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Re: [PSUBS-MAILIST] Re: Mig welding a sub
Ian,
I'm going to annotate your post with my replies
in red
James Long
Owner/Designer
Lil Brother LLC
(Instrument Division)
----- Original Message -----
Sent: Wednesday, July 25, 2007 4:25 PM
Subject: Re: [PSUBS-MAILIST] Re: Mig welding a
sub
Ah, I think understand what you are talking
about. Your talking
about not needing the same inspection/process for
creating 200feet
operational depth sub vs creating a 1000feet operational
depth sub?
Apologies if I'm not reading your emails correctly.
Yes....that is why I'm trying
to say, that the construction is critical, but not as such as a deeper depth
rating. It's ok, I some times do not construct my emails correctly to relay the
message I'm trying to get across. Hopefully I'll do better with my sub.
:-)
If you take into account safety factors, then the two hulls
can
come out similar. Also, if you are skimping on inspection, then
over
engineering isn't a bad idea (i.e. using a material thicker
compared to the
relative operation depth than a full inspected
sub would use compared to it's
operation depth).
I tend to agree, to a point. I don't see it as skimping
on inspection. You can test some welds before actually building the sub. I just
don't know if I would x-ray every pressure hull weld. That would be a huge
expense. There are problems associated with over engineering also. If the
pressure hull gets to a point of penetration problems, you can end up with a
bigger problem than lack of inspection.
For safety factors, I'm
think of the time for action after you
cross your operational depth (due to
some sort of problem). With
a 25% safety factor in 1000foot operation
depth sub, you have the
time taken to travel 250feet to react to the
problem. But in a
200foot operation depth sub, 25% only gives you
50feet to react,
if you want to same amount of time to react, you need a 150%
safety
factor. So combine the safety factor with some over
engineering
since you are not full inspecting/x-raying the welds, and you
end
up with similar pressure hulls.
This is an operational problem.....not a safety
factor problem. I would never take a sub to a location
(submerged) that would exceed the maximum design rating (with ofcourse
safety built in). This is a standard safety area. If you can't exceed the
submersible depth, nothing can go wrong. If you operate a sub submerged
with a pressure rating of 250 ft. in 500 ft. waters you are asking for disaster.
My take on this, if you are building a sub with a max depth of 250 ft. the
theoretical crush depth should be 500 ft. but I would never operate it in waters
over 250 ft. submerged.
I know some one is going to say that is
impossible......I didn't say I would never operate the sub in 500 ft.
waters, I just would never dive in 500 ft water. If the sub starts to sink while
in transit (the passage through water deeper than 250 ft.) I would get out,
because I'll be on the surface.
But we should consider, I probably wouldn't have my
welds tested by x-ray. I'm just not going to that length. I don't knock anyone
who does, I just don't see it necessary for me to have piece of mind.
At least this would be my (current) thinking/approach.
I believe we are in agreement.
I tend to do things my way, and so far (with all the
things I've done) it hasn't failed me yet. I hope (while knocking on wood) I do
not become a statistic that someone reads about.
James
-----Original Message-----
>From: Lil Brother LLC <
lil_brother_llc@bellsouth.net>
>Sent: Jul 25, 2007 4:22 PM
>To: personal_submersibles@psubs.org>Subject: Re: [PSUBS-MAILIST] Re: Mig welding a
sub
>
>Ian,
>
>There wouldn't be a difference, if you
are brave enough to use a thin
>material to go to 1000 ft. It would be a
waste to use a 1000 ft. material
>(thickness wise) to only go to 200
ft.
>
>The equipment necessary to weld (properly) a hull 1/2 inch
thick can easily
>weld a hull 3/16 think, but the opposite is not
true.
>
>I'm not just discussing the seam, but the equipment,
diligence, and
>inspection required for the seam to be proper. It is more
difficult to weld
>a 1/2 piece of material proper than a 3/16
piece.
>
>James Long
>Owner/Designer
>Lil Brother LLC
(Instrument Division)
>----- Original Message -----
>From: "irox"
<irox@ix.netcom.com>
>To:
<personal_submersibles@psubs.org>
>Sent: Wednesday, July 25, 2007 2:51 PM
>Subject: Re:
[PSUBS-MAILIST] Re: Mig welding a sub
>
>
>
>Then, what
is the difference between a seam welded for a
>200feet dive depth and
1000feet dive depth for the same
>thickness material?
>
>I
don't think there is a
difference.
>
>Ian.
>
>-----Original
Message-----
>>From: Lil Brother LLC <lil_brother_llc@bellsouth.net>
>>Sent: Jul 25, 2007 3:16 PM
>>To: personal_submersibles@psubs.org>>Subject: Re: [PSUBS-MAILIST] Re: Mig welding a
sub
>>
>>Ian,
>>
>>As I understand it...the
material thickness plays a major part of the
>>welding process. The
thickness makes a major difference.
