Diesel tank reassurance

[Burning Elbows]

Hi
I have a 15000 diesel tank to mod
so far i have pumped out all the dregs that i can 450-500l odd just leaving the sludge and about 10mm in the bottom
then ive put enough water in to raise the lvl about 2" to the top of the drain plug (thats raised off the bottom *face palm*) and left the diesel to soak out of the sludge over night in the hope that in the morning i can pump it out again and almost all the diesel out

inside the tank is a spiders web of stiffeners so geting in there with a steam cleaner is out of the question

so my current plan is to jet wash all i can with a liberal splash of jizzer degreaser and then im not %100 what to do fill it with nitrogen or cougar(co2/argon) but it 35l/min it will take 7 hours odd lol , or lob in aload of water add aload of detergent n then make a inert gas bubble bath

in the past ive been able to just pass the buck n let someone else make safe but now its my job so any comments ideas or good old brain farts are welcome

 

[Drains]

Are you working inside the tank or out? The argon fill won't be any good if you're inside, and it'll need a shed load to purge that.

What you need is one o they electronic thingumies to test the atmosphere.

You knew that though, didn't you?

TBH, it doesn't matter what you do to clean the tank, you should test the air to make sure. You could spend lots of time and money either failing to clean it, or cleaning long after it's safe.

 

[Burning Elbows]

i have to weld a skirt all round the inside tank to the external tank so working outside the tank
hmmm a beeping doodad i like the cut of your jib

 

[mike os]

are you actually cutting in to the tank?

if not why not fill with water?

 

[gash metal worker]

Dont know if its the right thing to do but i sometimes run a pipe from a van exuhust into the tank and let it run for a few hours

 

[Uniqueusername]

Don't quote me or even take this as being safe practice.........
Wash out the tank with detergent and Fill with water to just above the level of welding and use a gas tester..
Filling the tank completely would be nice, but it's a lot of pressure pushing against your weld puddle (cough, cough. strange thing to account for)

 

[Weldingartisan]

I take it that you are bunding the tank? It might seem strange, but it would be safer doing a non invasive weld with the tank full of diesel - ie no oxygen, no combustion. They do hot tap (weld branches on) live high pressure gas mains within safety regs and procedures etc. W/A