[PSUBS-MAILIST] Gamma ring machining

[Stephen Fordyce via Personal_Submersibles]

Hi Hank,
We used a flame facing machine recently at work to do a stainless steel
flange on a pressure vessel about 800mm ID. We hired it to use ourselves at
great expense, and the thing weighed a couple of hundred kilos, was very
solid.

The fitter who did the job was very experienced machinist (but hadn't used
one before) but could not get the finish very smooth - I can't find photos
sorry, but it was like regular machining grooves but much larger - and it
looked pretty ordinary. He spent several hours with a grinder cleaning it
up.

On balance, it probably would have been easier to just flatten it manually
with a grinder (but it was on a live liquefied natural gas plant and they
don't like sparks:) ). Wasn't critical to get a flat face as we were just
making room for a gasket in a slot to have more compression.

After getting it pretty flat with a straight edge, the fine stuff/quality
control could be done by a thin layer of paint on a known flat plate or
machined flange which you put on the welded flange and then where there is
no paint deposited, you know that area is too low. Obviously paint is no
good, but colored oil or 2-layered carbon paper (nice because then you have
a trace of it) would probably work, or charcoal.

Cheers,
Steve
On 06/03/2015 11:40 PM, "hank pronk via Personal_Submersibles" <
personal_submersibles at psubs.org> wrote:

> Brian,
> No, the machine is connected to the inside lip of the ring.  The machine
> rotates on a center pivot.  The cutter rotates instead of the part.
> Hank
> --------------------------------------------
> On Thu, 3/5/15, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>  Subject: Re: [PSUBS-MAILIST] Gamma ring machining
>  To: "Personal Submersibles General Discussion" <
> personal_submersibles at psubs.org>
>  Received: Thursday, March 5, 2015, 9:15 PM
>
>  Hank,  are you going to be
>  turning the whole fricking sub ?
>
>  Brian
>
>  --- personal_submersibles at psubs.org
>  wrote:
>
>  From: hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org>
>  To: personal_submersibles at psubs.org
>  Subject: [PSUBS-MAILIST] Gamma ring machining
>  Date: Thu, 5 Mar 2015 18:00:24 -0800
>
>  Today my welder came to my shop and welded the reinforcing
>  ring into Gamma, 10 passes, looks perfect!
>
>  Next step, machine the ring.  I am going to make a
>  flange facing machine from a one ton  truck full
>  floater differential hub and a part or two borrowed from my
>  spare lathe.  The rig will be hydraulic drive.
>  This may or may not work.  :-)  If it works and I
>  am confident it will, I can also face CT lands, with the CT
>  welded in place.
>  Hank
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