What's new
What's new

BSPP O Ring Seat/Mating Surface

Feb 23, 2024
Hi all - first time poster here. Hopefully this is a straightforward one!

I'm using a BSPP to hose barb adapter from McMaster. I need to design a manifold block that this adapter would thread into. I haven't been able to find specific details on the geometry and features of what this mating surface should look like. I don't mean to overthink it, but I'd like to define the manifold block such that I have the appropriate sealing features that would correspond to the o ring.

Should I simply treat the mating surface as a face sealing o ring? That is, according to Parker, flat and with a 32 finish? Thank you!
Why would anyone in the US design something to use BSPP? There are other choices that can be locally sourced and have several magnitudes greater usage. ORB (o-ring boss) would be similar.
You can get BSPP porting tools just like the SAE porting tools. I have several of them from projects that were ending up around the world where these are much more common. If not a dedicated tool, they are very similar to the SAE configuration.
Ok. The part is readily available and affordable on McMaster. It uses an O ring seal which I am comfortable with. How would one, in theory, specify the mating surface for said BSPP component?

Could you recomend a comparable ORB-to-barb adapter? Similarly, how would one specify the geometry and features of the mating surface?
If this is for your own use I'd design the manifold around the fitting rather than vice versa. Get a NPT hose barb and you won't have to make a special port configuration.
How many are you making? How complicated are these? Are you going to make them yourself or are you trying to draw and specify to send out?

The reason why I ask is that there are a few manifold machine shops out there that all they do is pump out manifolds. My experience is that they are lower cost for manifolds than most machine shops as that's all they do. In such a case all you do is call out the port and they put it in. I haven't used much BSPP only when I can't get it in SAE if maybe I am designing a machine for a European customer who wants me to use European parts.
I designed a number of manifolds over the years. It's a low pressure static application so not critical, always used Parker's recommendations. Seaman has steered you in the right direction. Let me add that the crucial thing is to make sure the mating surface between fitting and manifold close up with no gap. The thread axis needs to be at a true right angle with the mating surface. That insures next to zero gap that the O Ring could extrude into. You want the fitting and the manifold to mate without a gap.
Last edited: