How to clock "G" (BSPP) threads?

[kb0thn]

I am doing pneumatic maintenance and repair on a 2000 vintage German made CNC router. Pneumatic fittings are all BSPP which I understand to be a straight thread that requires an o-ring on the face to seal. I guess these are now called "G" thread, which Parker says stands for "global". Fittings are mostly 1/4" with some 3/8" and 1/8".

Question: How the heck are you supposed to put fittings together into a given orientation and have them compress the o-ring enough to seal? On some it magically lines up. On others I am 1/2 a rotation away from where I need to be by the time the bodies bottom out on the metal washer surrounding the o-ring. With putting the fragile looking part in a bench vise and using a 8" long wrench I can get another 3/8 of a turn tighter before things are *really* bottomed out and I am about to break something.

It appears that somebody before me dealt with this by using various thread sealants and goops on the threads like I would expect to see on tapered threads. They skipped the o-rings all together. Is this the right way?

Thanks,

-Jim

 

[gustafson]

My thought is that the fitting is not correct for the situation you are in.

Is it a right angle fitting? I can think of no reason otherwise that it needs to be clocked.
If it is a straight fitting attached to a short enough hose that it wants to be aligned than you really need a swivel in there somewhere
anyway pics would help

 

[guythatbrews]

They make swivel elbows for pneumatic applications. I think they make hydraulic fittings with a locknut/oring that locks the fitting at any orientation.

Here is an explanation of G vs. R designation.

G or R or BSP

www.bola.de

 

[kb0thn]

Is it a right angle fitting? I can think of no reason otherwise that it needs to be clocked.

The two that have been causing me problems lately have been right angle fittings. I wanted this air inlet connection to be pointing down and the best I can get is 45 degrees.



But I also had the same problem on a non-right angle. The original air prep block series was discontinued by the OEM. I needed to re-use the pressure switch portion so i had to get that block in the middle of the rest of the blocks. I used short nipples with o-rings and really "reefed" on it.

They make swivel elbows for pneumatic applications. I think they make hydraulic fittings with a locknut/oring that locks the fitting at any orientation.

I have seen these in hydraulic applications. I'll have to see if I can find them in smaller sizes.

Thanks

 

[guythatbrews]

Should be easy to find the air fittings. They don't have the locknut but just shoulder up and swivel.

 

[Joe Henderson]

If it's a pipe thread you're SOL. If it's a straight thread you can clock it by carefully filing a little off the lead thread so it will start at a little different location.

 

[Nmbmxer]

Usually there is a jam nut on a hydraulic port fitting that isn’t a straight. The jam nut squeezes the oring between a washer, the fitting root diameter, and the chamfer on the port itself. This is a JIC example but they are all similar.

 

[gustafson]

For the right angle one get a bspp to jic swivel straight adapter, then right angle jic swivel. AN fittings might be easier/cheaper, they are interchangeable with JIC
Since it is just air, you could turn a nylon washer as a seal for one side of the straight connection to get it to be just what you want

 

[adamm]

Another option is to use R or BSPT fittings. In a lot of (Euro) industrial pneumatic systems, all of the female ports are straight (G or BSPP), and then you can use either straight or tapered male threads (R or BSPT). The thread form and pitch are the same between the two. You need sealant on the tapered threads like an NPT.

Or, typically those systems are for push-to-connect air. You can use a metal/plastic push-to-connect elbow, a short piece of tube, and then a push-to-connect to NPT straight fitting to screw your quick connect into.

Edit:
While looking for example fittings, I noticed Automation Direct has these stem adapters, so those look like they could replace the short bit of tubing after the push-to-connect elbow.

 

[kb0thn]

Another option is to use R or BSPT fittings. In a lot of (Euro) industrial pneumatic systems, all of the female ports are straight (G or BSPP), and then you can use either straight or tapered male threads (R or BSPT). The thread form and pitch are the same between the two. You need sealant on the tapered threads like an NPT.

