Strength of Conical Thread?

Hi JuzerNejm101,

This is a Metric Conical Thread (we use the term Metric Taper Thread) used mainly in Germany.

It is used for pressure applications on pipework, is this your application?

If it is you, would be better to consider using a parallel thread.

If you must use a taper thread may I suggest you consider BSPT (British Standard Pipe Taper) or for the USA NPT (National Pipe Taper).

This is not a definitive answer but something for you to consider with regards to your application.

The more information you can give on your application the greater the help this forum will be able to give.

Best regards,

John

Thx for the reply.

I'm familiar with the use of the thread.
What I'm trying to find/do, but had no luck into doing so is how to calculate if the tapered thread (with its limited length) can be used in my design.
The information I got are the axial force on the bolt and the material.

Hi JuzerNejm101,

Try putting "tensile strength of threads" into Google. There are several answers, one of which might be of help.

Best regards,

John

Have been running through it. But don't know if this applies on tapered threads the same way as on parallel threads.

I don't know if this will help at all, but: Techfacts. This is oil well stuff.

A tapered thread gains by coming to a very close tolerance, so you might try adding up each thread as if it was part of a precision assembly of the same but constant diameter. Usually, only one or two threads take most of the load, due to the difference in elasticity between the male and female parts. To get the lightest, smallest parts, you taper the thickness of the material backing up the threads so that each thread carries the same load. A drawing of a cross-section of the thread and parts can be analyzed by FEA if you have it available, or guesstimated reasonably well.

Taper Threads (or Pipe Threads) are used when you want to seal against fluids and not have leaks. Used in drain plugs, half couplings, lubrication lines, pipes etc.

If your requirement is strength, you will have to use straight threads, preferably fine pitch and high tensile alloy steels, suitably heat treated.

You can find innumerable literature, to calculate the different types of strength rating for threads including Machinery's Handbook for example