Tanker: Vessels and Vehicles for Transporting Liquids, Gases and Bulk Fluids

Principal types and characteristics

Common tanker categories include:

• Oil tankers — seagoing ships that move crude oil and refined products; classified by size classes such as Handy, Aframax, Suezmax, VLCC and ULCC and often built with segregated tanks and double hulls.
• Chemical tankers — usually smaller vessels or parcel tankers with multiple coated or stainless-steel tanks to carry different, sometimes reactive, substances.
• LNG and LPG carriers — fitted with insulated or pressurised tanks to keep gases liquefied at very low temperatures or moderate pressure, using specialized containment systems.
• Tanker trucks and railcars — road and rail vehicles sized for local distribution of fuels, milk, water and industrial chemicals.
• Barges and naval oilers — unpowered or auxiliary vessels used for coastal transfer, inland waterways or underway replenishment at sea.

Design features and systems

Tanker design emphasises compartmentalisation, piping and pumping arrangements, corrosion-resistant materials, and safety systems. Typical features include multiple cargo tanks, segregated ballast systems, inert gas and gas-detection systems to reduce explosion risk, and structural measures to preserve stability and strength under varied loading conditions. Gas carriers add thermal insulation and boil-off management; chemical tankers use coatings and stainless steel linings.

Operations, loading and unloading

Loading and discharging use dedicated manifolds, pumps and hoses; operations follow strict procedures to control vapour, prevent contamination between cargos and protect crew. Common operational terms include bunkering (fuel transfer), lightering (transferring cargo to smaller vessels) and ship-to-ship transfer. Proper planning of tank sequence and ballast is essential to maintain hull stresses and stability.

History, regulation and safety

Bulk liquid transport expanded with the growth of the petroleum and chemical industries from the 19th century onward. High-profile spills in the late 20th century led to tightened national and international rules, adoption of double-hull standards, stronger crew training and pollution-prevention regimes enforced by classification societies and maritime authorities. Modern safety practices combine technology, regulation and emergency response planning to reduce accident and environmental impact.

Importance and contemporary issues

Tankers are vital to energy markets, industrial supply chains and emergency services. Current concerns focus on emissions from ships, ballast water management, aging fleet renewal, cyber-physical safety of automated systems and continued improvement of spill prevention and response capability.