Welding Around Fuel Tank

Mods and custom builds
Maineiac
Posts: 4
Joined: Mon Jun 29, 2020 8:35 am

Welding Around Fuel Tank

#1

Post by Maineiac »

I have a few repairs/modifications that I need to do around the deck of my pacific skiff, which has a below deck fuel tank. Although I’m familiar with the hazards of gasoline vapors, I’m unsure of how to go about welding on the deck safely. Do you guys just pump the below deck space full of some type of inert gas? C02, nitrogen, car exhaust? Just pull the trigger and pray? Tell me the right way, the shade tree way, and the wrong way.

Seth

User avatar
gandrfab
Posts: 510
Joined: Fri Mar 28, 2008 12:33 pm
Location: Edgewater Fl

Re: Welding Around Fuel Tank

#2

Post by gandrfab »

Remove all combustibles, happily weld clean metal. Possibly fill with argon.

Ventilate, circulate, positive air flow taking any fumes away.

1/4 full fuel tank, pressurize tank wait till you smell fumes and (make yourself right with Jesus) then strike an arc.

kmorin
Donator 08, 09, 10, 11, 12, 13, 14 15, 16 17, 18, 19, 20
Posts: 1530
Joined: Mon Aug 18, 2008 1:37 am
Location: Kenai, Alaska

Re: Welding Around Fuel Tank

#3

Post by kmorin »

Maineiac,
I don't mean to be hard to live with, in my reply. I'm not being smart a$$ed, rude or condescending.

I've worked around welded aluminum boats, gas tanks and repairs for a long time, and have a "trophy" on here somewhere to show for it.

So, after asking the question, I'll reply : "IF you have to ask- you're probably not qualified to do that"

Again, I'm NOT aware of your knowledge, skills, welding methods or experience; just doesn't sound like it's something you should do- IMO. Hope your project works out safely to a well thought out ending.

Cheers
Kevin Morin
Kenai, AK
kmorin

Maineiac
Posts: 4
Joined: Mon Jun 29, 2020 8:35 am

Re: Welding Around Fuel Tank

#4

Post by Maineiac »

kmorin wrote:
Tue Jul 28, 2020 11:24 am
Maineiac,
I don't mean to be hard to live with, in my reply. I'm not being smart a$$ed, rude or condescending.

I've worked around welded aluminum boats, gas tanks and repairs for a long time, and have a "trophy" on here somewhere to show for it.

So, after asking the question, I'll reply : "IF you have to ask- you're probably not qualified to do that"

Again, I'm NOT aware of your knowledge, skills, welding methods or experience; just doesn't sound like it's something you should do- IMO. Hope your project works out safely to a well thought out ending.

Cheers
Kevin Morin
Kenai, AK
Kevin,

I’m hoping that I just hit a safety nerve. I appreciate your honest answer, although I would say I’m fairly surprised by it. I’ve seen threads on this forum where an individual has stated their complete ignorance, and you have kindly responded with a wealth of knowledge.
I feel I have adequate skill and tools to complete the repairs and modifications, IF I didn’t think the fuel vapors were an issue. I don’t have the equipment that professional, or former professional boatbuilders have, but I do own a 220v MIG welder with a spool gun, as well as a TIG setup.
I’m a tugboat operator by profession, and all I move are gasoline barges. I’m aware of the hazards, thus my query to the forum.

Thanks,

Seth

kmorin
Donator 08, 09, 10, 11, 12, 13, 14 15, 16 17, 18, 19, 20
Posts: 1530
Joined: Mon Aug 18, 2008 1:37 am
Location: Kenai, Alaska

Re: Welding Around Fuel Tank

#5

Post by kmorin »

maineac, yes my safety sense was kind of alerted. While I have answered in great detail for many projects.... not that many involved built in gas tanks!!

Problem is: you should remove the tank to do the work. BUT removing the tank will increase scope of work "off the charts." Have you looked up Jettywolf's Pacific tank replacement thread, here?

That post is enough to scare me- given that Pacific didn't address the issues implied by the tank failure- not saying your tank is failing like his did, just a caution.

Next is: talking about having vapors in the bilge void- under deck volume - that shouldn't be possible or even remotely possible as it indicates the tank or fittings are having some problem and if so.... I don't see how you'd ever seriously and safely make that volume inert if there is a leak; liquid or vapor in the bilge.

