Electrolysis Tank Cleaning

[Friartuck]

Folks,

Thought this was important enough to make a separate posting. The topic of Electrolyisys rust removal has been well documented, but this method was with a twist. The project was a 1920's gas tank that was taken to a national chain for professional cleaning & refurbishment. They cut it open and discovered (learned) that it had seperate compartments in the bottom for the switchable 2 gallon reserve. They returned it to the customer in peices that they could not apply their process and guarantee it. So now the customer is worse off than he started; a rusty tank that now has to be welded back together. The goal here was to perfect a procedure to prevent this from happening again (invade a perfectly good tank just for the sake of cleaning it).

The tank is treated as the cathode (negative lead) and a one foot long peice of concrete reinforcing rebar Anode (positive) has heavy 10 gauge wire soldered to the tip and connected to the positive lead of the battery charger. The tips of the rebar are insulated to leave it high enough off the bottom and not short out against the metal walls of the tank. The solution is sodium carbonate (Ph level additive or Arm&Hammer washing soda (not baking soda). Leaving the Rebar in for about 2 hours will collect the rust from the tank's inner walls. If your battery charger has a meter, you'll notice the current will decrease and the rust deposits on the rebar begin to prevent the current flow, hence an indicator of when to clean off the rebar. 5-7 amps is a clean anode and reduced to 1 amp means a dirty anode (needs cleaning). The test sheet metal picture shows the effect (after about 4 hours) noting the submersion line. The electrolysis also attacks some of the old gas residue, an unexpected benefit. I expect this tank to require several days of cleaning, but I think that is a small price to pay. In a closed tank, you may have to delicatly route the rebar to prevent shorting. I hope his helps someone else who has a rusty tank that needs cleaning and hopefully avoid having it needlessly cut open. The plan here for this tank (after welded and pressure tested) is to use a slooshing sealer after the tank is bone dry.

The below pics show the rebar with and without the rust deposits.

WARNING: Electrolysis gives off Hydrogen gas: No open flame, sparks from the alligator leads and no smoking while in progress.

Edited April 14, 2013 by Friartuck (see edit history)

[Jim Bollman]

Neat application of electrolysis cleaning. I have been a fan for a lot of years and have several different size tanks I use when I need to clean up parts but never thought about making the part the tank.