I am now a retired Marine surveyor. my specialty or should I say the nature of my business was the on hire and off hire of barges and derrick barges & trip surveys of unclassed barges. i have done well over 500 entries during my 40 year tenure.
I had my own O2 equipment and for the most part did my own gas freeing of compartments safe for entry. the unit came with 20 ft of hose and a pump. while below the monitor would run all the time. as i typically worked alone. It was SOP to have a spotter or safety man on deck who would yell down periodically to see that I was OK.
you have to walk the interior all tanks to their farthest bulkhead prior to the start of recording information for the survey
the fact that I had my own sniffer which I tested prior to entry and was serviced or replaced as needed saved my life on numerous occasions when vessel owners or charters were anxious to get there charter started so that they could use the barge. Lying to me that the barge was safe was not uncommon with certain companies that did not remove the hatch covers 24 hours prior to my attendance. and costly to them because i would refuse to enter.
in these cases time was consumed in power ventilation some times overnight of all compartments prior to entry and continued during the survey time within the tank.
barges without interior coating and with heavy build up of rust are a particular hazard as the rusting process consumes air.
The USCG required a Marine chemist certificate before their inspection as it was necessary say in the case of an unclassed barge to get a trip permit for off shore transit. it was all coordinated by me and i made sure prior to the chemist arrival that i had sniffed all tanks.
having your own equipment is essential. i also had a monitor with alarm tied to my shoe lace so as you went down the ladder the shoe unit would pick up any hazards first.
shipyards i worked with sniffed the tanks at least twice a day usually during the lunch break if there was hot work being done in the tank which can alter the concentration of air in the compartment. certificates were usually posted at each tank entry with date and time.
some people dont realize that you will be dead in an instant from entering a tank that has not been gas free
I have been class surveyor for over 20 years and am still amazed at how often ships fail to follow enclosed space requirements.
Plenty of time I’ve had to refuse to enter as the tanks were clearly not checked, checked with expired/uncalibrated meters and otherwise not ventilated.
You’d be amazed how many times I get to a vessel and I’m greeted with “these tanks are fine they’ve been open for weeks you’re just here as a formality” and then I proceed to find oxygen levels below the required minimum to sustain life……
Being a marine chemist is one more of the toughest jobs in the marine industry. You have the lives of others in your hands . Most retire early those steel decks and ladders take a toll on knees and hips
When I started surveying in the late 70’s. It was not unusual to loose a couple of surveyors a year to confined space and lack of oxygen
Some just stand above the tank hatch looking down and over come by fumes
Ventilation was not used except for explosive atmospheres and almost exclusively at the shipyard.
Not to make light of this serious topic. But the first guy in was called the canary
Sensing equipment was extremely expensive back in the day and rare except with the large companies and ship yards
Actual canaries might have been a good investment back then or maybe a mine safety lantern.
Low flame or flame goes out = low oxygen
Normal = normal
Bright flame = flammable/explosive gas
Ship blows up = defective lantern
In all my time at sea on tankers and chemical tankers there is no doubt the most dangerous thing we do is tank entry. And that is on our own ship, with our own people. I can’t imaging walking onto a ship/barge that I didn’t clean, blow and test myself and entering a tank.
I was in tankers in the early 70’s with crude oil washing and exhaust gas inert systems.We had a set routine for entering tanks. Wash, purge with inert gas monitoring exhausting gas for explosive limit, introduce atmospheric air with Golar vent fan continuing monitoring, if explosive lower limit increases return to purging. Venting continued until oxygen level at atmospheric level. Then entry with trolley set to use oxygen sampling in corners. We had all test equipment and spare parts.
The job of a marine chemist is physically demanding. I have seen marine chemists come out of the tanks huffing and puffing and dripping with sweat on a hot day in the U.S. Gulf and elsewhere. But the truly dangerous moment is the initial entry after washing, purging with I.G. and re-introducing fresh air into the tank. The measurements are taken with a calibrated meter by the Chief Mate and he/she then enters the tank with the meter and takes a perimeter walk around the tank and exits hopefully declaring the tank safe for entry.
By the time a marine chemist looks at the tank on a properly managed tank ship (barges are usually a different story) the tanks have been inspected multiple times and depending on the work to be done ship’s personnel have been down in the tanks cleaning or making necessary repairs for days if not weeks before the marine chemist arrives. The marine chemist provides a valued safety check to protect shore personnel, but the difficult and precise work of cleaning up the ship to the standard of: “Safe for entry, safe for work”, has been done by the crew under the supervision of the Chief Mate.
You tanker guys are funny
When they were developing prudoe bay
We moved modules off the barge by grounding the barge and building a berm to use as an off load ramp. The lashing were steel pipe with slotted flat plate on each end
Before hot work commenced to burn off the lashing we used carbon monoxide from the bulldozer to inert gas the tanks
Unorthodox but it works. Off hire was back in the 48s. So no problem once your back in civilization
An old case: Man was cutting an access hole into the top of a fuel tank that had just been butterworthed, certified, etc.
Bunker C came bubbling through the hole. Sorry, wrong tank.
Lucky it was completely full or the explosion from gases would have been tremendous.
Welding tanks from the outside <> confined space entry, but it too involves checking the tanks (or not). Someone died just down the road from me welding on a fuel tank that they thought was inert, it wasn’t, and it blew up.
My experience with un inspected barge and one way trip permits is they will not enter a barge without a chemist certificate no matter if I told them I sniffed and entered earlier
Certificate was good for all day 12 hrs typically
However these were primarily deck barges
I have never seen anything in the CFRs regarding entry Typically the COTP sets the policy at the district level