That's actually a legitimate thing to do? I have seen that, but it has always appeared to be a maintenance man sort of thing. That little tidbit may be an "ahh ha" moment for me.

Thanks

 

[adamm]

That is the "official" Festo position. All of their devices are G ports, and they sell both R and G male fittings. They're a big outfit of high-quality products. I assume that is industry standard. We shipped hundreds and hundreds of ports worth of Festo valve banks with R fittings in G ports without issue.

 

[johnmontrose]

You know the thread pitch of the fitting. Make or buy some shim washers in 1/3 or 1/4 pitch thickness. Add one or two or three as necessary to clock the fitting.

 

[James H Clark]

I agree with JohnMontrose, use either nylon or fiber flat washers of the needed thickness to obtain the desired position.
JH

 

[boslab]

I’d just use festo push fit and the appropriate nylon tube , 5,6 8 or 12 or whatever , just a suggestion.
Clocking was usually done with a copper washer ,
Mark

 

[Bill D]

Clocking spark plugs is done with stacks of copper washers. I would assume for your use fully annealed. Should be re-annealed after each fit up.
Copper is easy to anneal. heat to red hot and let cool or quench.
Bill D

 

[idacal]

I have been dealing with BSPP fittings on a piece of equipment and was wondering if it some hack had been in there before, why some were tapered and some weren't. thank you, still its a totally new learning curve is there any place online to get the fittings reasonably priced, closer to jic prices? just ordered a 1.25 cap for a line, 40 dollars plus freight for 1 cap.

 

[Farmer Phil]

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[adamm]

I have been dealing with BSPP fittings on a piece of equipment and was wondering if it some hack had been in there before, why some were tapered and some weren't. thank you, still its a totally new learning curve is there any place online to get the fittings reasonably priced, closer to jic prices? just ordered a 1.25 cap for a line, 40 dollars plus freight for 1 cap.

When I worked for an automation company, we were exclusively Festo. They were reasonably priced, and easy to work with. When I left that company, I discovered that without being an OEM customer they are crazy expensive, and hard to deal with.

Since then, all the push-to-connect I've used have been from automationdirect (that I linked to in the earlier post) and McMaster. They seem decent. No better, no worse than the Festo fittings from what I've seen.

 

[ratbldr427]

They make a nut with a captured Teflon seal washer for NPT hydraulic fittings to clock them. I have some in stock. I don't know if they are available BSPP,BSPT. Go online and browse the Festo catalog , hard to believe they won't have what you need. Making washers is easy enough. Dealing with air plastic ,aluminum or copper will work. You know the pitch devide by 360 to find how thick to make the washers. I have to deal with this crap every now and then. But we are seeing less and less NPT since just about all our machines are now European.

 

[ratbldr427]

I am doing pneumatic maintenance and repair on a 2000 vintage German made CNC router. Pneumatic fittings are all BSPP which I understand to be a straight thread that requires an o-ring on the face to seal. I guess these are now called "G" thread, which Parker says stands for "global". Fittings are mostly 1/4" with some 3/8" and 1/8".

Question: How the heck are you supposed to put fittings together into a given orientation and have them compress the o-ring enough to seal? On some it magically lines up. On others I am 1/2 a rotation away from where I need to be by the time the bodies bottom out on the metal washer surrounding the o-ring. With putting the fragile looking part in a bench vise and using a 8" long wrench I can get another 3/8 of a turn tighter before things are *really* bottomed out and I am about to break something.

It appears that somebody before me dealt with this by using various thread sealants and goops on the threads like I would expect to see on tapered threads. They skipped the o-rings all together. Is this the right way?

Thanks,

-Jim

A little late but you may be able to find these in BSPP. That is for 1/4" NPT hydraulic Weatherhead which is now Danaher? They don't leak under hydraulic pressure. You might also look at SMC I think they have something for air like that.