[PSUBS-MAILIST] Valve part 2

Wed May 26 10:15:39 EDT 2021

Hi David.

There was nothing on it originally.  It was a piece of XXH pipe as
specified on the K350 plans that I had thread cut with a BSPT pipe
threading machine at an engineering shop.

Anyway, i have ordered a 2" BSPT button die and handle to fit.  I think
this is quite possibly the single most expensive thing i have ever bought
just to do one small job.  But there we go, its got to be done.

So, assuming it arrives for this weekend, I will attempt to re cut the
threads.  I suspect the handles may need re making on the holder in order
to clear the curvature of the hull, but we'll see.  Failing that, i will
weld on a straight coupler.

Thanks
James

On Tue, 25 May 2021 at 18:57, David Colombo via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> James, what was connected to the nipple previously? If you still have it,
> I would try two things. How many turns would it take to reapply it, first
> ans then take your street El and screw it into the part as well. I believe
> that will tell you if the nipple is out of round or if the original fitting
> was actually only held on by two turns, in which case I would follow the
> advice and retap the old threads.
>
> Best Regards,
> David Colombo
>
> 804 College Ave
> Santa Rosa, CA. 95404
> (707) 536-1424
> www.SeaQuestor.com
>
>
>
> On Mon, May 24, 2021 at 9:25 AM James Frankland via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Thanks everyone.
>>
>> The thread is 2" BSPT on both obviously and I had the external one on the
>> pipe nipple cut at an engineering place with a powered pipe threader.
>> Agreed, ptfe tape will hopefully allow it to turn a little more.
>>
>> I think with the advice given, im going to try and thread the male
>> threads on the pipe nipple a bit deeper.  Ive been having a quick look at
>> pipe threading machines.
>>
>> Im going to see if i can hire one to start with.  Unlikely here i
>> suspect.  Also i will go to the place i originally had it threaded and see
>> if i can borrow something.  I know them quite well there.
>>
>> Did find some manual ones,
>>
>>
>> https://www.amazon.co.uk/Sealey-PTK992-Threading-8-inch-2-inch/dp/B000R9W1A6/ref=sr_1_3?dchild=1&keywords=2%22+pipe+threader&qid=1621872818&s=diy&sr=1-3
>>
>> but they look a bit poor quality.  There are better, but look at the
>> price...But might just do it for this one job, especially as the threads
>> are cut mostly already.  Might need to get some better cutting dies?
>> Anyway, im not even quite sure how they work so will look at some videos
>> later.
>>
>> Anyway, i have some options.  Keep any ideas coming, it really helps.
>> Thanks again.
>> James
>>
>>
>>
>> On Mon, 24 May 2021 at 15:09, Sean T. Stevenson via Personal_Submersibles
>> <personal_submersibles at psubs.org> wrote:
>>
>>> First off, can you confirm that both the male and female thread are of
>>> the same thread standard (NPT, ISO / BSP, etc.)? These tapered thread forms
>>> are not all interchangeable.
>>>
>>> To get deeper engagement on a tapered pipe thread, you can run a tap in
>>> the female thread, or run a die over the male thread, or both. (Where the
>>> tools are available, it's never a bad idea to dress both sides of a tapered
>>> pipe thread connection prior to assembly just to avoid problems with fouled
>>> or damaged threads). In this case, I'd be inclined to try to dress the male
>>> thread with a die first, because it is likely out of true geometry due to
>>> the welding. A die that size won't be a cheap tool though if you don't
>>> already own it.
>>>
>>> Consider also the function of a PTFE (or similar) pipe thread sealant.
>>> The sealant actually serves three purposes, the first of which is, as
>>> expected, to seal the spiral thread gap. The second purpose is to prevent
>>> galling between similar alloys (particularly an issue with AISI Type 316 /
>>> 316L stainless and equivalents like CF-8M) during make up. The third, and
>>> arguably most important purpose is to act as a thread lubricant which
>>> facilitates greater engagement and interference of the tapered thread by
>>> reducing the rotating friction between the parts, ultimately resulting in a
>>> smaller gap to be sealed, and consequently a more successful seal.
>>>
>>> When working with tapered threads, I typically tighten them hand tight
>>> plus 1.5 to 3 full turns, but that is specifically with smaller diameter
>>> fittings. 2" and larger fittings may have different recommendations for
>>> number of turns as someone else already mentioned, and of course often
>>> tapered threads are used to make up fittings with a final required
>>> orientation, which isn't necessarily ideal for obtaining optimum assembly
>>> torque / engagement. Importantly though, "hand tight" applies to a
>>> connection which has first been lubricated with pipe thread sealant, and
>>> will typically be quite a bit further engaged than when test fit dry.
>>>
>>> Sean
>>>
>>> -------- Original Message --------
>>> On May 24, 2021, 02:05, James Frankland via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>
>>> Hi all.
>>> I didn’t get any responses to my valve dilemma.  I’ve made another video
>>> with the problem right at the start so you don’t have to watch it all.  I
>>> would really appreciate some advice here, I’m not sure what to do.
>>>
>>> https://youtu.be/qJhVeFrUwWI
>>>
>>> Thanks James
>>> _______________________________________________
>>> Personal_Submersibles mailing list
>>> Personal_Submersibles at psubs.org
>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>
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