Abrasive wheel safety requirements

The maximum angular exposure for floor stand and bench-mounted wheels used for external grinding is 90 degrees, except it may be up to 125 degrees when work requires contact below the horizontal plane of the spindle; in both cases the exposure must begin no more than 65 degrees above the horizontal plane of the spindle. Requirement in 1915.134(a) requires the guard to also be strong enough to withstand the effect of a bursting wheel.

• The 90° limit is the normal maximum angular exposure of wheel periphery and sides for external grinding.
• The 125° limit is an exception strictly limited to operations that require contacting the wheel below the horizontal spindle plane; the exposure must still start within 65° above horizontal.

(See 1915.134(a).)

Work rests on floor and bench grinders must be rigidly supported, readily adjustable, and kept within 1/8 inch of the wheel surface. Requirement in 1915.134(b) specifies these controls to prevent the workpiece from being jammed between the wheel and the rest.

• "Rigidly supported" means the rest cannot wobble or move under normal use.
• "Readily adjustable" means the rest can be quickly repositioned so the gap stays ≤ 1/8 inch as the wheel wears.

(See 1915.134(b).)

Cup-type wheels used for external grinding must be protected by either a revolving cup guard or a band-type guard per the referenced safety code, and all other portable wheels used for external grinding must be provided with safety guards meeting the requirements of paragraph (e), except specific limited exceptions. Requirement in 1915.134(c) explains these requirements.

• Exceptions: A portable wheel may use safety flanges (per paragraph (f)) when the work location makes the guard impossible, or wheels 2 inches or less on a steel mandrel are exempt from the guard requirement per 1915.134(c)(1)–(2).

(See 1915.134(c) and the listed exceptions at 1915.134(c)(1) and 1915.134(c)(2).

Safety flanges are required for portable wheels used for internal grinding unless the wheel is 2 inches or less on the end of a steel mandrel or the wheel is entirely within the work while in use. Requirement in 1915.134(d) and the listed exceptions at 1915.134(d)(1) and 1915.134(d)(2) spell this out.

• Use safety flanges that meet paragraph (f) when internal grinding unless you meet one of the two stated exceptions.

(See 1915.134(d).)

Required safety guards must be mounted to maintain proper alignment with the wheel, and both the guard and its fastenings must be strong enough to retain fragments of the wheel in case of accidental breakage. Requirement in 1915.134(e) requires both alignment and sufficient strength.

• Proper alignment means the guard follows the wheel's plane so it will intercept flying fragments.
• Fastenings and guard material must be selected and maintained so they don't fail under the forces of a bursting wheel.

(See 1915.134(e).)

Safety flanges must be used only with wheels designed to fit them, and only types and designs properly assembled to ensure wheel pieces will be retained if breakage occurs. Requirement in 1915.134(f) requires matching wheel and flange design and correct assembly.

• Use only flanges specified by the wheel manufacturer and assemble them as intended so a failed wheel does not eject large fragments.

(See 1915.134(f).)

All abrasive wheels must be closely inspected and ring-tested before mounting to ensure they are free from cracks or defects. Requirement in 1915.134(g) requires this pre-mounting check.

• "Closely inspected" means visually check for chips, cracks, inclusions, or other defects.
• "Ring test" is required by the standard as a check for hidden cracks before mounting.

(See 1915.134(g).)

Grinding wheels must fit freely on the spindle and must not be forced on, and the spindle nut should be tightened only enough to hold the wheel in place. Requirement in 1915.134(h) prohibits forcing wheels and over-tightening.

• "Fit freely" means the wheel slides onto the spindle without excessive force and sits flush.
• Over-tightening can induce stress in the wheel and increase the risk of breakage.

(See 1915.134(h).)

The power supply must be sufficient to maintain the rated spindle speed under normal grinding conditions, and the rated maximum speed of the wheel must not be exceeded. Requirement in 1915.134(i) requires maintaining rated speed and never exceeding the wheel's maximum rated speed.

• Ensure motors and drives are sized to maintain rated rpm during normal load.
• Never mount a wheel with a lower speed rating than the grinder's actual operating speed.

(See 1915.134(i).)

Employees using abrasive wheels must be protected by eye protection equipment in accordance with Subpart I unless adequate protection is provided by eye shields permanently attached to the bench or floor stand. Requirement in 1915.134(j) specifies this.

• Personal eye protection must meet the criteria in Subpart I unless a permanently attached shield on the grinder provides equivalent protection.
• OSHA's shipyard eye protection interpretation clarifies that protectors must be appropriate to the hazard (for example, welding radiation vs. flying particles) and that ordinary sunglasses do not substitute for required workplace protectors; see the letter at Shipyard eye and face protection (2019-12-30) when selecting protection for specific hazards.

(See 1915.134(j) and Shipyard eye and face protection.)

The general statement in the standard says the maximum angular exposure of the grinding wheel periphery and sides shall not exceed 180 degrees, but specific provisions for floor and bench-mounted external grinding in 1915.134(a) set the tighter limits of 90 degrees (or 125 degrees in the limited below-horizontal exception). Requirement in 1915.134 therefore must be read together: follow the specific limits for bench and floor grinders and the general maximum for other situations.

