PR-450 Hydraulic Press — Die Change Isolation
Die change on a 450-ton hydraulic press. Covers accumulator stored energy, slide gravity restraint, and nitrogen gas-spring die cushions that have no lockable isolation device.
How Setyr addresses Manufacturing andAutomotive →
It refers to equipment that does not exist and illustrates the elements 29 CFR 1910.147(c)(4)(ii) requires a procedure to contain. It is not a document to adopt. Under (c)(4)(i) the employer must develop and document energy control procedures specific to their own machines, and under (c)(6) must inspect them at least annually.
12 points, in sequence
480V fused main disconnect at the press control cabinet. Feeds the hydraulic power unit, controls and slide.
Method: Open the disconnect, lock in the OFF position, then prove dead at the load side before proceeding.
Caution: Opening the main does NOT drain the accumulator. The slide can still move under stored hydraulic pressure until the accumulator dump is complete.
Control transformer breaker feeding the PLC, light curtains and two-hand controls.
Method: Open the breaker and lock. Confirm the operator panel is dark.
Caution: Light curtains are a safeguarding device, not an isolation device. They stop being protective the moment control power is dropped.
Hydraulic power unit pump motor disconnect, 75 hp.
Method: Open, lock, and prove dead at the motor starter load terminals.
Caution: The pump can restart on control power alone if only the main is opened. Isolate the HPU separately.
Accumulator bank isolation valve. Nitrogen-backed piston accumulators, 3000 psi working pressure.
Method: Close the valve and fit a lockable valve cover. This isolates the bank from the ring main but does not empty it.
Caution: Closing this valve traps pressure on the accumulator side. It must be followed by the dump valve.
Accumulator dump valve to tank. Releases trapped hydraulic pressure from the accumulator bank.
Method: Open the dump valve and lock it OPEN. Hold open for the full bleed-down, then confirm the accumulator gauge reads zero before proceeding.
Caution: A nitrogen-backed accumulator holds full working pressure with the pump off and the main disconnect open. Gauge at zero is the verification — elapsed time alone is not.
Main hydraulic supply valve from the HPU ring main to the press manifold.
Method: Close and lock the valve.
Plant air supply to the slide counterbalance cylinders and die cushion.
Method: Close the supply valve and lock.
Caution: The counterbalance carries slide weight. Dropping counterbalance air before the safety blocks are set lets the slide settle.
Safety blocks for the slide. Two rated blocks set between the bolster and the slide face.
Method: Set both blocks, engage the interlock, and confirm the block-in-place switch is made. Blocks must be ENGAGED, not removed.
Caution: Gravity is not isolated by any valve or breaker on this machine. Once counterbalance air is vented the slide is restrained by these blocks alone.
Counterbalance air vent, downstream of the supply valve.
Method: Open the vent and lock open. Confirm the counterbalance gauge reads zero.
Caution: Vent only AFTER the safety blocks are set and the block-in-place switch is made.
Nitrogen gas-spring die cushions in the lower die shoe. Self-contained cylinders with no lockable isolation device.
Method: Bleed each cylinder at its fill port using the manifold bleed tool. Confirm zero at the manifold gauge and tag each cylinder as bled.
Caution: These cannot be locked out — there is no device to lock. They hold several thousand psi with every other energy source isolated, and they release into the die space where hands go. Treat as live until individually bled and verified.
Cooling water supply to the die and the hydraulic oil cooler.
Method: Close and lock the supply valve.
Die-change hoist and bolster cart supply, fed from a separate panel.
Method: Do NOT isolate. Confirm live before the die set is moved.
Caution: The die cart and hoist move the die set. Isolating them along with the press strands a die half out of the bolster.
What your site must supply
This example is structurally complete and factually generic. The things below are the things only you can know — and they are exactly what makes a procedure yours.
- Your own asset and isolation-point tag numbers. The tags shown are illustrative and refer to equipment that does not exist.
- The actual location of every disconnect, valve and vent on your equipment.
- Measured stored-energy magnitudes and the dwell time required to dissipate them.
- Your verification method for each point, and who is authorised to perform it.
- Any additional energy sources present on your equipment and absent here.
Author this properly, once
Setyr holds procedures like this as living documents — bound to real isolation points, with lock registries, group lockout, person-in-charge custody and periodic review built in.