The Steamboating Forum

What would be the "Right/safe" way to convert 1/2"BSP to 1/2"NPT for a water gauge connection to boiler?

Only with the appropriate adaptor. BSP and NPT may have the same tpi at 1/2" dia, but the angles of the thread form are different (55 and 60 degs. respectively). Close, but not close enough for pressure.

Mcmaster has some adaptors that may be suitable...

http://www.mcmaster.com/#=p17f2k


- Bart

In my opinion the right/safe way to go about this would be to weld up the hole and re-tap or use the correct fitting for the job. Using an adapter would space the gauge further from the boiler making it easier to break off if someone were to fall against it. I would only use an adapter if it were the last resort to getting home afloat or walking.

Messing about with extremely hot water under pressure is not something you recover from with an OOPS!

Scott

How about ANSI flanges ?

Cyruscosmo wrote:In my opinion the right/safe way to go about this would be to weld up the hole and re-tap or use the correct fitting for the job. Using an adapter would space the gauge further from the boiler making it easier to break off if someone were to fall against it. I would only use an adapter if it were the last resort to getting home afloat or walking.

Messing about with extremely hot water under pressure and is not something you recover from with an OOPS!

Scott

I cannot disagree with what you say but an adaptor does not need to be very long, and under our code (UK) any welding or alteration of the boiler would require another hydro test, as it would qualify as a repair.

How about ANSI flanges ?

If you already have the bolt holes for those flanges that would be a better way to go.

On another note if welding up the hole and re-taping is out of the question for boiler certification reasons then make sure you get the heaviest adapter you can. I don't know what your boiler ports are configured like but I will assume the ports in question are female. A female, male adapter would not stick out that much. I am a bit biased because working where I do I have found that if it can be broken off then some duffus will figure out a way to do it accidentally. If you have a way you could install an extra guard around the whole setup that would help.

Maybe I am a bit paranoid because the steam gear I work with runs at 2200 pounds. When a fitting goes things get really interesting! And when a safety fails the boom usually draws a big crowd of uniforms wanting to know what the hell that was?

Cheers
Scott

I wouldn't get too concerned with using an adapter to connect a gage. If it worries you - don't support the gage from its connection. Instead, hard mount the gage and connect it to the boiler with a 1/4" copper line (with the requisite loop, of course). After all, you're not trying to flow a lot of steam through this connection!!

On Otter I used a heavy tee and plugged one port w/ a solid connection to some existing framework; I sense boiler pressure w/ a small copper line. This has never given any trouble in the 17 years I've used it.

- Bart

I wouldn't get too concerned with using an adapter to connect a gage. If it worries you - don't support the gage from its connection. Instead, hard mount the gage and connect it to the boiler with a 1/4" copper line (with the requisite loop, of course). After all, you're not trying to flow a lot of steam through this connection!!

Barts I thought Johnp was talking about a water level gauge? If that is the case then an adapter would not be a problem as long as the gauge is mounted on something solid.

My Bad!

Cheers
Scott

I have no idea, actually... you may have been right.

A 1/2" BSP to 1/2" NPT adaptor is basically a fairly close nipple, in any case, so as long as it's turned from stock it will be fine in either application.

The maximum loads on the plumbing in our boats come from trailering, I think; jarring down some of these pot-holed wonders. Large heavy reflex gages should be supported and not cantilevered out too far.

- Bart