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Re: [PSUBS-MAILIST] Viewport Question.
James, this is all covered in sections 2-2.12.8 and 2-2.12.9 of ASME
PVHO-1-2002:
2-2.12.8
The dimensional tolerance on the external diameter of the window shall be
based on the type of sealing arrangement for the window.
a) The external diameter of the flat disk window shall be within +0.000/-0.010
in. (+0.000/-0.25 mm) of the nominal value if the window is to be sealed in
the seat cavity with a radially compressed O-ring.
b) The external diameter of the flat disk window shall be within +0.000/-0.060
in. (+0.000/-1.5 mm) of the nominal value if the window is to be sealed in
the seat cavity with a seal ring wedged into the annular space between the
retaining ring, the window's bevel, and the cylindrical surface of the seat
cavity.
c) The external diameter of the flat disk window shall be within+0.0/-0.125 in
(+0.0/-3.2 mm) of the nominal value if the window is to be sealed in the seat
cavity with a flat elastomeric gasket axially compressed by the retaining
ring.
d) The external diameter of the flat disk window shall be within +0.0/-0.02 Do
of the nominal value if the window is to be sealed in the seat cavity with a
room-temperature, curing, elastomeric compound injected into the annular
space between the edge of the window and the cylindrical surface of the seat.
e) The plane bearing surface of the flat disk window shall not deviate more
than 0.001 Do from an ideal plane.
2-2.12.9
The dimensional tolerance on the external diameter of the window seat cavity
shall be based on the type of sealing arrangement for the window.
a) The diameter of the seat cavity for a flat disk window shall be within
+0.01/-0.00 in. (+0.25/-0.00 mm) of the nominal value if the window is to be
sealed in the seat cavity with a radially compressed O-ring.
b) The diameter of the seat cavity for a flat disk window shall be within
+0.06/-0.00 in. (+1.5/-0.00 mm) of the nominal value if the window is to be
sealed in the seat cavity with a seal ring wedged into the annular space
between the retaining ring, the window's bevel, and the cylindrical surface
of the seat cavity.
c) The diameter of the seat cavity for a flat disk window shall be within
+0.125/-0.000 in (+3.2/-0.00 mm) of the nominal value if the window is to be
sealed in the seat cavity with a flat elastomeric gasket axially compressed
by the retaining ring.
d) The diameter of the seat cavity for a flat disk window shall be within
+0.01 Do/-0.000 of the nominal value if the window is to be sealed in the
seat cavity with a room-temperature, curing, elastomeric compound injected
into the annular space between the edge of the window and the cylindrical
surface of the seat.
e) The plane bearing surface of the seat cavity shall not deviate more than
0.002 Do from an ideal plane when measured with a feeler gauge inserted
between the mating plane surfaces of the flat disk window or a circular plug
gauge and the bare seat cavity. The axial force used to seat the window or
the plug gauge shall not exceed 10 Do lb. (4.53 Do kg) applied uniformly
around its circumference.
Do, where referred to above, corresponds to the outer diameter of the window.
-Sean
On December 11, 2007 03:02:20 James Frankland wrote:
> Hello All.
>
> Quick question regarding viewports tolerance.
>
> Ive started machining and have done 2 at the moment. Ive machined the
> depth of the bore to be exactly 1.25 inches as per the plans, and the
> inside diameter i have machined to 8 inches plus a clearance of 0.5 mm to
> allow the lense to drop in. (sorry, the plans are imperial but we're
> metric here, so its a bit of both).
>
> Im not making the acrylic lenses myself, i will buy them (probably from
> psubs store). Assuming they come in exactly at 8 inches OD, as things are
> they should slot in nice and tight.
>
> But Dan H mentioned to me that he got some slight distortion on the ports
> after welding.
>
> So the question is, do you think 0.5 mm clearance is enough? Obviously i
> cannot alter the ports once they are welded in, and don't want to have to
> start machining the lenses, they must fit.
>
> You can have a look here as usual. Some of the text titles are wrong.
> I'll change them later.
>
> http://www.guernseysubmarine.com/index_files/Page7497.htm
>
> Any thoughts?
>
> Thanks
> James
>
>
>
>
> ----- Original Message -----
> From: Jay K. Jeffries [mailto:bottomgun@mindspring.com]
> To: personal_submersibles@psubs.org
> Sent: Mon, 10 Dec 2007 20:16:42 -0500
> Subject: [PSUBS-MAILIST] Digital Multi-Frequency Scanning Sonar
>
> Here is what looks like a great scanning sonar for a PSUB. If it is priced
> like some of their other products, it should be a great deal.
>
>
>
> http://www.imagenex.com/html/881l_imaging.html
>
>
>
> R/Jay
>
>
>
>
>
> Respectfully,
>
> Jay K. Jeffries
>
> Andros Is., Bahamas
>
>
>
> A skimmer afloat is but a submarine, so poorly built it will not plunge.
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