[PSUBS-MAILIST] Valve part 2

Tue May 25 13:55:52 EDT 2021

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
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