Arteinis if you are on about me 'have tried ledge above which has air duct above ,jumped on that andfollewed it pass the steam coming from pipes doe'snt seem to lead any where .What do i have to do before i can open door.

carry on going up. if this is the map that i think it is, you should see a locked lift shaft, and a ledge above it, jump on the ledge, and there should be a pipe with steam coming out every so often, get on that then do a crouch jump , and work your way up. i think there a 3 (maybe 4) columns with steam coming out, only on 1 of them can u make it too the upper bit.

oh and i hope you saved your spears cos they will come in handy