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Old 05 January 2021, 05:06   #1
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1/2" npt

https://www.tidalwake.com/product/un...in-plug-light/

Does anyone know where I can get a skin fitting from to take this light = the one on my Avon 310 seems is BSP and just slightly different size - trawled internet and cant find anything...

Thanks
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Old 05 January 2021, 06:42   #2
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Do an online search for 'garboard drain plug 1/2" NPT'.
e.g https://www.ebay.co.uk/sch/i.html?_f...vice=c&mkcid=2
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Old 05 January 2021, 06:52   #3
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Thank you - came up inner thread 0.63" - not sure if thats correct or not - so i have ordered - hopefully fits - no idea why 1/2" NPT female so damn impossibel to find??
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Old 13 January 2021, 22:41   #4
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Originally Posted by nw04jen View Post
Thank you - came up inner thread 0.63" - not sure if thats correct or not - so i have ordered - hopefully fits - no idea why 1/2" NPT female so damn impossibel to find??
Looks like 3/8 NPT which is 0.67

1/2 NPT is about 0.84
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Old 14 January 2021, 00:49   #5
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Threads are a pain!

Many times I have tapped a thread out to the size I want rather than search endlessly for the correct fitting.

For example both 1/2 inch NTP and BSP have the same pitch. (Number of threads per inch).

However BSP is slightly larger in OD. Running a tap down the thread will fix it if you are fitting BSP into NPT.

Fitting NPT into BSP you have to take into consideration that the NPT is tapered, where the T in NTP comes from and although the thread seems loose at the front end cutting the end off and using the larger dia at the rear of the thread will probably fit OK aided with some thread tape.
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Old 14 January 2021, 02:23   #6
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Originally Posted by Salty Pete View Post
Threads are a pain!
I agree with you SP but otherwise you posted misinformation.

American National Pipe Thread (NPT)
British Standard Pipe Thread (BSP or BSPT)

1. Either (male) thread can be tapered. This is the norm for pipes.
2. NPT has a 60deg thread angle, BSP 55deg. Sounds a small difference but is in fact a big deal if you wanted mismatched fittings to hold pressure. (taper takes care of any OD diff)
3. The threads per inch (TPI) is not always the same
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Old 14 January 2021, 03:53   #7
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Originally Posted by Limecc View Post
I agree with you SP but otherwise you posted misinformation.

American National Pipe Thread (NPT)
British Standard Pipe Thread (BSP or BSPT)

1. Either (male) thread can be tapered. This is the norm for pipes.
2. NPT has a 60deg thread angle, BSP 55deg. Sounds a small difference but is in fact a big deal if you wanted mismatched fittings to hold pressure. (taper takes care of any OD diff)
3. The threads per inch (TPI) is not always the same
Love this!! Straight the zeus book!
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Old 14 January 2021, 04:16   #8
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Love this!! Straight from the zeus book!
Aah yes. Still have my 1981 copy! 25 years in engineering and fabrication as fitter and machinist before completely changing career 14 years ago. Threaded more than my share of blue band.
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Old 14 January 2021, 19:27   #9
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Quote:
Originally Posted by Limecc View Post
I agree with you SP but otherwise you posted misinformation.

American National Pipe Thread (NPT)
British Standard Pipe Thread (BSP or BSPT)

1. Either (male) thread can be tapered. This is the norm for pipes.
2. NPT has a 60deg thread angle, BSP 55deg. Sounds a small difference but is in fact a big deal if you wanted mismatched fittings to hold pressure. (taper takes care of any OD diff)
3. The threads per inch (TPI) is not always the same
Yes, and that's why I run a tap down them.

Like BSP and UNC same pitch and dia different thread form.

Tap it.

Changing the thread form doesn't alter the strength, in fact I did it on an airline about a month ago to set up my compressor to pump up my RIB.
The gauge I ordered had what my fittings supplier called "Chinese Metric" and nothing seemed to fit. Yep a Tap and Die set fixed it.

Incidentally I do try to obtain the correct fittings if possible.

That's the only time I wished I wasn't retired, because I was a machinist and could machine up any fitting I wanted.
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