>>
>>James
Long
>>Owner/Designer
>>Lil Brother LLC (Instrument
Division)
>>----- Original Message -----
>>From: "irox"
<irox@ix.netcom.com>
>>To:
<personal_submersibles@psubs.org>
>>Sent: Wednesday, July 25, 2007 2:05
PM
>>Subject: Re: [PSUBS-MAILIST] Re: Mig welding a
sub
>>
>>
>>
>>What's the difference between
the seams? From what I've read there
>>would be no difference
other than the matterial/thicknesses
being
>>connected.
>>
>>Ian.
>>
>>-----Original
Message-----
>>>From: Lil Brother LLC <lil_brother_llc@bellsouth.net>
>>>Sent: Jul 25, 2007 2:21 PM
>>>To:
personal_submersibles@psubs.org>>>Subject: Re: [PSUBS-MAILIST] Re: Mig welding a
sub
>>>
>>>Dan,
>>>
>>>I somehow
missed this message.....
>>>
>>>I have a
question........Wouldn't submerged series arc be the best
method
>>>to seal a pressure vessel? It's totally one bead, has
similar penetration
>>>to stick, and is easily
controlled.
>>>
>>>Although I'm not sure who would have
a rig that could weld a round vessel,
>>>I'm sure it could be
done.
>>>
>>>I agree a backhoe bucket weld wouldn't do
the trick, but also on the other
>>>hand the seam to seal a vessel
designed to go 1000 feet, is not the same
>>>seam as a vessel only
designed to go to 200. The variables are
totally
>>>different.
>>>
>>>James
Long
>>>Owner/Designer
>>>Lil Brother LLC (Instrument
Division)
>>> ----- Original Message -----
>>> From: james kocourek
>>> To: personal_submersibles@psubs.org>>> Sent: Wednesday, July 25, 2007 5:51
AM
>>> Subject: Re: [PSUBS-MAILIST] Re: Mig welding a
sub
>>>
>>>
>>> Hi
Dan,
>>> I appreciate your input. I have done failure testing
prior to welding on
>>> my sub with exceptional success. I think
that some of the time flux core
>>> gets a bad rap because of the
fact that the little buzz boxes use flux
>>> core. Mine is a 350 amp
mig computer controlled pulse welder as speced by
>>> both lincoln
tech specialists and my coach, an extremely experienced and
>>>
active pressure vessel welder.
>>>
>>> I concure
that one cannot be too cautious.
>>>
>>> I am
interested in talking with you more at the convention about this
>>>
subject and appreciate your feedback.
>>>
>>> Rest
assured that I did considerable homework prior to choosing the
>>>
method that I am using now.
>>>
>>> Thanks again
& Best Regards,
>>>
>>> Jim
Kocourek
>>> ----- Original Message -----
>>> From: Daniel
Lance
>>> To: personal_submersibles@psubs.org>>> Sent: Tuesday, July 24, 2007 7:50
PM
>>> Subject: [PSUBS-MAILIST] Re: Mig welding a
sub
>>>
>>>
>>>
>>>
James
>>> I believe it would be in your best
interest to strive for the highest
>>> possible weld integrity
for the pressure hull of your submarine. A weld
>>> procedure that
is acceptable for a backhoe bucket isn't necessarily
>>> adequate
for Pressure Vessel Quality work. Typical Quality Control
>>>
standards for PVQ require full penetration X-ray quality welds to
acheive
>>> 100 % of the strength required for such a demanding
applicaton. While
>>> there are many welding processes available to
the average person, ( mig,
>>> tig, stick). Some are better suited
than others in a given situation
>>> depending on a particular
individuals skill and experience level. As an
>>> example , I
have seen "side bend" Mig weld tests performed by highly
>>>
skilled welders with ten's of thousands of hours of welding
experience
>>> split apart in the weld bead zone. Mig has a tendency
to exhibit very
>>> shallow penetration in certain circumstances.
The trick is to know WHA! T
>>> circumstances. If you are going to
perform your own welding I!
>> would recommend that you do what
industry does. Take a weldor
>>qualification test in the weld process
and welding procedure you intend to
>>implement in your build project.
Get a copy of "The Procedure Handbook of
>>Arc Welding" by the
Lincoln Electric Co. of Cleveland Ohio. This an
>>excellent reference
book with a chapter devoted to weldor qualification
>>tests. If you
have a hydraulic press in your shop you can perform your
own
>>tests. If you plan to hire someone to do the welding for
you insist that
>>they pass an approved test administered by a
qualified laboratory. Rework
>>is expensive , do it right the first
time. And of course,......what is your
>>life worth?....... someone who
says they can do it or someone who can prove
>>that they can do
it.
>>> Happy sub
building,
>>>
>>> Daniel
Lance
>>> lanceind@earthlink.net>>>
>>>
>>
>>
>>
>>
>>
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