Fuel Tank Entry on a Barge
A shipyard is preparing to clean and inspect an empty fuel tank on a 240-foot barge. The tank has been pumped out but not cleaned; sludge remains. The tank access is a 20-inch manhole. A competent person tests the atmosphere at the manhole and gets 15.5% oxygen, 120 ppm hydrogen sulfide, and no flammable gas reading. The tank has not been ventilated. A worker says he entered briefly yesterday to retrieve a dropped wrench and felt dizzy. The supervisor wants two workers to enter today with dust masks and a rope tied around the wrist, while a coworker stands at the manhole. The shipyard has a rescue service 20 minutes away and no on-site rescue team. The tank has one manhole and no internal lighting.
1. Classify the tank under OSHA's shipyard confined space requirements and identify the hazards.
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The tank is a permit-required confined space. It has limited entry and exit through a single 20-inch manhole, is not designed for continuous occupancy, and contains a hazardous atmosphere. The oxygen reading of 15.5% is below the 19.5% minimum, creating an oxygen-deficient atmosphere; 120 ppm hydrogen sulfide exceeds OSHA's exposure limits and is above the IDLH value of 100 ppm, so it can cause immediate incapacitation. Sludge can also release flammable or toxic gas. The prior dizziness is a warning sign. Under 29 CFR 1915 Subpart B, entry requires a permit, pre-entry and periodic testing, forced ventilation, isolation, an attendant, communication, and rescue capability. The supervisor's dust masks and wrist rope are not adequate. No entry should occur until the space is ventilated, retested, and controlled.
2. What controls must be in place before any entry?
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Before entry, the employer must issue a written permit, isolate and blank the tank, lock out energy sources, ventilate with forced air, and retest the atmosphere from outside. Entry can proceed only if oxygen is 19.5–23.5%, hydrogen sulfide is below the permissible limit, and flammable gas is safe. If the atmosphere cannot be made safe, entrants need supplied-air respirators, not dust masks. A full-body harness with a retrieval line is required for vertical entry; a rope around the wrist is dangerous and unacceptable. A trained attendant must stay at the manhole, maintain communication, and summon rescue. The rescue service must be notified and able to respond promptly; a 20-minute away service may be too slow unless the employer can show it is capable. The employer must also provide lighting and training.
3. What should the employer do about the worker who entered yesterday?
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The employer should treat the prior entry as an incident. The worker entered a permit-required confined space without testing, ventilation, a permit, an attendant, or rescue, and reported dizziness-a symptom consistent with oxygen deficiency or hydrogen sulfide exposure. The employer should remove the worker from further exposure, arrange a medical evaluation, investigate how the entry happened, and retrain the crew. If the dizziness required medical treatment beyond first aid, the case may be recordable; if it was only a transient symptom with no treatment, recordability is less likely, but the near-miss must still be investigated. The employer should also review its permit system and enforce the prohibition on unauthorized entry. Disciplining the worker alone would not fix the system and could chill reporting; the focus should be on supervision, training, and entry control.