Conveyor Lockout/Tagout Example: Locking Out and Restoring C-3

Locking Out and Restoring Conveyor C-3: Lesson Overview

In this lesson you'll apply everything to one machine, using Conveyor C-3's own lockout procedure. You'll decide what to do about a jam ten minutes before the end of a shift, then follow C-3's procedure step by step: shut C-3 down and isolate it at its main disconnect and hydraulic supply valve, lock it out as a group of two technicians and a contractor, restrain its stored energy in the procedure's order, then verify isolation with the try-out and restore C-3 to service.

The Shift-End Crisis

Ten minutes before the shift change on Line 2, a carton jams inside the guarded section of Conveyor C-3. Two technicians and an outside contractor arrive to clear it. An operator suggests hitting the emergency stop and reaching in through guard door G2 to save time. What will you do?

Choose Your Method

Ten minutes left on the shift. How will you clear the jam? Check the C-3 procedure if you need to, then choose. The emergency stop feels safe, but it only stops C-3 through the control circuit. DS-C3 is still on, HV-C3 is still open, and the 250-pound take-up counterweight still holds the belt in tension. If the counterweight drops, the belt and pulleys can move with your hand in the take-up area. Choose again. The belt is stopped, but nothing is isolated. Main disconnect DS-C3 is still on, and 1,500 psi is still in the hydraulic line. A start from the push button station or the Line 2 HMI, or the trapped pressure, can move the belt while your hand is in it. Choose again. Right. The C-3 procedure says clearing a jam inside the guarded section is not minor servicing. You notify the operators, stop C-3 at PB-C3, lock DS-C3 and HV-C3, install BC-C3, insert TP-C3, bleed BV-C3 to zero and try START. Only then do you open the guard door. The shift runs a few minutes over.

Steps 3–5: Shut Down, Isolate, Lock

You chose to lock out C-3, so now you follow its procedure, step by step. Steps 1 and 2 are done: the affected employees have been notified, and you've reviewed the procedure. Step 3: if C-3 is running, press STOP at push button station PB-C3 and turn selector switch SS-C3 to OFF. Step 4: isolate it. At building column B-14, move the handle of main disconnect DS-C3 down to OFF. Next, close the hydraulic supply valve, HV-C3, at the HPU-C3 outlet under the incline: turn its red handle a quarter turn so it sits across the pipe. Step 5: lock DS-C3 with your assigned lock, and fit the ball valve lockout device on HV-C3 with your lock. The pressure trapped behind HV-C3 is still there. Step 6 deals with it, in the procedure's order.

Coordinating the Group

Three people are working on C-3, so the procedure calls for group lock box GLB-C3. The lead technician notified the affected employees and locked out C-3. Technician 1, Technician 2, and the outside contractor each need a personal lock on the box. Technician 1's is on. Drag the other two to the box. All three personal locks are on group lock box GLB-C3. Under OSHA's lockout standard, each authorized employee affixes a personal lock to the group lockout device when they begin work. Now Technician 2 finishes her part first and is leaving. What happens to the locks? Right. Each authorized employee affixes a personal lock when they begin work and removes it when they stop working on the machine. Technician 1 and the contractor keep their locks on until they finish. Then her lock protects no one, and someone else has to remove it. Removing another employee's lock is allowed only under the employer's documented procedure for an employee who is not available. Choose again. If the lead takes everyone's locks off, someone who is still working loses their protection without knowing it. Each authorized employee removes their own device when they stop working on the machine. Choose again.

Step 6: Stored Energy

With DS-C3 and HV-C3 locked, step 6 is stored energy, released or restrained in the procedure's order. Start at the foot of the incline. Install belt clamp BC-C3 so the loaded cases cannot roll back. Next, move to the tail pulley. Insert the red take-up pin TP-C3 to hold the 250-pound counterweight. Finally, open bleed valve BV-C3. Wait until pressure gauge PG-C3 reads zero, and leave BV-C3 open.

Step 7: Verify Isolation

Step 7: verify isolation, before anyone opens a guard door. First, check that no one is inside the guarded section or on or near the incline. Then do the try-out on push button station PB-C3. Stop! You didn't check the selector switch. You must turn SS-C3 to HAND before pressing START to properly test the circuit. The belt remains still and the pump does not start. Pressure gauge PG-C3 correctly reads zero. Finally, return selector switch SS-C3 to OFF. Verification is complete. Had the belt moved, the pump started or PG-C3 shown pressure, you would stop: C-3 is not isolated, and no guard door opens until the cause is found and corrected.

Lesson Recap

Let's review the critical safety rules for Conveyor C-3. Remember that clearing jams inside guard doors G1 through G4 is never minor servicing—it requires a full lockout every time. Always restrain stored energy in the exact order of incline, then take-up, then hydraulic pressure. And in group work, each of you puts your own lock on GLB-C3 and takes it off when you stop working.