PCTFE Cryogenic Seals for LNG Loading Arms

Transporting Liquefied natural gas (LNG) is a major challenge because it must be done at cryogenic temperatures.

Any ship which loads liquid cargo in bulk must have a proper loading arrangement, some use flexible rubber hoses or reinforced composite hoses; however, some terminals have loading arms for chemicals and clean products.

The main reason for using loading arms is their flexibility in accommodating any movement of the vessel during loading or discharging.

A key part in the design of the loading arm is the swivel joint which makes the loading arm flexible. The swivel joints are made of stainless steel, the dynamic seals used are made of polymers, large-diameter seals are used at the joints and connections.

LNG is transported at close to atmospheric pressure chilled to -260 deg F. At this temperature, the gas becomes a liquid making it far more cost-effective to move. The downside of this is that the seals are very susceptible to failure due to the extreme environment.

Cryogenic sealing involving liquid nitrogen can be quite challenging, but certainly not impossible thanks to materials such as PCTFE that offer good thermal stability, good chemical resistance, very good physical properties.

One of the major challenges is the fact that cryogenic liquids are poor lubricators. Because of the risk of freezing and causing the system to lock up and experience catastrophic damage.

How do the PCTFE cryogenic seals overcome these challenges?

• Dimensional stability through a wide temperature range
• Low friction and high wear resistance
• Rapid recovery after the load removal
• Toughness and strength in accordance with the application
• Low thermal expansion to prevent thermal contradiction with adjacent metallic components
• The capability to operate and maintain its elasticity at extremely low temperatures
• High wear resistance
• Low friction

To find out how we can help your latest project please contact info@fluorocarbon.co.uk.