tapered/NPT -vs- straight/BSP - is BSPP worth the cost?

[orangetree]

In another life (work $ + robustness requirements) we would go BSPP 100% given the choice. It's a better design, relying on the elastomeric seal is generally regarded as being much more robust than relying on sealant and thread deformation.

Custom hydraulic work, on my own, is new to me, though - and BSP is double the cost, with lower availability in the US. What are your thoughts on NPT vs BSPP?

The project I need to complete is a handful of as-compact-as-possible little bends, tees, etc to shove some check valves where they aren't commonly placed, integrated with a few new directional circuits. Requirements include 2500-3000psi, with no significant temperature exposure, minor physical damage concern (it's a tractor), and critically I'll undoubtedly need to be disassembled/reassembled a time or two.

Thanks!

 

[WranglerX]

IF its all about availability go with the one that gives you more choices and more product availability..... NPT has been around for a million years, its not that difficult to get proper thread seal with some of the sealing chemicals available today,,,,

Thread Sealants

Thread sealants prevent fluid leaks on metal pipes and joints

www.henkel-adhesives.com

 

[oldnslo]

In the USA SAE O-ring boss is very common port style and fittings are usually available at any decent hydraulic store.

 

[oldtimer 66]

Go to the Surplus Center in Lincoln Nebraska. Here is the link to there hydraulic section. Hydraulics | www.surpluscenter.com. Then go to there Hydraulic Adapters and Fittings section. They have about any thing you would want in hydraulic components plus tons of other products. They also show the on hand quantities. I have bought there in years passed will no problems.

 

[MtnViewRanch]

In another life (work $ + robustness requirements) we would go BSPP 100% given the choice. It's a better design, relying on the elastomeric seal is generally regarded as being much more robust than relying on sealant and thread deformation.

Custom hydraulic work, on my own, is new to me, though - and BSP is double the cost, with lower availability in the US. What are your thoughts on NPT vs BSPP?

The project I need to complete is a handful of as-compact-as-possible little bends, tees, etc to shove some check valves where they aren't commonly placed, integrated with a few new directional circuits. Requirements include 2500-3000psi, with no significant temperature exposure, minor physical damage concern (it's a tractor), and critically I'll undoubtedly need to be disassembled/reassembled a time or two.

Thanks!

Why would you use anything other than JIC or O-ring boss fittings for all your plumbing?
JD is big on face seal fittings.

 

[orangetree]

Why would you use anything other than JIC or O-ring boss fittings for all your plumbing?
JD is big on face seal fittings.

Well, thats sort of the impetus fpr the question. Putting in an surpluscenter order, they stock the BrandHyd checks i was looking for - but (literally) 2x the cost for the flatfaced vs taper, and even they have ~30 npt's in stock, but only 3 bspp's (i need 4

So yeah, parrallel, flat sealing are way better - but in my first attempts to source availability is bad - looking for opinions on if its just a fools errand to try to stay away from taper.

 

[etpm]

In my experience of over 40 years of machining, much of that making hydraulic parts that used various types of fittings, NPT threads are used for situations where the fitting is usually only to be assembled once, and when high pressure is involved NPT fittings were rarely used and when used they were made o be assembled only once, period. In fact, when tapered threads were used it was usually NPTF, AKA Dryseal. Really, tapered threads are best used in low pressure assembled once situations. It is definitely worth it to spend more money on systems that don't rely on the threads for the sealing but instead other seals, such as o-rings.
Eric

 

[ericm979]

JIC except where you connect to something with a different type of fitting. It's really common in the US and works well.

 

[kennyd]

Why would you use anything other than JIC or O-ring boss fittings for all your plumbing?

^^^^
THIS.

ORFS for a distant 3rd. NPT should be outlawed.

 

[oldnslo]

NPT has one advantage over other fittings in that they rarely fail and cause and oil mist which is very important fire zones like quench tank for heat treat furnace. They typically just drip. On O-ring boss or BSPP with elastomer seal when seal fails you get mist.

This is the only advantage I can think of other than cost for NPT.

 

[Harry in Ky]

Another vote for O ring ports. BSPP may be as effective, but much more expensive, with fewer options as far as fitting style and multi-sizing combinations available. O ring fittings can be found anywhere. For me, it's O ring port components and JIC lines and hoses. NPT is rarely an option except in cases where the component is only available that way.

 

[hayden]

I hate NPT. Very prone to leaking, and very difficult to fix when they do leak, especially if you have a bunch of stacked parts like you have planned. O-ring Boss (ORB), or o-ring face seal (ORFS), or JIC are my preferences. Also check DiscountHydraulicHose.com

 

[Tinhack]

Really, tapered threads are best used in low pressure assembled once situations.

Hogwash! All my shop 10,000 psi pumps and hoses use NPT fittings. If your NPT fitting is leaking, it was installed incorrectly. Any fitting will leak if you don't know how to use it.

 

[etpm]

Hogwash! All my shop 10,000 psi pumps and hoses use NPT fittings. If your NPT fitting is leaking, it was installed incorrectly. Any fitting will leak if you don't know how to use it.

Good for you. I'm glad your stuff doesn't leak. And I'm sure you regularly unmake and remake those NPT connections. Nevertheless it doesn't change the facts stated in my post. Because they are facts.
Eric

 

[Shenandoah MF1760]

One of the issues with NPT is the same with anything, cheap garbage from overseas.

I've seen people split low quality NPT fittings with loose threads in an attempt to get them to seal, despite pipe dope or tape even on systems below 150 psi.

I like BSPP, but it's usually only available at industrial suppliers and typically in stainless.

It all boils down to what's the application, how permanent is the installation, how much are you willing to spend, how long are you willing to wait on parts, and are the o-rings (if involved) compatible with the fluid?

If I was running pipe for natural gas, propane or a compressor I'd probably go cheap with black iron and NPT.

If I'm working on my tractor I'd go stainless and braided hoses with BSPP, the brewery I'd use stainless and tri-clover fittings.

 

[aa2tn]

Well I worked in an aerospace company's hydraulic maintenance department for 20 years and we used everything. Pressures up to 10K, temperatures up to 250F, and several different fluids. Most all, probably 90 percent of our leaks were fittings with O-rings. If money or availability is a problem mix in just enough O ring fittings to make it easy to repair when the time comes. One thing we always did with not fittings is to use both tape and dope, and stay off the first thread to avoid contamination issues.