Setyr worked example — PR-450 Hydraulic Press — Die Change Isolation Not approved for use. Version 1 · 2026-09-25
Worked example only — your site must author, review and approve its own
procedure under 29 CFR 1910.147(c)(4). setyr.com/procedures
PR-450 Hydraulic Press — Die Change Isolation
Metal forming
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.
This is a worked example, not a procedure you can adopt. It describes equipment that does not exist, with illustrative tag numbers.
29 CFR 1910.147(c)(4) requires the employer to develop, document and
utilise energy control procedures specific to their own machines, and (c)(6)
requires the employer to inspect those procedures periodically. Neither duty
can be delegated to a vendor or discharged by this document.
Isolation points
| # | Tag (illustrative) | Type | Disposition | What it does and why | Dwell |
|---|---|---|---|---|---|
| 10 | PR-450-MAIN-ISO | Disconnect | Isolate & lock | 480V fused main disconnect at the press control cabinet. Feeds the hydraulic power unit, controls and slide. Caution: Opening the main does NOT drain the accumulator. The slide can still move under stored hydraulic pressure until the accumulator dump is complete. Open the disconnect, lock in the OFF position, then prove dead at the load side before proceeding. | — |
| 20 | PR-450-CTRL-ISO | Breaker | Isolate & lock | Control transformer breaker feeding the PLC, light curtains and two-hand controls. Caution: Light curtains are a safeguarding device, not an isolation device. They stop being protective the moment control power is dropped. Open the breaker and lock. Confirm the operator panel is dark. | — |
| 30 | PR-450-HPU-ISO | Disconnect | Isolate & lock | Hydraulic power unit pump motor disconnect, 75 hp. Caution: The pump can restart on control power alone if only the main is opened. Isolate the HPU separately. Open, lock, and prove dead at the motor starter load terminals. | — |
| 40 | PR-450-ACC-ISO | Valve | Isolate & lock | Accumulator bank isolation valve. Nitrogen-backed piston accumulators, 3000 psi working pressure. Caution: Closing this valve traps pressure on the accumulator side. It must be followed by the dump valve. Close the valve and fit a lockable valve cover. This isolates the bank from the ring main but does not empty it. | — |
| 50 | PR-450-ACC-DUMP | Bleed | Isolate & lock | Accumulator dump valve to tank. Releases trapped hydraulic pressure from the accumulator bank. 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. Open the dump valve and lock it OPEN. Hold open for the full bleed-down, then confirm the accumulator gauge reads zero before proceeding. | 180s |
| 60 | PR-450-HYD-SUP | Valve | Isolate & lock | Main hydraulic supply valve from the HPU ring main to the press manifold. Close and lock the valve. | — |
| 70 | PR-450-AIR-SUP | Valve | Isolate & lock | Plant air supply to the slide counterbalance cylinders and die cushion. Caution: The counterbalance carries slide weight. Dropping counterbalance air before the safety blocks are set lets the slide settle. Close the supply valve and lock. | — |
| 80 | PR-450-SAFETY-BLK | Block | Apply & verify | Safety blocks for the slide. Two rated blocks set between the bolster and the slide face. 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. Set both blocks, engage the interlock, and confirm the block-in-place switch is made. Blocks must be ENGAGED, not removed. | — |
| 90 | PR-450-AIR-VENT | Vent | Isolate & lock | Counterbalance air vent, downstream of the supply valve. Caution: Vent only AFTER the safety blocks are set and the block-in-place switch is made. Open the vent and lock open. Confirm the counterbalance gauge reads zero. | 60s |
| 100 | PR-450-N2-CUSH | Bleed | CANNOT BE ISOLATED | Nitrogen gas-spring die cushions in the lower die shoe. Self-contained cylinders with no lockable isolation device. 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. Bleed each cylinder at its fill port using the manifold bleed tool. Confirm zero at the manifold gauge and tag each cylinder as bled. | 120s |
| 110 | PR-450-CW-SUP | Valve | Isolate & lock | Cooling water supply to the die and the hydraulic oil cooler. Close and lock the supply valve. | — |
| 120 | PR-450-HOIST-ISO | Disconnect | KEEP ENERGISED | Die-change hoist and bolster cart supply, fed from a separate panel. Caution: The die cart and hoist move the die set. Isolating them along with the press strands a die half out of the bolster. Do NOT isolate. Confirm live before the die set is moved. | — |
What your site must supply
- 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.
Authorship and validation
This example was authored by Setyr for domain validation. It is not derived from any customer's controlled documents. It illustrates the elements 29 CFR 1910.147(c)(4)(ii) requires a procedure to contain — it does not certify compliance, which is a property of an employer's programme rather than of any document.