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Re: [PSUBS-MAILIST] Welding Revisited
Joe,
Ok....I'll change my answer to this.......it is possible to survive a
depressurization at 200 feet, but very unlikely. At 900 feet we all know you
won't, not a chance.( maybe by miracle)
Also.....why go to 900 feet. There is little down there to see. If you are
looking at something down there....you probably shouldn't be. I mean if you
are poking around a shipwreck, that is a dangerous place for a submersible.
Maybe research or something.....but a personal sub...come on. I think I
would like to stay in the realm of regular scuba. If something does go
wrong....at least I have a chance, even if it is a small one.
James Long
Owner/Designer
Lil Brother LLC (Instrument Division)
----- Original Message -----
From: "Joseph Perkel" <joeperkel@hotmail.com>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, July 25, 2007 10:23 PM
Subject: Re: [PSUBS-MAILIST] Welding Revisited
".............The statistics would say that you are mistaken. The human body
(if not
crushed) would be far more likely to survive the pressurization(even
rapidly) at 200 feet,........."
Careful there James. That statement makes me wonder about your appreciation
for dive physiology.
Big "D" lies at 235' and continues to take it's toll on people who prepare
like this..
http://www.mikey.net/scuba/pics/andrea_doria_july_2001/tami_night_dive.jpg
Joe
>From: "Lil Brother LLC" <lil_brother_llc@bellsouth.net>
>Reply-To: personal_submersibles@psubs.org
>To: <personal_submersibles@psubs.org>
>Subject: Re: [PSUBS-MAILIST] Welding Revisited
>Date: Wed, 25 Jul 2007 21:03:23 -0500
>
>Dan,
>
>You said the magic words:
>
>"Most psubers won't spend the money to x-ray
>their welds , but would'nt you like to know they would pass a test if you
>did one ?"
>
>I don't care who the person is, how good they are, there is a possibility
>of
>the weld failing x-ray inspection. If that were not the case, the U. S.
>Navy
>wouldn't x-ray every weld on a sub.
>
>Just because a highly qualified welder is diligent and does his best, does
>not mean he will not make a mistake. He is human after all.
>
>You couldn't actually tell if the weld would pass an x-ray unless it is
>actually performed. Granted the welder will be very careful about his work,
>a third person is always less concerned with your safety than you are. This
>is just a fact of human nature.
>
>"If your hull fails at 200 hundred feet you will be just as dead
>as if it failed at 900 feet."
>
>The statistics would say that you are mistaken. The human body (if not
>crushed) would be far more likely to survive the pressurization(even
>rapidly) at 200 feet, but is extremely unlikely to survive at 900.
>
>James Long
>Owner/Designer
>Lil Brother LLC (Instrument Division)
>----- Original Message -----
>From: "Daniel Lance" <lanceind@earthlink.net>
>To: <personal_submersibles@psubs.org>
>Sent: Wednesday, July 25, 2007 8:04 PM
>Subject: RE: [PSUBS-MAILIST] Welding Revisited
>
>
>James,
>If you tell a welder his welds are going to be x-rayed when the job is
>completed there is a tendency for that person to be more diligent in his
>work.
>X-ray "quality"welding as it applies to Pressure Vessel Quality work means
>a bare minimum of porosity, slag inclusions, undercut etc. and no tolerance
>for lack of complete penetration and/ or non fusion in the root pass. A
>submarine pressure hull must be built to PVQ standards to acheive 100% of
>the hull integrity needed for its intended purpose.Setting the "bar" high
>for selecting a weld process, procedure or weldor is whats necessary for
>such a demanding application. Most psubers won't spend the money to x-ray
>their welds , but would'nt you like to know they would pass a test if you
>did one ? If your hull fails at 200 hundred feet you will be just as dead
>as if it failed at 900 feet.
>Dan Lance
>
>
> > [Original Message]
> > From: Lil Brother LLC <lil_brother_llc@bellsouth.net>
> > To: <personal_submersibles@psubs.org>
> > Date: 7/25/2007 12:45:47 AM
> > Subject: [PSUBS-MAILIST] Welding Revisited
> >
> > Ok,
> >
> > We have discussed welding and the methods involved.
> >
> > Shouldn't we also discuss the situations that pertain to each type and
>the
> > critical requirement for each?
> >
> > I know that a professional welder knows what he is talking about, but I
> > think x-ray on welds that will never pass regular scuba diving depths is
>a
> > little extreme on the side of safety.
> >
> > I'm not knocking safety at all, I tend to lean to the safe side of
> > everything. But there is a point to overkill when it comes to safety
> > measures.
> >
> > I agree, if you are going to depths of 600 -1000 feet, I would
>definitely
> > have the most certified welder available, and have the welds tested by
> > x-ray.
> >
> > But I don't see the need to go to that measure if the sub is only going
>to a
> > max depth of 200 ft. I do see the need of the welds being proper,
>airtight
> > and strong.
> >
> > But I'm a realist, so I can handle the opinions from whoever disagrees
>with
> > me.
> >
> > James Long
> > Owner/Designer
> > Lil Brother LLC (Instrument Division)
> >
> >
> >
> >
> >
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