Machine Guarding Basics: Proper Guarding Reduces Exposure to Equipment Hazards

This article is based on a webinar by the Grain Handling Safety Coalition as part of the Stand Up for Grain Safety Week, March 25-29, 2019. The presenter was John Lee, director of safety, health, and environmental services at the Grain and Feed Association of Illinois, Springfield, (217-787-2417).

The equipment used in the grain industry is unforgiving and much of it is potentially hazardous. You must identify these potential hazards and guard against them.

Machine Guarding Basics

Proper guarding of equipment hazards reduces exposure to potential injury to workers from pinch points, nip points, wrap points, pull-in points, and cutting/shearing points.

Examples at grain facilities of machines with these hazards include pulleys, belts, gears, chains, power take-off (PTO), augers, motor drive shafts, drag and belt conveyors, V-belts, mower blades, grinders, and saws.

Types of Machine Guards

  • Fixed – If the guard is engineered correctly, it creates a barrier that is tool-tight and cannot be removed easily. It should be a permanent fixture and is the first choice to cover a hazard.
  • Interlocked – When open, the machine, such as a manlift, does not function. It’s not a substitute for lockout/tagout.
  • Adjustable – Protects users from blades, such as band or circular saws and grinders.
  • Other – Photoelectric, two-hand trip, pressure sensing, and physical barriers are among the alternatives.

Identify Hazards/Corrective Actions

With any machine guard, ask this question: Can any part of you go around, under, through, or over (AUTO)? If the answer is yes to any part of this question, the guard is insufficient (see p. 94).

Occupational Safety and Health Administration (OSHA) inspections in the early 2000s found that the No. 1 guarding issue was V-belts. Guards either weren’t installed, or if they were, the back wasn’t covered.

All guards should be six-sided: top, bottom, front, back, left, and right.

OSHA Standard 1910.217(o) addresses the distance between protective covering and moving parts of equipment. The farther from a hazard, the larger the hole can be on a protective expanded metal covering. If the distance is greater than seven feet, a protective covering is not required.

Do not use wing nuts to secure coverings. It’s not an OSHA standard, but a good rule of thumb is that the cover shouldn’t be something you can take off by hand. Some facilities use screws that require a special tool to remove.

Equipment Guarding

According to OSHA Standard 1910.219(c)(4)(i), a projecting shaft end protruding more than one-half the diameter of the shaft must be guarded by non-rotating caps or safety sleeves. Shafts with keyways can catch clothing easily.

Do not operate conveyors without covers. If a conveyor must run without a cover, use an expanded metal guard complying with the OSHA standard on openings.

Sump holes in bins must have grates/guards, whether you’re running an auger or not. Use jamb bolts to secure the grate, which must meet OSHA distance standards.

I have seen incidents involving stepping in a sump hole five times in my career, and four times the workers came up either missing part of their leg or their foot.

For PTO equipment, the rotating shaft needs to have a shield.

Angle grinders are the most dangerous tool in a workshop. Be sure guards are in place on tools and meet OSHA standards.

There is no grandfathering for machine guarding, either. Old c equipment must be guarded to the latest specifications.

Lockout/Tagout

When machine guarding must be removed for service or repairs, lockout/tagout is an important step and arguably the most important OSHA standard. So many accidents could be prevented by using it.

When performing lockout/tagout, control energy sources by de-energizing or isolating them to prevent unexpected startup. It’s not OSHA citations we’re worried about; it’s the people. That’s what guarding is about.

To view John Lee’s webinar at no charge, go to grainnet.com/machineguard or scan the QR code.

- John Reidy, associate editor

- From the November/December 2020 GRAIN JOURNAL