[PSUBS-MAILIST] Clearances

Tue Dec 10 14:03:25 EST 2024

Definitely try to get a quote for in-situ machining of the seat. If you trailer the boat to the machine shop, it could end up being cheaper than re-machining the window and then sending it out for a full anneal.

On Tuesday, December 10th, 2024 at 11:34, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

> Rick, I would do some more research on annealing your port again. If I recall, a window is only allowed one annealing cycle. The reason for annealing after machining is due to heat build up for machining. I have machined and tested ports without an annealing cycle. The trick is to take super small passes .005 and even spray water on it as its cutting. I was talking to a machinist one time about machining domes and he put ice water in the dish to keep it cool.
> Its been a while since I worked on this, so check it out, in case my memory is off.
> Hank
>
> On Tuesday, December 10, 2024 at 10:55:04 AM MST, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> Hey Sean,
> The viewports are flat. Thanks for the data.
>
> On Tue, Dec 10, 2024 at 6:12 AM Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>> Rick, is this a flat disc viewport, and not a dome?
>>
>> See an excerpt from ASME PVHO-1-2023 below. Do, where referenced, is the window major diameter.
>> 2-2.11.4 Flat Disk Windows
>>
>> 2-2.11.4.1 Window External Diameter.
>>
>> The dimensional tolerance of 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 (+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 +0.00/−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.
>>
>> 2-2.11.4.2 Seat Cavity Diameter.
>>
>> 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/−0.00mm) 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/−0.00mm) 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/−0.00mm) 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.
>>
>> Sean
>>
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>
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