• For bench/floor external grinding: follow the 90°/125° rules in 1915.134(a).
• For other grinders where no specific provision applies, the general statement retains a 180° absolute maximum.

(See 1915.134 and 1915.134(a).)

Wheels 2 inches or less in diameter that are securely mounted on the end of a steel mandrel are exempt from both the external-guard requirement in 1915.134(c)(2) and the internal-grinding flange requirement in 1915.134(d)(1).

• The exemption applies only to wheels 2 inches or less and when they are securely mounted on a steel mandrel end.

(See 1915.134(c)(2) and 1915.134(d)(1).)

You must use guards and flanges that are mounted and fastened to stay properly aligned with the wheel and that are of sufficient strength and correct design to retain wheel fragments in case of breakage. See 1915.134(e) and 1915.134(f).

• Verify guards and fastenings show no corrosion, cracks, or deformation and that they match the wheel size and orientation.
• Use safety flanges only with wheels designed to fit them and assemble flanges per manufacturer instructions so fragments are contained.

(See 1915.134(e) and 1915.134(f).)

Before starting a grinder, an operator must closely inspect the wheel for cracks or defects, ring-test the wheel, ensure it fits freely on the spindle (not forced on), and tighten the spindle nut only enough to hold the wheel in place. Requirements in 1915.134(g) and 1915.134(h) set these obligations.

• Visual inspection + ring test identify visible and hidden defects.
• Proper fit and moderate nut torque avoid introducing stress that could cause wheel failure.

(See 1915.134(g) and 1915.134(h).)

No. The rated maximum speed of the wheel must not be exceeded; the power supply must maintain the rated spindle speed under normal grinding conditions. Requirement in 1915.134(i) forbids exceeding the wheel's rated speed.

• Always check the wheel's marked maximum rpm and ensure the grinder cannot run faster than that.
• Using a wheel at speeds above its rating increases the likelihood of wheel failure and is a violation.

(See 1915.134(i).)

Yes, permanently attached eye shields on the bench or floor stand are acceptable substitutes for individual eye protection if they afford adequate eye protection for the operation. Requirement in 1915.134(j) allows this substitution when the shield provides adequate protection.

• If the attached shield does not provide adequate protection for all work performed, employees must wear personal eye protection that meets Subpart I.
• For guidance on appropriate eye and face protection for particular hazards, see OSHA's shipyard eye and face protection interpretation at Shipyard eye and face protection (2019-12-30).

(See 1915.134(j) and Shipyard eye and face protection.)

If the work location makes mounting the required portable wheel guard impossible, the employer must use a wheel equipped with safety flanges as described in [1915.134(f)]. See 1915.134(c)(1) and 1915.134(f).

• The safety flanges used must be of the proper type and design and properly assembled so wheel pieces will be retained on breakage.

(See 1915.134(c)(1) and 1915.134(f).)

Yes. Cup-type wheels used for external grinding must be protected by a revolving cup guard or a band-type guard in accordance with the provisions of the United States of America Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels, B7.1-1964, as referenced in [1915.134(c)]. Requirement in 1915.134(c) incorporates that consensus guidance for cup-type wheel guarding.

• Even where the standard references a consensus code, compliance with the guard requirements in 1915.134(e) (alignment and strength) is mandatory.

(See 1915.134(c) and 1915.134(e).)

The work rest gap must be kept at not more than 1/8 inch and should be checked and adjusted as needed during use to maintain that gap. Requirement in 1915.134(b) requires the gap limit; practical maintenance means checking it before use and periodically as the wheel wears.

• Inspect and adjust the rest every time you mount a new wheel and periodically during use when the wheel diameter changes from wear.

(See 1915.134(b).)

If a wheel shows defects during inspection or fails the ring test, or if it does not fit freely on the spindle, you must not mount or use it; instead remove it from service and replace it with a sound wheel that fits properly. See 1915.134(g) and 1915.134(h).

• Mounting cracked or forced-on wheels increases risk of wheel disintegration and serious injury.

(See 1915.134(g) and 1915.134(h).)

The employer is responsible for ensuring abrasive wheels, guards, work rests, flanges, and eye protection comply with the requirements of Part 1915, including [1915.134]. The employer must provide equipment and enforce safe use per the standard. See 1915.134 and the general employer duties in Part 1915.

• Employers must supply compliant guards and PPE, maintain equipment, and train employees in safe operation.
• Competent persons designated by the employer often carry out inspections and determinations; see OSHA guidance on competent persons in shipyards at Competent person requirements in shipyards (2016-04-18) for related obligations.

(See 1915.134 and Competent person requirements in shipyards.)

No; OSHA does not prohibit employers from adopting more stringent measures — employers may and often should provide greater protection than the minimum required by the standard. See 1915.134 for minimum guard and PPE requirements, and OSHA guidance generally allows employers to exceed those minima to better protect employees.

• Providing additional protections (better guards, full-face shields, or stricter maintenance schedules) is permissible and can improve safety.

(See 1915.134 and OSHA letters indicating standards set minimum requirements, e.g., Shipyard eye and face protection (2019-12-30) for context on appropriate PPE selection.)