Re: [PSUBS-MAILIST] warning for smyth

[protek@shreve.net]

    Grinding welds down does not make one "idiotic."  It is a standard practice
in industry to dress welds by either machining or grinding.  There are even
certain conditions that can worsen a weld if it is not ground.
    I spent a few minutes on the web this morning at work and found several
reverences to the grind or don't grind issue.  I have listed these below.

http://www.cycling.org/lists/mtb/mtb-archive-hyper/mtb.199503/1330.html

http://www.dot.state.ga.us/dot/construction/materials-research/Documents/ppt/vis_inspect/tsld016.htm


http://www.lambolounge.com/Building_Notes/Welding/Welding.htm

Gary Boucher

>Gary,
>
>I sure you saw my response to Alec, but if not, I was just making sure that

>he wasn't trying to buff/grind a weld bead down to make it pretty or more
>hydrodynamic since I see such idiocy all the time in the aircraft industry.

>Thanks for the reassurance and restoring my confidence in PSUB builders
>everywhere. BTW I speak from experience. I ground a weld bead down on a
>liquid-fuel rocket engine I made a few years ago and when I pressurized the

>cooling jacket and fired it up, the bead cracked and shot out a jet of
>steam, ruining the cooling capabilities of the engine. I never fixed it, but

>it was a good experience as I later learned, while in a welding class, that

>you should never grind on weld beads. consequently, I have applied this to

>my submarining endeavors. Hope all is well with everyone. I should have a
>major update on the UASUBS Initiative soon for any interested party...
>
>- Jacob Lauser
>
>----- Original Message -----
>From: "Gary R. Boucher" <protek@shreve.net>
>To: <personal_submersibles@psubs.org>
>Sent: Wednesday, September 25, 2002 7:43 AM
>Subject: Re: [PSUBS-MAILIST] warning for smyth
>
>
>> Mr. Lauser,
>>
>>      They radiograph and use ultrasonic methods to find cracks and flaws

>in
>> a weld.  Exactly how would you suggest fixing a flaw?  Perhaps drill it
>> out?  Of course you grind it out.  There is no way other than to throw the

>> hull away and start over.  That is the method used by certified welders
>and
>> has been since the beginning.
>>      As far as grinding of a finished weld goes, it does tend to weaken
>the
>> weld, but all must be considered in the larger scope of things such as the

>> amount of stress the weld will be subjected to and the types of materials

>> used.  If you want to see some grinding, I suggest you come look at my
>> sub's sail section.
>>      I have met Smyth, and sir, I can assure you he is paying attention.

>>
>> Gary R. Boucher, D.Eng.
>> Dept. Chemistry-Physics
>> Louisiana State University - Shreveport
>>
>>
>> At 06:28 PM 9/24/2002, you wrote:
>> >ATTENTION ALEC SMYTH:
>> >
>> >Alec,
>> >
>> >It was great to see your progress on the SOLO sub, but I read something

>> >that caused me great concern for your safety, so if you're listening,
>> >please pay attention! I'm sorry to post this over the list, but I didn't

>> >have your e-mail address at hand.
>> >
>> >In your description from August 29th, you mentioned a few things needing

>> >attention and in one you said "grinding out small welding flaws in the
>> >hull". I don't want to be an alarmist, and perhaps someone else has
>> >brought it to your attention (hopefully), but you should NEVER EVER EVER

>> >EVER grind on a weld. It will weaken the weld and can seriously endanger

>> >your submarining efforts if it is on the pressure hull. I say this only

>to
>> >keep you safe. I can only imagine, not that I particularly want to, what

>> >could happen to a weakened pressure hull weld at depth. Please be careful

>> >since it looks like such a cool sub and I wouldn't want anything to
>happen
>> >to the operator. Good luck and keep working hard!
>> >
>> >- Jacob Lauser
>> >   University of Arizona Student Underwater Bouyancy System Initiative
>> > (UASUBSI)
>> >
>>
>>
>>
>>
>
>