LPG is highly portable. It can be transported in a number of different ways, usually in its liquid state as it takes up less space than when it is a gas. In this guide, we take a look at some of the ways LPG is transported and how LPG brokerage works:
Ship
Large tankers can be used for transporting LNG across oceans. Usually this is done on a type of vessel called a Very Large Gas Carrier (VLGC).
Intermodal ISO tank containers
ISO tank containers are stackable and can be used to move LPG via different modes of transport (i.e. ship, rail, or truck) without having to unload and reload the LPG.
Rail
LPG can be moved in bulk via tanker rail cars. Transporting LPG in this way is typically only used in specific instances, such as from well sites to terminals. It also requires specialist loading and unloading facilities at terminals either end.
Pipelines
Sometimes special pipelines are used to transport LPG from gas fields to storage terminals. However, these are very expensive to build which means their use is not widespread.
Reticulated gas systems
LPG reticulation systems are used by some communities or building estates. This involves LPG being moved from a central storage tank to individual homes, each of which have a metre.
Road
Large road tankers are used to move large quantities of LPG from terminals and depots. This is usually the way that high volume users (e.g. petrol stations and large factories) get deliveries.
Local bobtail tankers
Bobtail tankers (also known as rigid tankers) are often used to make local bulk deliveries of LPG to end users. These use a pump and hose reel arrangement to dispense the gas. Using local tankers has the advantage of allowing customers to automatically schedule deliveries without waiting to empty a cylinder completely.
Cylinder truck delivery
Special trucks supply low volume users with bottles of LPG on an exchange basis (for example, those used for BBQs and forklifts). This sees the driver deliver full cylinders and remove empty gas bottles, ready to be refilled.
People power
Bike carts are used in some countries to deliver LPG across short distances, particularly in cities with heavy traffic.
What is LPG?
LPG stands for liquefied petroleum gas. It gets its name from the fact is can easily be converted to liquid form. The key characteristics of LPG are that it is:
- Colourless
- Combustible (i.e. it is flammable and can be burned)
- Odourless (however a perfume is added to LPG cylinders to help with gas leak detection)
A by-product of crude oil extraction, LPG is a fuel gas made from a mix of the following hydrocarbon gases:
- Propane
- Propylene
- Butylene
- Isobutane
- N-Butane
In most instances, LPG is used in its gaseous (as opposed to liquid) form with the gas being ignited and burned to create energy. LPG has a broad range of uses in daily life, such as in:
- Heating appliances
- Cooking equipment
- Aerosols
- Refrigerant
- Vehicles
LPG is known to emit 33% less CO2 than coal making it the lowest carbon conventional fuel available off-grid in Britain. This makes it a popular choice for those without mains gas access.
Difference between LPG and LNG
There are several key differences between LPG and LNG, including:
- LPG is liquefied under light pressure. LNG is liquefied cryogenically
LNG requires extremely low temperatures to turn it into its liquid form. LPG, however, only needs light pressure. - LPG is stored and transported differently to LNG
LNG needs to be stored and shipped in cryogenic tanks, which comes with certain safety risks. Furthermore, it usually requires special pipelines to transport it. LPG does not require this. - LPG can be used directly from the vessel, LNG cannot
LNG needs to be converted into gaseous form before it can be used. This is done via a process called regasification and requires vaporizers. - LPG is less flammable than LNG
There are a number of reasons for this, for example, LPG can be stored at room temperature, requires low storage pressure and, unlike LNG, has no risk of rapid phase transition (RPT).
What are LPG ships?
LPG ships are also known as gas carrier ships. These vessels are specially designed ocean-going vessels which have a sole function: to transport all types of LNG and LPG from one place to another via their in-built tankers. LPG ships make up the majority of the wider gas tanker fleet with over 800 vessels currently registered as LPG carriers.
Different types of LPG ships
There are three main types of LPG vessel:
Fully pressurised ships
These can carry gases up to 3,500 m³ in their spherical or cylindrical steel tanks and are designed to work at pressures up to 17.5 kg/cm² and at a minimum temperature of -45°C. As the gas is carried at ambient temperature, these vessels do not have insulation and are built with ordinary grade thick steel walls.
Semi-pressurised and semi-refrigerated ships
Typically cylindrical in shape, semi-refrigerated vessels can transport up to 5,000 m³ of LPG and are built to handle pressures up to 8.5 kg/cm² and minimum temperatures of -10°C. Semi-pressurised and fully-refrigerated ships, however, can transport up to 15,000 m³ of LPG in cylindrical or spherical tanks. These are built to work at a maximum pressure of 5 kg/cm² and a minimum temperature of -48°C. These vessels have re-liquefaction plants fitted on-board to cool/heat the gas as required when filling and discharging the tanks.
Fully refrigerated ships
These VLGCs are prism-like in shape and can carry 15,000 – 85,000 m³ of LPG. Well-suited for long voyages, their tanks can take pressure up to 0.28 kg/cm² and work at a minimum of – 50°C.
LPG vessels can also be categorised according to their size and characteristics:
Handy gas carriers
This is the name given to LPG vessels of 15,000 to 25,000 cbm. Usually used on short to medium-haul routes, handy gas carriers can be semi-refrigerated, fully-refrigerated or pressurised ships.
Mid-sizes
This refers to fully-refrigerated LPG vessels of 25,000–50,000 cbm. They are usually used on intra-regional routes (within the Americas or Asia) and medium-haul cross-trades (in the North Sea and Europe).
LGC
This refers to LPG vessels of 50,000–70,000 cbm which are usually used to carry LPG between ports.
Very Large Gas Carriers (VLGC)
This refers to LPG vessels of 70,000 cbm and above. Normally fully-refrigerated, these vessels are typically used on long-haul trade routes from the US and Middle East Gulf to Asia.
What is the difference between LNG and LPG ships?
The individual characteristics of LNG and LPG mean they need to be transported under different conditions, and therefore require vessels with different attributes to account for this. There are some key differences between LNG and LPG ships, including:
- The tanker’s pressure
LPG needs to be transported under high pressure or low temperature and so LPG vessels are either fully pressurised or fully-refrigerated. - The tanker’s outer design
LNG tankers are cylindrical while LPG tankers can be cylindrical or have flat surfaces. - The tanker’s inner design LNG has to be transported at very low temperatures to remain in its liquid state. This requires the inside of LNG tankers to be able to withstand extremely low temperatures, which is done by installing membrane tanks with high vacuum multilayer insulation.
LPG shipping rates
LPG shipping rates are set to be impacted by various factors over the next year, in particular:
- 45 new VLGCs scheduled for delivery in 2023
- New trade between the US and Europe predicted to continue rising
- Post-pandemic slowdown in some regions
- Iran sanctions
- Geopolitical tensions
- Weak petrochemical margins
- What the IMO’s CII regulations mean for older LPG carriers
As the world’s most comprehensive and widely recognised gas brokerage service, Clarksons’ expert teams are able to advise and guide clients in the LPG sector. Spanning three continents and covering most time zones, our gas specialist teams work seamlessly to provide the highest level of client support with LPG shipping.