welding on a hydraulic reservoir

By jer

Date 03-31-2005 20:32

The unit has a crack in it, I was told its made of cast iron which I do weld a lot of. The issue I have is that it was filled with hydraulic oil. If drained and I prepare weld area what concerns of explosion or fire could I have with this ?

Typically I drill holes at ends of crack and groove out crack. I then pre heat to around 600 degrees, although the unit may or may not fit in my oven and may have to be heated with rosebud on torch.

I like using stick with Nyrod 99.

By - Date 03-31-2005 20:48

One thing you can do is fill the tank with water unless the crack is all the way through and will leak if filled with water. Just draining the fluid will not get all the fluid out of the intergranular structure of the tank. If you can position the tank where the crack is right on top and you can fill it with water up to the crack, that would probably be the safest way to go. If you have a way to high pressure steam clean the tank, that is another option.
Cast iron has a propensity to cracking, so I would recommend you drill your holes 1" past the ends of the crack. Your preheat and choice of filler metal is good. After welding you should make sure the weld zone cools down very slowly by maybe wrapping it in fire blanket until ambient temperature is reached. Since you weld cast iron a lot, you already know what it takes to make a successful weld.

CM

By pjseaman (**)

Date 04-01-2005 00:56

I agree with cmeadows and you know how Ni99 rod flows so the only thing to add is taht acetone will help remove the contaminants from the surface and prep area. You may also have to butter and grind the area several times to get out all the contamination.

Good luck, hydraulic oil is a pain to get out of cast.

By - Date 04-01-2005 01:17

PJseaman makes very good points. The secret is to start out with a clean surface. If your preheat and grinding does not get out the contaminents, several welding cycles (heat thermal cycles) might be required. Good luck and don't blow yourself up !!!

Chuck

By SA-200

Date 04-02-2005 13:28

You can steam clean the outside and inside of your tank. When cleaning the inside just be sure the tank is inverted so the contaminants will run out as you are spraying the inside. Dont be in a hurry, take your time.

By jer

Date 04-04-2005 00:48

Thanks for the feed back guys. So this could be an explosive situation ? and or a flammable one.

By billvanderhoof (****)

Date 04-05-2005 06:51

Even paint on the interior of a tank can volitilize and become potentially explosive. On the other hand if the tank fits in your oven I believe that most hydraulic oils will evaporate below 600 degrees. Synthetics may not. In addition to careful cleaning I like to continuously ventilate anything that I think may generate flamable fumes while I weld on it.
Bill