Next is: unless the tank fill, vent and draw are all welded pipe (highly unlikely) then there's a "rubber/elastomer" deterioration potential that may not even register unless you use an LEL (lower explosive limit) meter of good quality- and even then....
(Next is ) the location of the work in relation to the tank may mean that it's not reasonable (IMO) to take a chance on lighting up near a tank.

IF you could flood the tank? that would be safe but then cleaning it out to use it again is a major project- and one that would make the deck work probably seem simple?
IF you could seal the tank completely? Then you might have a shot at the work.

Not knowing more? I'd still recommend on the side of safety: Just don't do it.
But happy to suggest lots of ways to do the modifications, and even provide details?

Image

Great white hunter with his trophy, killed up close and personal using TIG torch!

Cheers,
Kevin Morin
Kenai, AK
kmorin

Craigb
Posts: 4
Joined: Sun Sep 15, 2019 10:49 am

Re: Welding Around Fuel Tank

#6

Post by Craigb »

These boats have the tank installed under a sole that is fully welded in, and no 'soft patch' is available for tank inspection or removal?

kmorin
Donator 08, 09, 10, 11, 12, 13, 14 15, 16 17, 18, 19, 20
Posts: 1530
Joined: Mon Aug 18, 2008 1:37 am
Location: Kenai, Alaska

Re: Welding Around Fuel Tank

#7

Post by kmorin »

Craigb,
while not intimate with the construction of all the Pacific Skiff models, the boats I've seen (on here) with welded in/integral tanks seem to be built with the tank top as part of the deck? So the top is welded to the tanks' sides with an overhanging lip/flange that is then welded to the surrounding deck beams as supports? Not having super detailed photos of any deck or tank work sort of limits that idea- on my part- to speculation!

It should be noted that welding in the tanks, and having the tank top as part of the deck or cabin sole is not new or shown to be much of a problem in the past. Lots of builders do this and on ALL those boats, a saw is needed to remove the tank(s). What really gets in the way is when a console or cabin are placed over this area of construction and welded down!! Now to fiddle with the tank you'd have to remove more than just some deck!!

My description of the boat may not be accurate? There may be instances where a second/separate deck is built over the tank? And I think there's at least one set of pics- recent post on this Forum- where the tank was plastic- contained in a dedicated tank void beneath the deck. That is how Jetty Wolf rebuilt his boat's tank- he put a plastic tank in to replace a previously failed aluminum tank.

But, it is my understanding, in general that this builder generally welds tanks in- regardless if the tank top is deck or a deck is over the tank- & that a saw is needed to get at the tank for removal/repair/replacement? At least that was the case in Jetty Wolf's post about his tank replacement.

Not sure in Maineiac's boat, exactly how it's built? However, its pretty clear that removing the tank (s?) is something he'd like to avoid!!

Hope this helps with my assumptions (none of which are more than guesses from what little I know?) so not to be considered fact until there's confirmation by Maineiac or someone else with knowledge of the construction of the Pacific Skiff design and build details ??

Cheers,
Kevin Morin
Kenai, AK
kmorin

MacCTD
Posts: 547
Joined: Tue Jul 22, 2008 2:53 pm
Location: MA

Re: Welding Around Fuel Tank

#8

Post by MacCTD »

If Mainiac's Pacific is pre 2005 it probably has a plastic tank
'05 Pacific 1925
Mercury 150

kmorin
Donator 08, 09, 10, 11, 12, 13, 14 15, 16 17, 18, 19, 20
Posts: 1530
Joined: Mon Aug 18, 2008 1:37 am
Location: Kenai, Alaska

Re: Welding Around Fuel Tank

#9

Post by kmorin »

Maine', Mac,
if the skiff has a plastic tank- and the vapor question can be completely controlled/contained/sealed off.... then the insulation of the plastic holding the fuel away from and ignition source eliminates the potential for stray arc in a metal enclosure igniting the fuel.

IF this boat has a plastic tank- AND that can be sealed? Then welding even next to the tank is manageable: when compared to a built in aluminum tank.

Be interesting to hear what Maineiac decides?

Cheers,
Kevin Morin
Kenai, AK
kmorin

Maineiac
Posts: 4
Joined: Mon Jun 29, 2020 8:35 am

Re: Welding Around Fuel Tank

#10

Post by Maineiac »

Unfortunately (or fortunately) its an aluminum tank.

Post Reply Previous topicNext topic