Scotch marine boilers eh, tube stopper job? Remember? Shut down leaky furnace, steam on two until alongside or on the hook, shut down the other two fires, allow to cool, out with the ice buckets with spanners in it, open the furnace door, blast of heat, strip, ice cold overhauls and in you go. No mention of claustrophobia here or hide it to show you are not a woosy. Haul yourself across all those corrugations, miles and miles of it til you reach the other end of the boiler tube stack face. Stand upright, carbide light in hand, locate leaky tube/s, out with the plugs, taper hammer in or taper expansion screwed expander type, really got a sweat on now twofold, air temp and whether some wag is going to shut the furnace door on you, seen it done several times. Allways shouts of, oh look, someone's left the furnace door open, better close it. At least if you had a lead light in use they could not close and lock off the door on you. Back out,flash up and test. No more than ten per cent of the total tubes to be done but many ships had nearer twenty per cent stopped up. Plugging the other end was nowhere near so scary. I also remember the boiler blow off relief valve settings, part of the refit would be entail stripping the valve to expose both seat faces. If bad, let go all pipe work and crane valve assembly off the ship and back to the workshops, into a lathe, set it up concentrically and carefully cut the seat in the housing. Recut the the actual valve itself in a three jaw self centring chuck, then coarse, medium, fine grinding and reassemble and back to the ship. Now with a full head of steam the relief pressure blow off had to be reset, another scary job. Someone in the boiler room watching the psi gauge shouting to others in the chain, ( no r/t here ) " on the blood " when the gauge reached the red sector of the gauge and the charge hand would wind the big spring loaded adjuster up or down as the case may be. Loads of steam here. Reckon you could still do the firebox furnace run? Probably be more scary now than then.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.