Never heard of this practice, however, on some cargoes it was common
practice to start loading by gravity only (slow) until the suction bells
were covered to avoid splashing, for much the same reason.
On todays ships, most use inert gas in the tanks to keep the oxygen level
too low for combustion.



Vic Smith wrote in
:


When I was watertending on Great Lake tankers deck hands would toss
some hundreds of pounds of dry ice in the empty tanks before we
refilled. Supposedly suppressed the generation of static electricity.
I preferred to be ashore. Do they still do that?

--Vic

On Tue, 17 Jul 2007 15:58:26 GMT, otnmbrd
wrote:

Never heard of this practice, however, on some cargoes it was common
practice to start loading by gravity only (slow) until the suction bells
were covered to avoid splashing, for much the same reason.
On todays ships, most use inert gas in the tanks to keep the oxygen level
too low for combustion.

After searching around a bit, it seems the purpose of the dry ice was
to inert the tank. My recollection of looking down into the tank was
there wasn't enough CO2 coming from the blocks to do it, but I didn't
stay around long.
I also found that a number of people have been killed by exploding
tanks when attempting to inert a tank using a CO2 bottle.
The discharge from the bottle itself can generate enough static to
produce a spark before the tank atmosphere becomes non-explosive.
Like they say, a little knowledge can be dangerous.
Never did like sitting on a bomb myself.

--Vic

Vic Smith wrote in
It's been awhile, but some tankers didn't use IG due to possible
contamination of cargo.....either the possible soot could do it or would
change coloration of the cargo itself.
At any rate we all breathed easier with IG. One time as a test we Crude
washed a tank then gas free'd it after which I went down to do some
repairs..... found a few "hot spots" but finished repairs and decided it
wasn't a good idea....i.e., it worked but "no thank you".




:

On Tue, 17 Jul 2007 15:58:26 GMT, otnmbrd
wrote:

Never heard of this practice, however, on some cargoes it was common
practice to start loading by gravity only (slow) until the suction
bells were covered to avoid splashing, for much the same reason.
On todays ships, most use inert gas in the tanks to keep the oxygen
level too low for combustion.

After searching around a bit, it seems the purpose of the dry ice was
to inert the tank. My recollection of looking down into the tank was
there wasn't enough CO2 coming from the blocks to do it, but I didn't
stay around long.
I also found that a number of people have been killed by exploding
tanks when attempting to inert a tank using a CO2 bottle.
The discharge from the bottle itself can generate enough static to
produce a spark before the tank atmosphere becomes non-explosive.
Like they say, a little knowledge can be dangerous.
Never did like sitting on a bomb myself.

--Vic