LNG and LPG are actually different things LPG is carried at 9 bar and -30 centigrade with a insulated tank and a reliquification plant for boil off. LNG is carried at -186 centgrade and atmospheric pressure in a super insulated tank with no reliquification lant and the boil off used to produce steam and power the ship with a steam turbine.

LNG is fun in two ways 1 cubic meter of liquid makes about 600 cubic meters of gas and 1 cubic meter of gas makes about 600 cubic meters of explosive gas and we carry about 100,000 cubic meters of liquid so you have a huge potential for a bang.

the other fun factor is that if you spill liquid cargo on the hull the steel freezes and the hull shatters terminator 2 style.