[PSUBS-MAILIST] Pressure Test Chamber

Fri Jun 23 12:35:10 EDT 2017

Hi Hugh.  Thanks for the thread info.  Im pretty sure I have got only
Swagelok on my HP system.  But im going to sniff out the DK lok things
tomorrow.  I think I know where they are.  On the motor oil compensator
tubes.  If so it wont matter.

Regards
James

On 22 June 2017 at 23:34, Hugh Fulton via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi James,
>
> I am not saying the tube side is bad on the DK-Lok but when you have to
> check the threads then the Q.C. is missing somewhere and that is not a good
> sign.  Now that companies are getting things made in China you need to be
> watchful.  We have had issues with bolts, and seals from supposedly
> reputable companies now making in China or elsewhere.  One of the issues is
> the number of threads engaged due to thread tolerance on tapered threads
> such as BSP and NPT.  We have had fittings that only engage 3 threads.
> When we manufacture we always do 1 thread more than minimum tolerance as
> with high pressure you need thread engagement for safety.
>
>
>
> The above tale is from ASME VII Div 1 UG43.
>
>
>
> Hope that helps.
>
> Hugh
>
>
>
> *From:* Personal_Submersibles [mailto:personal_submersibles-
> bounces at psubs.org] *On Behalf Of *James Frankland via
> Personal_Submersibles
> *Sent:* Friday, 23 June 2017 3:14 AM
>
> *To:* Personal Submersibles General Discussion
> *Subject:* Re: [PSUBS-MAILIST] Pressure Test Chamber
>
>
>
> I think ive got some of those DK-lok fittings somewhere.  I don't think on
> the HP system as I used parker and Swagelok for those, but im going to
> track them down now.
>
>
>
> On 22 June 2017 at 00:15, Hugh Fulton via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alan,
>
> We have a pressure tester that goes up to 40,000 psi.  If you need to do a
> high pressure test we can assist.
>
>
>
> We had an explosion with a 1” line that was pressurised with 3,500 psi air
> but there was oil left in the line after hydrotesting with oil.
>
> The explosion blew out the side of the shed  and reached an estimated
> 25,000 psi in the pipes which ended up looking like Spaghetti.
>
>
>
> I had explained in detail to the guy who did the fitting of the pipes that
> everything had to be taken apart after the hydrotest and cleaned using
> solvent, then soapy water etc. as well as telling him stories of explosions.
>
> The guy, an aircraft engineer, did not do it properly and left oil in a
> branch tube, and I did not do a check on it.  Very lucky my son did not get
> killed as he opened the valve  doing tests.  These things do not just go
> pop when they fail and this forum needs to hear of these dangers.  The
> explosion was heard all round Clevedon. That was our first accident of that
> nature in 40 years of high pressure involvement. We only use water now for
> testing and make sure there is no air present.  We did have another
> incident when we hired out our tester to another company who tested a tank
> to 1500 psi and the sight glass was held in with a very fine thread.  The
> sight glass went through the roof iron along with the fittings and we never
> found the parts.  The inspector had looked in the sight glass about 20
> seconds before it let go.  If you are using tube fittings always
> disassemble after swaging and check the ferrules are in the right way and
> that a proper joint has been achieved.  There are some fittings which are
> copies and not up to the job.  We had issues with “DK-lok” (from Korea)
> with NPT threads where the taper was ½ the required taper but the thread
> gauge said it was OK. They were also not full form threads.   Also had some
> fittings called “Tubefit”  from I don’t know where and they were poor
> copies of “Swagelok”.
>
> We use SSP fittings out of USA which are fully interchangeable with
> Swagelok but in my opinion they are better quality.
>
>
>
> Air from a scuba tank over water is OK but make sure you have a concrete
> wall between you and the thing to be tested.  Also you should have an
> excess flow valve in the line.  You can get those from  Swagelok etc.
>
> Hugh
>
>
>
>
>
>
>
> *From:* Personal_Submersibles [mailto:personal_submersibles-
> bounces at psubs.org] *On Behalf Of *Alan via Personal_Submersibles
> *Sent:* Wednesday, 21 June 2017 5:58 PM
> *To:* Personal Submersibles General Discussion
> *Subject:* Re: [PSUBS-MAILIST] Pressure Test Chamber
>
>
>
> Thanks Greg & Hugh,
>
> there was a bit of doubt in my mind about it so mentioned my
>
> intended process. I have just googled accumulators in hydraulic systems
>
> & the danger of high pressure air! Yikes just as well I've got you guys
>
> looking out for me.
>
> What about air from the scuba tank pressurising water?
>
> I can get all the air out of the test chamber apart from the air in
>
> the line pressurising it!
>
> Other than that I have done some previous tests with the water blaster
>
> & may have to suffice with it's pressure!
>
> Cheers Alan
>
>
>
> Sent from my iPad
>
>
> On 21/06/2017, at 3:33 PM, james cottrell via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alan,
>
>
>
> Pressure testing that high needs to be done with liquid not gas. High
> pressure air is VERY dangerous. A pressure washer pump using water would be
> a safer choice.
>
>
>
> Greg
>
>
> ------------------------------
>
> *From:* Alan via Personal_Submersibles <personal_submersibles at psubs.org>
> *To:* personal_submersibles at psubs.org
> *Sent:* Tuesday, June 20, 2017 9:01 PM
> *Subject:* [PSUBS-MAILIST] Pressure Test Chamber
>
>
>
> I am making a plastic container to fill with water & stand inside my
>
> pressure chamber. There is a gap between the wall of the container
>
> & the chamber which I intend to fill with oil. There will be about an
>
> inch of air at the top of the chamber & I'm using a scuba tank to
>
> pressurise the unit up to 3000psi.
>
> Will car engine oil do to fill the gap between my plastic container &
>
> the chamber wall, or do I need to go with a hydraulic fluid.
>
> Am using the plastic container to keep water from rusting my test
>
> chamber. (Aussie Steve's idea)
>
> Cheers Alan
>
>
>
> Sent from my iPad
>
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