NPT , NPTF And Metric

I think NPT is some daft American thread and F stand for Fine...
Del

daft is that like BSP

No, it's no where near as daft as BSP.
Ever tried to work out the diameter of a 1/2" BSP thread?
Del

No have enough problems keeping up with the variances between them all. With equipment here coming from all over the world.

Only on parallel. It's not worth trying on taper.....

There is no such thing as a metric pipe thread.

http://en.wikipedia.org/wiki/ISO_metric_screw_thread

Shhhh. Don't say that, you'll only encourage someone to come up with one.
Del

In NPTF threads, the F stands for fuel.Also known as American Dryseal threads.
Careful measurement, or a thread gauges can be used to identify different threads.

The NPTF thread form has a sharp crest on the threads, which "bites" into the female part without need for joint compounds.

I have found that if you dope the threads on both parts with JB weld before assembling it doesn't matter what the thread pitches are or if they even match.

IF that don't seal it then welding a brazing usually does!

There is a fine thread standard both in English and Metric system. It was meant for fine instruments. I saw them, in equipment older than 1940. I have one or two in my basement. Other than that, no.

The pipe thread (in Eruope known as Whitworth) is a bastard shallow thread with conical aspects. Please do not even mention it in polite company, outside of piping, where it is quite useful.

if you have in your hand cable gland or tube fitting one 1/2"NPT and 1/2"NPTF and M20 how to distinguish between them?

In the world of tube fittings, the 'P' in NPT is for 'pipe', and 'F' is for 'female'.

The cable gland is an electrical fitting, not a pipe....this will be M20 thread (metric 20mm)

If the original poster manages to fit a metric cable gland into the socket for an NPT pipe fitting, it will be a world first! Anyone selling tickets?

In the world of tube fittings, there is no pipe.

The F does not stand for female in any case.

In the world of tube fittings, there is no pipe.

Well of course there is....instrumentation tubing and associated compression fittings. eg 1/2"NPT male -1/2" tube. This is a typical pipe-to-tube connector, installed by the tens of millions in process and petrochem plants everywhere, in many sizes and variations. These variations are available in other threads as well, including , BSPP(A&B), BSPT and Metric, and even combinations eg ISO to NPT.

does not stand for female in any case.

Technically, that is quite correct.....however, see the OP's confusion. It appears to me that the OP is a 'consumer' rather than an engineer. Common among many consumers is to abbreviate (eg when drawing up inventory or BOM's) from NPT Female to NPTF. That's why I answered 'in the world of'.......I have never seen or been offered a NPTF threaded compression fitting in several decades of experience. On the bright side, I think the OP understood my answer....

You're right. Your explanation is a very good one for the casual user.

Unfortunately, I used to run an engineering department that produced process and instrumentation piping drawings, that went into the equipment we built. The need for specificity in the identification of parts was real.

And, I'm just gettin' particular in my old age.

Particular is good...

And, I'm just gettin' particular peculiar in my old age.

NPT-Stands for National Pipe Thread

NPTF-Stands for National Pipe Thread-Fine (thread....)

As perscribed-it is good only for pipes - not tubes !! (by definition)

As so the OD for 1/2" pipe is:21.30mm (not 12.7mm !!)

Milimetric tubes/pipes - M20 means OD=20.0mm....

Outer diameters doesn't fit !! You have to produce a special connection

Better to look for another type of Female...

Sir,

In the USA, for the smaller sizes of pipe, the given dimension is the nominal ID, not the OD. The switch to OD dimensions is somewhere around 8". I had an interesting conversation one day when I was wiring up some equipment in Jamaica and went to the wholesaler to ask for some pipe. The reply was a question--"Do you want American thread, English thread, or Metric?" All were threaded, but the first was inches ID, the second inches OD, and the third metric, and none interchangeable.

--JMM

Dear JMM

Was quite astonished by your statement,rechecked again the API,ASTM+N.P.T. Standards,and found that your statement is mistake (please don't depend on Jamaican wholesaler...) It is just the opposite!! i.e. the Otside Diameter is merged with the Nominal Diameter,on: 14.0"!!!! and above!! . Smaller Otside Diameters are bigger and with very important reason: the fluid flow restriction is imperative in these diameters!!As so the Outer Diameter is higher,for threading / welding possibilities. If you look in the BSP Schedule Tables you should compile that the Scd 160 wall thickness- gives the inner diameter exactly as the Nominal size!!

It is not so with the Metric system!!

Sir,

Thanks for checking the size where US pipe dimensions change from ID to OD. The size I was needing in Jamaica was 3/4" or 1", so I think my post was valid. Did API, ASTM, or others give you any reference to English Thread standards as compared to NPT standards?

--JMM

Dear JMueller

Ofcourse there id the BSP (British Stanadard Pipe) with Withworth pipe threads

Type: BS.21 / DIN-2999

THEY HAVE THE SAME NOMINAL Outer Diameter like NPT (EXCEPT:2.5" pipes)

Best Regards Klepatch

There are also straight pipe threads that are use in electrical conduit connections. Same thread size and pitch but no taper for the seal.

Yep, called NPSM for National Pipe Straight Machine.

That is why they sell rubber hoses and clamps.

Don't know if it is technically a "standard", but the Pharma industry (yes, threads do enter into utility services - all is not sanitary clamped) denotes female and male threads in a Bill of Material by adding the letter ahead of the NPT. Thus we typically may have a 1/2" MNPT for a 1/2" standard pipe thread male, or 3/4" FNPT for a female in 3/4".

As others have noted the "F" after is fine thread.

"As others have noted the "F" after is fine thread."

Should read, "As others have noted, incorrectly, the "F" after is fine thread."

Your right - "Fuel" Sorry. Never use these in my work.

Let's put this to bed. The point was to assist the OP after all....

While I have actually seen such a reference (FNPT) in the world of tube fittings ... here is an excerpt from possibly the largest global manufacturers catalog.

DBZ - NPT FEMALE ELBOW-FRACTIONAL TUBE

http://www.parker.com/portal/site/PARKER/menuitem.de7b26ee6a659c147cf26710237ad1ca/?vgnextoid=fcc9b5bbec622110VgnVCM10000032a71dacRCRD&vgnextfmt=EN&vgnextdiv=687516&vgnextcatid=1206&vgnextcat=DBZ%20-%20NPT%20FEMALE%20ELBOW-FRACTIONAL%20TUBE

Doesn't matter. The OP has been long gone for a while, I'm sure.

So am I.

Cheers.