[QUOTE=injunear;120974]About 30 years ago after many workboat companies went out of business, a good friend was killed while looking to pick up some repos at a shipyard near Houma. The story I heard was he opened the liquid mud tanks for inspection. The tanks appeared to be clean but rusted. Blowers with ducts dropped into the tanks and ventilated overnight. The next day he inspected the tanks. I’m not sure of what safety equipment he had. (probably none at that time.)He had a rent-a-wino standing watch at the tank hatch. On the last of 4 tanks, there was a layer of dried liquid mud near the suction. As he broke through the top crust, H2S gas was released and he was overcome. The rent-a-wino was seen entering the tank. Someone checked a couple of hours later and found both of them dead.[/QUOTE]
Yes, that is a very dangerous situation there. Any type of solids in a tank cannot be touched without full air on. We generally use pump style gas detectors, for initial testing to get to the bottom of the tank (of course 24 hours of FORCED ventilation). We do both hatches, one that has the ladder for access, the other is the rescue hatch where the tripod and rescue equipment is set up, and has unobstructed path to the bottom with litter. Two personnel usually enter, which is policy (unless you have a visual with the attendant). We each have a gas detector on, body harness, escape breathing device, and full SCBAs are lowered on the tripod if needed. Communications with the attendant takes place once per minute.
As far as who tests the tank, we have dedicated personnel that are trained on board. The work plan is made (sec.1), permit to work started, isolation certificate made by competent person; person that is qualified to test the tank reviews the plan and isolation certificate, tank is tested - all is entered on PTW. Team then completes work plan (sec.2), PTW is given to Area Authority and OIM for final authorization. Once all paperwork is signed, rescue teams are put on notice, and bridge is notified. Entry commences. After the entry, you complete the plan, lessons learned, etc…
Competent gas detector course is 4hrs by MSA. We send each gas detector off one per year for bench calibration by the manufacture, plus the new ones also self diagnose during start-up (which we use), but we alway use up-to-date calibration gas as third check to ensure equipment is good before using.