Process: Surface Preparation and Descaling

Description

During this process, surfaces of steel ships are prepared for painting.1

Steam or fresh water under high pressure is played onto the undersides of hulls to remove barnacles and other growth. Exterior surfaces may be sandblasted, but chipping, using chipping hammers, wire brushes and grinders, powered either pneumatically or electrically, is more common. Interior preparation is usually done by hand, although special equipment may be used in tanks and in void or double bottoms.1

  • Chemical paint and rust removers may be used in preparing metal surfaces.
  • A commercial diving operation may be used to clean the undersides of hulls while the ship remains in the water. For example, divers may manually steer a hull cleaning device called a SCAMP, which is comprised of rotating steel brushes and an impeller to vacuum the material removed from the hull.
Equipment
  • Scaffolding and ladders
  • Abrasive blasting equipment - rubber hose lines, compressors, nozzles, couplings, etc.
  • Electrical or pneumatic hand tools
  • Tackle
  • Flame torches
  • Personal protective clothing - hats or hoods, dust masks, goggles, face shields, respirators, gloves
  • SCAMP - an underwater hull cleaning device operated by divers
Associated Hazards
  • Hearing loss from noise - noise is prevalent. Pneumatic chippers used in descaling generate especially high levels of noise.
  • Lead poisoning during stripping and chipping operations - flame stripping can vaporize lead paints. Chipping and cutting-up where lead paints are present creates lead-containing dusts.2
    For standards covering explosive and other dangerous atmospheres, see 29 CFR 1915, Subpart B.
  • Thermal burns during steam cleaning operations.
  • Drowning, injuries from falls - surges from pressure drops in hose lines pose a special hazard. Section 29 CFR 1915.34(c)(3)(v) requires that abrasive blasters wear safety belts where railings fail to provide adequate protection against falls. For standards covering scaffolds, ladders and other working surfaces, see 29 CFR 1915, Subpart E. Drowning results from falls from staging, decks, and end and wings wall of dry docks. Work over and near water requires life jackets, but compliance is difficult to enforce.3
    For standards covering types and maintenance of lifesaving equipment, see 29 CFR 1915.158. For standards covering personal flotation devices, which references Coast Guard standards, 46 CFR 160 and 33 CFR 175.23, see 29 CFR 1915.158(a). OSHA has issued two instructions that concern falling hazards. OSHA instruction STD 03-10-006 [STD 3-10.6] covers restrictions on welding from float and ship scaffolds and clarifies a contradiction between 29 CFR 1926.451(w) and 29 CFR 1926.451(a)(18) by allowing welding from these scaffolds providing the supporting ropes are without flaws and of adequate size. OSHA instruction STD 1-11.2B concerns work platforms suspended from lattice or hydraulic crane booms, and clarifies 29 CFR 1926.550(b)(2) by allowing the use of such platforms only when the procedure is safer than alternative available work practices.
  • Ruptured air hose lines - see 29 CFR 1915.34(c) for standard covering abrasive blasting hoses, nozzles, and couplings.
  • Eye injuries from scale and rust are a prevalent injury; see 29 CFR 1915.153(a) for standard covering eye protection equipment, which references the American Standard Safety Code for Head, Eye and Respiratory Protection, Z2.1.
  • Respiratory damage from abrasive particles and dusts during abrasive blasting - see 29 CFR 1915.34(c) for standard covering personal protective equipment in abrasive blasting. Silica may pose an additional hazard during abrasive blasting.
  • Electrocution from portable electric hand tools and lights - portable tools and lights are used extensively. Double-insulation is preferred to grounding.3
    For standards covering portable hand tools, see 29 CFR 1915.132.
  • Drowning, traumatic injury, and decompression sickness among divers while using underwater hull cleaning devices - although diving depths are low, the operation is hazardous due to proximity to machinery and low visibility. Section 29 CFR 1910, Subpart T covers the standard for commercial diving operations. The cleaning equipment should be guarded and equipped with a dead-man control to avoid diver contact with moving brushes or the current created by the impeller.
  • Exposure to silica during abrasive blasting operations.
References

1 Best, A.M. "Ship descaling." Loss Control Engineering Manual, (1975).

2 Haglind, O. "Occupational health in the shipbuilding industry." Safety and Health in Shipbuilding and Ship Repair. Geneva: International Labour Office, 1972.

3 Netterson, R.W. "Accident prevention in shipbuilding and repairing." Safety and Health in Shipbuilding and Ship Repair. Geneva: International Labour Office, 1972.