Pressure testing diesel tank in RI

[Muaddib1116]

I have some sort of diesel leak in my system and I want to figure out if it's a leak in my stainless steel tank (god I hope not) or in the fuel lines. I figure the easiest way to do this is to pressure test the tank. Does anyone know who I should talk to in the RI area that really knows their stuff in this area? Thanks!

[Benz]

The guys at Newport Hydraulics can put you in touch with a guy in Tiverton who has done tank testing as well as every other funky boat thing you can imagine.

[Muaddib1116]

Are you talking about Dave and his son Nick?

[wsmurdoch]

Pressure testing the tank is not really hard. In 2018 we had a leak develop in our fuel tank while in the Bahamas. We removed the tank, cleaned it, then pressurized it with the dinghy foot pump searching for leaks with Joy detergent and water. A bit of epoxy putty in the pits, then West System epoxy and cloth over the whole bottom of the tank, and we were on our way. (Trip saved.)

This is the tank inverted on the dock with the putty spread in the corroded patches. The pump's hose is attached for re-testing to be sure we got all the leaks. The tank is tied down because it had been a bit windy.


The story is in my wife's blog https://irish-eyes-to-the-bahamas.blogspot.com/ the March 19, 2018 posting starting in the fifteenth paragraph..

[Muaddib1116]

I'm pretty sure I'd have to cut my boat apart to get my diesel tank out, and at the moment it's full of diesel. I really hope the leak is not from the tank, but I figure it should be pretty quick to put a couple pounds of pressure and observe a gauge over some period of time.

[wsmurdoch]

If it is leaking into the bilge, your first thing to do might be to get the fuel out of the tank before it makes a real mess. We have done that twice by pulling the hose off the electric fuel pump, installing a longer hose and pumping the fuel into 5 gal jugs (and in the case of the repairs mentioned above - into 1 gal water jugs). It was easy, but not terribly fast. We have also 'loaned' fuel to others on several occasions that way.

[rslifkin]

If it's actively leaking, skip the pressure test for now. Clean what you can and place oil absorbing pads and/or paper towels (taped in place if needed). That should help narrow down how the leak is finding its way to the bilge and where it's coming from.

[Muaddib1116]

It is a slow leak that I've been dealing with for a while, I thought it was from my generator that I've been trying to get serviced since I bought the boat. I was going to wait till the service was done to narrow either fix that possibility or eliminate it as a possibility, but recently there's been evidence that that was not the source.

I need to know if it's coming from the tank or from a host of other possible areas in the system. The tank leaking is a much larger problem. I don't see why I would need to empty the tank to pressure test it. It shouldn't be a very long test, and at the current rate of leak, if it is the tank, then it's not going to be much larger of a problem then it already is. If it isn't the tank, then I've saved myself a rather large amount of labor.

[Benz]

Originally Posted by Muaddib1116

Are you talking about Dave and his son Nick?

Yeah. Do you know them?

[boatpoker]

I've seen pressure testing metal tanks with "suspected" leaks turn them into tanks with "significant" leaks. Don't do it onboard with fuel in the tank.

[Muaddib1116]

Originally Posted by Benz

Yeah. Do you know them?

Yeah, they're great guys. I've had them do some stainless welding and they rebuilt my bowthruster motor and serviced the gearbox last spring. I'm having them do some more welding this winter and some hydraulic stuff for my navtec system. I'll talk to them about this and see what they say. Thanks.

[Bowdrie]

Originally Posted by boatpoker

I've seen pressure testing metal tanks with "suspected" leaks turn them into tanks with "significant" leaks. Don't do it onboard with fuel in the tank.

Sage advice.
In general, stainless steel has a checkered history for diesel tanks.
It's not the base metal, it's the welds.

[rslifkin]

Originally Posted by boatpoker

I've seen pressure testing metal tanks with "suspected" leaks turn them into tanks with "significant" leaks. Don't do it onboard with fuel in the tank.

I was thinking the same. If there's an issue with the tank, depending on what's failing, adding pressure might make things get significantly worse.