Subpart O
The top of operating mill rolls on new mill installations must be at least 50 inches above the level on which the operator stands. This 50-inch minimum applies to the actual working level whether it's the general floor, a pit, or a platform. See the Mill roll heights requirement in 1910.216(a)(4).
A safety trip control must be provided in front and in back of each mill and it must be accessible and operate readily on contact. The standard requires both front and rear controls so operators or others can quickly stop the mill from either side. See the Mill safety controls requirement in 1910.216(b)(1).
Pressure-sensitive body bars are required on mills that have a 46-inch roll height or greater and must be installed at the front and back of each such mill so they operate readily by pressure of the operator's body. These bars are intended to stop the mill when an operator's body contacts them. See the Pressure-sensitive body bars provision in 1910.216(b)(1)(i).
Safety triprods must be installed in the front and back of each mill, located within 2 inches of a vertical plane tangent to the front and rear rolls, and the top rods must be no more than 72 inches above the level on which the operator stands. The rods must be accessible and operate readily whether pushed or pulled. See the Safety triprod requirements in 1910.216(b)(1)(ii).
Safety tripwire cables or wire center cords must be installed in the front and back of each mill, located within 2 inches of a vertical plane tangent to the rolls, be no more than 72 inches above the operator level, and must operate readily whether pushed or pulled. This ensures operators can trip the mill quickly from either side. See the Tripwire cable/wire center cord requirements in 1910.216(b)(1)(iii).
Auxiliary equipment must be located so it does not interfere with access to or operation of the mill's safety devices. In practice, locate dividers, support bars, spray pipes, conveyors, strip knives, and similar items so operators can reach and use trip controls without obstruction. See the Auxiliary equipment guidance in 1910.216(b)(3).
Yes. Each pair of in‑running calender rolls must have a safety triprod, cable, or wire center cord provided across the face of the rolls extending the length of the face, and it must operate readily whether pushed or pulled. The device must be within reach of both the operator and the bite. See the Calender face safety trip requirement in 1910.216(c)(1).
On both sides of the calender and near each end of the face of the roll, a cable or wire center cord must be connected to the safety trip and be provided so it will operate readily when pushed or pulled. This provides side access to trip the machine near the ends of the rolls. See the Calender side trip requirement in 1910.216(c)(2).
Mill safety control devices in paragraph (b) may be omitted when the mill is installed so persons cannot normally reach through, over, under, or around to contact the roll bite or be caught between a roll and an adjacent object, provided those inaccessible elements are made a fixed part of the mill. In other words, fixed guards or permanent placement that prevents access can replace the trip controls. See the Protection by location for mills in 1910.216(d)(1).
Calender safety controls in paragraph (c) are not required when the calender is installed so that persons cannot normally reach the roll bite or be caught between a roll and an adjacent object, and provided those inaccessible elements are made a fixed part of the calender. Permanent installation preventing operator access can make trip controls unnecessary. See the Protection by location for calenders in 1910.216(d)(2).
No. All trip and emergency switches must not be of the automatically resetting type; they must require manual resetting. This ensures that the machine stays stopped until a person inspects and restarts it. See the Trip and emergency switches requirement in 1910.216(e).
Stopping distances must be measured with the rolls running empty at maximum operating speed and expressed in inches of surface travel of the roll from the instant the emergency stopping device is actuated. This ensures measurements reflect the worst-case stopping performance. See the Determination of distance of travel in 1910.216(f)(1).
Mills must stop within a distance not greater than 1.5% of the peripheral no‑load surface speed of the roll (measured in feet per minute), while calenders must stop within 1.75% of that speed. To calculate the allowed stopping distance in inches:
Example: if a roll's peripheral no‑load speed is 100 ft/min, a mill's stopping distance must be ≤ 0.18 × 100 = 18 inches, and a calender's must be ≤ 0.21 × 100 = 21 inches. See Stopping limits for mills in 1910.216(f)(2) and Stopping limits for calenders in 1910.216(f)(3)(i).
Yes. The safety trip controls described in paragraph (b) — pressure-sensitive body bars, triprods, and tripwire cables/wire center cords — must operate readily whether pushed or pulled. The standard specifies this operational requirement for the triprods and tripwire/cable and expects body bars to operate by body pressure. See the Types and operation of safety trip controls in 1910.216(b)(1) and its subparts.
Both triprods and tripwire cables or wire center cords must be located within 2 inches of a vertical plane tangent to the front and rear rolls. This close placement helps ensure the tripping device will stop the machine at the earliest risk point. See the Location requirement for triprods and tripwire in 1910.216(b)(1)(ii) and 1910.216(b)(1)(iii).
Mechanical and electrical equipment and auxiliaries must be installed in accordance with 1910.216 and Subpart S of part 1910, and auxiliary equipment must be located to avoid interfering with safety devices. That means follow the general Auxiliary equipment installation rule in 1910.216(a)(3) and the placement guidance in 1910.216(b)(3), plus applicable electrical equipment rules in 1910 Subpart S.
Measurements should be taken with the rolls running empty at the mill's maximum operating speed so that stopping distances reflect the worst-case condition. Measure the inches of surface travel from the instant the emergency stopping device is actuated. See the Measurement procedure in 1910.216(f)(1).
Yes. If the mill or calender is installed so that people cannot normally reach through, over, under, or around to contact the roll bite or be caught between a roll and an adjacent object, and those inaccessible elements are made a fixed part of the equipment, then the trip control devices listed in paragraphs (b) and (c) need not be provided. Ensure the enclosure is truly fixed and prevents access. See the Protection by location rules in 1910.216(d)(1) and 1910.216(d)(2).
Yes. Pressure-sensitive body bars are specifically required on the front and back of each mill that has a roll height of 46 inches or more. For mills with rolls under 46 inches, the standard does not mandate body bars, though other trip devices may be required. See the Pressure-sensitive body bar threshold in 1910.216(b)(1)(i).
Yes. The safety tripping device across the calender face must be readily accessible and located within reach of both the operator and the bite so it can be used quickly to stop in‑running rolls. This placement reduces response time if a worker or material is caught at the bite. See the Calender face trip accessibility requirement in 1910.216(c)(1).