Ok i think i know what bit your talking about.
If you go into the room that goes on fire and go out the bit where the cargo ship comes in and look down into the green water you'll notice that every so often a pipe comes out to release the fire from the room after it's been fired up. There's a ledge there that you can jump down to then basically you have to run in the pipe just after it releases a burst of fire and destroy the thing in there, the det pack things work well here. If this works the room won't go on fire anymore and u can jump on the cargo ship using the pillers to get to the next area.
Hopefully you can make some sense of that
