARC.

International Institute of Synthetic Rubber Producers. 1994. Worldwide Rubber Statistics. Houston, TX: International Institute of Synthetic Rubber Producers.

Kilpikari, I. 1982. Mortality among male rubber workers in Finland. Arch Environ Health 37:295–299.

Kilpikari, I, E Pukkala, M Lehtonen, and M Hakama. 1982. Cancer incidence among Finnish rubber workers. Int Arch Occup Environ Health 51:65–71.

Lednar, WM, HA Tyroler, AJ McMichael, and CM Shy. 1977. The occupational determinants of chronic disabling pulmonary disease in rubber workers. J Occup Med 19:263–268.

Marras, WS and CM Sommerich. 1991. A three dimensional motion model of loads on the lumbar spine, Part I: Model structure. Hum Factors 33:123–137.

Marras, WS, SA Lavender, S Leurgans, S Rajulu, WG Allread, F Fathallah, and SA Ferguson. 1993. The role of dynamic three dimensional trunk motion in occupationally-related low back disorders: The effects of workplace factors, trunk position and trunk motion characteristics on injury. Spine 18:617–628.

Marras, WS, SA Lavender, S Leurgans, F Fathallah, WG Allread, SA Ferguson, and S Rajulu. 1995. Biomechanical risk factors for occupationally related low back disorder risk. Ergonomics 35:377–410.

McMichael, AJ, DA Andjelkovich, and HA Tyroler. 1976. Cancer mortality among rubber workers: An epidemiologic study. Ann NY Acad Sci 271:125–137.

McMichael, AJ, R Spirtas, and LL Kupper. 1974. An epidemiologic study of mortality within a cohort of rubber workers, 1964–72. J Occup Med 16:458–464.

McMichael, AJ, R Spirtas, LL Kupper, and JF Gamble. 1975. Solvent exposures and leukemia among rubber workers: An epidemiologic study. J Occup Med 17:234–239.

McMichael, AJ, R Spirtas, JF Gamble, and PM Tousey. 1976a. Mortality among rubber workers: Relationship to specific jobs. J Occup Med 18:178–185.

McMichael, AJ, WS Gerber, JF Gamble, and WM Lednar. 1976b. Chronic respiratory symptoms and job type within the rubber industry. J Occup Med 18:611–617.

Monson, RR and KK Nakano. 1976a. Mortality among rubber workers. I. White male union employees in Akron, Ohio. Am J Epidemiol 103:284–296.

—. 1976b. Mortality among rubber workers. II. Other employees. Am J Epidemiol 103:297–303.

Monson, RR and LJ Fine. 1978. Cancer mortality and morbidity among rubber workers. J Natl Cancer Inst 61:1047–1053.

National Fire Protection Association (NFPA). 1995. Standard for Ovens and Furnaces. NFPA 86. Quincy, MA: NFPA.

National Joint Industrial Council for the Rubber Manufacturing Industry. 1959. Running Nip Accidents. London: National Joint Industrial Council for the Rubber Manufacturing Industry.

—.1967. Safe Working of Calenders. London: National Joint Industrial Council for the Rubber Manufacturing Industry.

Negri, E, G Piolatto, E Pira, A Decarli, J Kaldor, and C LaVecchia. 1989. Cancer mortality in a northern Italian cohort of rubber workers. Br J Ind Med 46:624–628.

Norseth, T, A Anderson, and J Giltvedt. 1983. Cancer incidence in the rubber industry in Norway. Scand J Work Environ Health 9:69–71.

Nutt, A. 1976. Measurement of some potentially hazardous materials in the atmosphere of rubber factories. Environ Health Persp 17:117–123.

Parkes, HG, CA Veys, JAH Waterhouse, and A Peters. 1982. Cancer mortality in the British rubber industry. Br J Ind Med 39:209–220.

Peters, JM, RR Monson, WA Burgess, and LJ Fine. 1976. Occupational disease in the rubber industry. Environ Health Persp 17:31–34.

Solionova, LG and VB Smulevich. 1991. Mortality and cancer incidence in a cohort of rubber workers in Moscow. Scand J Work Environ Health 19:96–101.

Sorahan, R, HG Parkes, CA Veys, and JAH Waterhouse. 1986. Cancer mortality in the British rubber industry 1946–80. Br J Ind Med 43:363–373.

Sorahan, R, HG Parkes, CA Veys, JAH Waterhouse, JK Straughan, and A Nutt. 1989. Mortality in the British rubber industry 1946–85. Br J Ind Med 46:1–11.

Szeszenia-Daborowaska, N, U Wilezynska, T Kaczmarek, and W Szymezak. 1991. Cancer mortality among male workers in the Polish rubber industry. Polish Journal of Occupational Medicine and Environmental Health 4:149–157.

Van Ert, MD, EW Arp, RL Harris, MJ Symons, and TM Williams. 1980. Worker exposures to chemical agents in the manufacture of rubber tires: Solvent vapor studies. Am Ind Hyg Assoc J 41:212–219.

Wang, HW, XJ You, YH Qu, WF Wang, DA Wang, YM Long, and JA Ni. 1984. Investigation of cancer epidemiology and study of carcinogenic agents in the Shanghai rubber industry. Cancer Res 44:3101–3105.

Weiland, SK, KA Mundt, U Keil, B Kraemer, T Birk, M Person, AM Bucher, K Straif, J Schumann, and L Chambless. 1996. Cancer mortality among workers in the German rubber industry. Occup Environ Med 53:289–298.

Williams, TM, RL Harris, EW Arp, MJ Symons, and MD Van Ert. 1980. Worker exposure to chemical agents in the manufacture of rubber tires and tubes: Particulates. Am Ind Hyg Assoc J 41:204–211.

Wolf, PH, D Andjelkovich, A Smith, and H Tyroler. 1981. A case-control study of leukemia in the U.S. rubber industry. J Occup Med 23:103–108.

Zhang, ZF, SZ Yu, WX Li, and BCK Choi. 1989. Smoking, occupational exposure to rubber and lung cancer. Br J Ind Med 46:12–15.