Hand Lance in a Contaminated Pit
At a refinery during a turnaround, a two-person crew is assigned to remove scale from the shell side of a horizontal heat exchanger with a 15,000 psi hand lance. The exchanger sits in a concrete pit 8 ft deep with a fixed ladder. The operator plans to stand on the pit floor and work the lance overhead at chest height while the helper stands directly behind him holding the hose off the deck. The pit was nitrogen-purged the previous shift, but no gas test has been logged for this entry, and the sump pump is tagged out for repair, leaving about 6 in. of water on the floor. Four hours of daylight remain. The operator's face shield is scratched, his rain suit has a torn cuff, and the 50-ft, 1/4-in. high-pressure hose has no whip check at the lance connection. The helper asks whether he should move to the opposite side to steady the lance.
1. Identify the stop-work hazards in this setup and explain which ones must be corrected before the lance is pressurized.
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The crew should stop before pressurizing. Each finding below is a hazard that schedule pressure does not override:
- Atmosphere and confined space: An 8-ft pit with a ladder is a permit-required confined space. A nitrogen purge can leave an oxygen-deficient atmosphere, and no gas test is logged for this entry. Test for oxygen, flammables, and toxic gases before entry and continuously while working; ventilate if needed.
- Water in the pit: About 6 in. of standing water with the sump pump tagged out creates a slip hazard, hides the jet and hose, and adds an electrical risk if equipment is wet. Dewater or control the water before entry.
- Damaged PPE: A scratched face shield reduces visibility and can hide a crack; a torn rain suit cuff lets high-pressure spray reach skin. Replace both before work.
- Missing whip check: At 15,000 psi, a failed coupling can whip the hose. Install a whip check and secure the connection.
- Helper position: Standing directly behind the operator puts the helper in line with lance thrust and hose rupture. Reposition before pressurizing.
The reasoning is that a high-pressure water jet does not need a visible leak to injure; stored energy, poor visibility, and an oxygen-deficient pit compound one another.
2. Where should each crew member be positioned during the work, and what communication and emergency controls should be in place?
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Positioning should keep both people out of the line of thrust and out of the pit when possible.
- Operator: Stand on a stable platform or scaffold that supports the lance, not on a wet pit floor under an overhead lance. Keep the lance tip pointed away from the body and never straddle the hose or lance. Use a lance support if the exchanger geometry allows it.
- Helper: Operate the pump controls from outside the pit, with a clear view or radio contact and an unobstructed emergency stop. The helper should not hold the hose to steady the lance; that places hands near a pressurized connection and puts the helper in line with a possible hose failure.
- Barricade: Establish a barricade around the pit and pump area so other workers do not walk into the jet path or hose run.
- Communication: Use two-way radios or a clear line-of-sight signal. Agree on a stop signal before pressurizing. The helper controls the pump, not the operator at the lance.
The reasoning is that the person at the lance cannot safely control both the jet and the pump, and a helper behind the operator cannot see a hose failure developing in front of the operator.
3. Put the corrective actions in the order you would complete them before normal operation resumes.
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A defensible sequence is:
- Stop and secure: Shut down the pump, relieve pressure, and lock out the pump drive.
- Test the atmosphere: Gas-test the pit and document the results; ventilate and retest if the entry is authorized.
- Control water: Restore the sump pump or dewater the pit, then verify a stable walking surface.
- Replace PPE: Fit a clear, undamaged face shield and intact rain suit; check gloves and hearing protection.
- Inspect and repair the pressure connection: Inspect the hose, coupling, and lance; install a whip check and safety cable.
- Reposition the crew and barricade: Operator on a stable platform, helper at the pump controls, barricade in place, communications tested.
- Restart at low pressure: Pressurize slowly, check for leaks from a safe distance, and only then bring the lance to working pressure.
The order matters because testing the atmosphere and controlling water protect the people who must enter the pit to fix the hose and PPE; those fixes cannot be done safely in an oxygen-deficient, flooded pit.