Anyone know about BSPP pipe fittings?

[Dan Friedrichs]

I have a power washer unloader (General Pump ZK1) that has an "3/8 BSPP-M" outlet. I understand that BSPP is a parallel thread that requires a washer to seal, but this fitting doesn't have a flat face for a washer to press against; rather, it has a concave flare that would seem to be the sealing surface.

So what's this called? Is there such a thing as a BSPP-M fitting that seals with a flare instead of a washer? I just can't seem to find the right term to describe this. I'm ultimately trying to connect a 3/8 NPT-M hose to it...

[Mark Bolton]

You need to look for British standard parallel pipe swivel. BSPP stands for British standard parallel pipe but that's a straight thread fitting with the cone seat in the center. It's not alive swivel. But the style of fitting you need is called a swivel

[Dan Friedrichs]

Thanks, Mark.

I bought a fitting like this, but it's just a straight BSPP female coupler, so while it screws on just fine, it doesn't have any sealing surface (no cone or o-ring):
https://www.mcmaster.com/4936K949/

Are you saying I need something like this? It's hard to tell from the drawing if this has the mating cone:
https://www.mcmaster.com/4936K376/

[Mark Bolton]

I didnt find a female in a quick search but I believe you need to be looking for something like this:

https://www.new-line.com/fittings/orb-orfs-metric-hydraulic-adapters/jis-bsp-din-and-metric-hydraulic-adapters/mnpt-x-fbspp-swivel

and the part number N9023-06-06 in that list would be a -06 (3/8") male npt to -06 (3/8") female bspp swivel.

N9023-06-06

I dont see any of those in McMaster. Your best bet would be a full service local hydraulic shop like a Parker Store if there is one in your area. That fitting above doesnt get you to female, you'd have to use a 3/8" NPT coupling to get to female but nothing pops up in female on a quick search.

[Mark Bolton]

These are europe but you can click on the diagram and see the cone seat.

https://www.customfittings.com/bspp-cone-seat-swivel-female-x-npt-male-adaptor

[Malcolm McLeod]

Thanks, Mark.

I bought a fitting like this, but it's just a straight BSPP female coupler, so while it screws on just fine, it doesn't have any sealing surface (no cone or o-ring):
https://www.mcmaster.com/4936K949/

Are you saying I need something like this? It's hard to tell from the drawing if this has the mating cone:
https://www.mcmaster.com/4936K376/

Dan, is it possible that the fitting seals the face of the fitting (outer end of the threads), rather than sealing against the shoulder...?? Much like a hose bib and hose connection. A (rubber) flat washer 'inside' the receptacle then might be the resilient seal.

(Just scatter-shooting based on the design - - I'm not sure I've ever had a BSPP fitting in my hands other than as an accident perhaps.)

*************
I got curious, and I should have looked first....

This is a description of the 'seal mechanism':
BSPP pressure gauges have a longer male thread and use a copper crush washer that is squeezed in between the bottom of the male fitting and the bottom of the female BSPP hole forming a pressure tight seal. No thread sealant is needed to form a seal.
So it sounds like it does seal against the thread face.

Maybe search for "BSPP bonded seal" - it looks to be a steel washer bonded to inner flex 'gasket' intended for sealing in this manner, but not copper based.

Or there does appear to be a shoulder sealing option: This might be a source (https://shop.hoseandfittings.com/catalog/Fitting/Steel/Metric_Compression/1005%3Cbr%3ECOMP%3Cbr%3EMBSPP%3Cbr%3Ew__Seal/1005-10S-08.html?gclid=CjwKCAiAnvj9BRA4EiwAuUMDf6UhCpUezln9 Vqabh4-yjIkMqgPNl2CfnVPBtU2dt8bSp3DinbNsbhoCuoQQAvD_BwE) or maybe this (https://shop.prmfiltration.com/products/brass-adapter-1-2-inch-npt-female-x-1-2-inch-bspp-male-with-sealing-washer?variant=13043533185087&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&keyword=&utm_medium=ppc&utm_term=&utm_campaign=GS+-+Fittings&utm_source=adwords&hsa_kw=&hsa_cam=9568893094&hsa_ver=3&hsa_acc=5711099154&hsa_ad=423270125967&hsa_grp=101125649031&hsa_src=g&hsa_mt=&hsa_tgt=pla-297767874615&hsa_net=adwords&gclid=CjwKCAiAnvj9BRA4EiwAuUMDfxBcsR-zOKP6iF-xqsMBK5ynkFOzNPxzFPpJo4gvAlx-uHOKJRmiBhoCXjsQAvD_BwE) - - or at least narrow your search terms?

[Mark Hennebury]

Try John Guest website;https://www.johnguest.com/our-products/

[Brad Chenoweth]

Dan,

I think Mark is on the right track. The shop I work for makes some British Pipe fittings, but not like these. Incidentally. British Pipe threads are basically identical to ours, except the thread form is 55° instead of 60°. Male BSPP threads are "not suitable for pressure tight joints", so they need some other form of mechanical seal, like a gasket or flare seat.

[Malcolm McLeod]

https://www.adaptall.com/info-tutorials/sealing-methods.php

Handy little tutorial on identifying tube fitting seal types.

[Mark Bolton]

https://www.adaptall.com/info-tutorials/sealing-methods.php

Handy little tutorial on identifying tube fitting seal types.

Right, nice link pertaining to the fitting show in his original post. BSPP cone seat.

[Bruce King]

Northern tool probably has it.

[Dan Friedrichs]

I didnt find a female in a quick search but I believe you need to be looking for something like this:

https://www.new-line.com/fittings/orb-orfs-metric-hydraulic-adapters/jis-bsp-din-and-metric-hydraulic-adapters/mnpt-x-fbspp-swivel

and the part number N9023-06-06 in that list would be a -06 (3/8") male npt to -06 (3/8") female bspp swivel.

N9023-06-06

I dont see any of those in McMaster. Your best bet would be a full service local hydraulic shop like a Parker Store if there is one in your area. That fitting above doesnt get you to female, you'd have to use a 3/8" NPT coupling to get to female but nothing pops up in female on a quick search.

Thanks, Mark - that's what I need! Looks like the term is "BSPP swivel". I found the same on a different site for $8 with free shipping, so I guess you can't beat that. Surprised McMaster doesn't seem to have it. Thank you!