Barge Operations

Types of Pumps on Tank Barges

Reciprocating Pumps

  • Use backward and forward movement to transport liquids.

  • Composed of a piston, plunger, or diaphragm that moves during suction and delivery strokes.

  • Air Diaphragm Reciprocating Pumps:

    • Are positive displacement pumps.

    • Typically do not need priming.

    • Commonly used for stripping cargo, removing slops, and dewatering; frequently found on Kirby barges.

Rotary Gear Pumps

  • A type of positive displacement pump.

  • Flow generated by a rotor and gear assembly that displaces the liquid and sends it to the discharge port.

  • Commonly used in systems for stripping cargo tanks and fuel transfer.

Screw Pumps

  • Positive displacement pumps utilizing one or several screws to transport molten solids and liquids along their axis.

  • Often used on tank barges for high viscosity cargoes, such as asphalt.

Centrifugal Pumps

  • Designed to move liquids using one or more impellers that increase the liquid's velocity and pressure.

  • Key Features:

    • Not considered positive displacement.

    • High flow rates, which can vary with changes in the rotation speed and discharge piping configuration.

    • Allows throttling of flow rate with pump rotation speed control or a valve in the discharge line, minimizing excessive pressure buildup.

  • Deep Well Centrifugal Pumps:

    • Most common for transferring cargoes on tank barges.

    • Comprised of one or more shaft-driven impellers within a deep well casing, with the suction impeller submerged in the liquid cargo.

    • Converts liquid flow velocity created by impellers into pump pressure for discharge.

Operational Hazards and Safety Precautions

  • Significant risks in marine pumping operations include personal injury, pump damage, and fire or explosion.

  • Personal Protection:

    • Use PPE when checking hose and seals.

    • Avoid heated surfaces and spinning drive shafts; ensure guards are in place.

    • Hearing and eye protection is mandatory.

  • Pump Maintenance:

    • Gearhead, drive shaft, and PTO must be adequately lubricated.

    • Before engaging the PTO, confirm no resistance or restrictions exist.

    • The pump must always be properly primed and never run dry to prevent overheating and potential fire hazards.

    • Avoid low flow rates, which can increase heat and cause damage.

    • Operate within recommended flow rates to prevent cavitation and excessive vibrations.

Components of Pump Systems

  • Key components include:

    • Cargo Pump Relief Valve: Limits discharge line pressure.

    • Pump Bleader Line: Used for priming.

    • Pressure Gauge: Monitors discharge pressure.

    • Check Valve: Prevents backflow.

    • Check Valve Bypass: for priming the pump.

    • Discharge and Suction Lines: Facilitate cargo movement.

  • The Master Suction Valve enables cargo flow from the main cargo line to the pump.

  • Deep Well Stripping Lines: Remove cargo residues efficiently.

Pump Mechanical Seals and Maintenance

  • Mechanical Seals: Prevent leakages where the rotating shaft enters the pump housing.

  • Seal failure can lead to hazardous liquid releases.

  • Common seal failure causes:

    1. Dry Running: Causes extra friction and heat leading to damage.

    2. Shocks/Vibrations: High engine speed engagement can damage seals.

    3. Pressure Variability: Can accelerate wear.

  • Maintain steady flow rates to prolong seal life.

  • Some cargo pumps utilize Packing Glands instead of mechanical seals.

Operating Procedures and Emergency Protocols

  • Control Systems: Pumps operated locally at the engine.

    • Engage/disengage via the PTO handle while the engine is at idle.

    • Throttle controls the pump speed.

  • Emergency Protocols:

    • At least one remote shutdown station should be accessible within 100 feet of the engine.

    • Quick shutdown systems restrict air intake, ensuring prompt engine stop during emergencies.