Cantilever Threaded Connection

Maximum deflection allowable isn't calculated, it's specified or determined by good practice, typically not more the 1/360 of the cantilever length.

To calculate actual deflection, I don't think the fact that it's threaded affects it. If the female part is fixed (as it must be for a cantilever) you can find deflection using the usual formula, including the I-value (2nd moment of area) of the pipe.

You haven't mentioned stress, but you also need to check that is OK. Highest bending moment is of course at the threaded connection and should use the actual pipe wall thickness, taking account of the threads.

I don't think the fact that it's threaded affects it.

???

The threaded section will effect it with the threads cut, reducing the wall thickness.

Yes, that's what I meant by "the actual pipe wall thickness, taking account of the threads." But as long as the stress at that point is OK, I don't think it significantly affects the total deflection at the end of the cantilever, which is determined by bending all along the length. The angular deflection is by definition zero at the fixed end of the cantilever, and the thread doesn't alter that (provided stress is acceptable).

with the exception of a stress point on the thread.....

Of course, that's why he needs to check stress based on the reduced thickness.

What is in the pipe, its temperature and its pressure?

What is the weight of the lagging and the cladding attached to it?

What is the specification of the pipe?

Why is this task not being delegated to a qualified Piping Designer at the facility?

Use a socket fitting and weld it.

Why is there a limit on a pipe cantilever, what is the function of this pipe? is it actually being used for a piping function?

I'll second that!

catradar - more detail on your set-up might help get a more useful answer.

The most liberal of structural codes allow L/180 for cantilevers and L/360 for simply supported beams and/or encastre beams. The European code allows for L/200 with a maximum of 10mm. However, no information thus far indicates that this application is a structural one.

if the deflection comes during the makeup, methinks you are in trouble, as allowable deflection would progress from 0-100% during that time period.

The maximum deflection for any cantilever system is described by the standard formulas for bending beams. In your case, it would be -Wlexp3/3EI, where W=load on the pipe, l=length of pipe, E=elastic modulus of the material, and I=moment of inertia around the axis of the pipe. It is safer to use this formula than to rely on rules of thumb, unless their origin is verifiable.

What you haven't mentioned is the pipe bore, or the thickness of the pipe wall. Further, if the cantilever is anchored by a female thread, then such thread is cut within a fitting (eg screwed socket/ other), not within the pipe itself.

Therefore the strain is taken up within the fitting, and the male thread of the mated cantilevered pipe. Bear in mind that the thickness of the pipe wall is diminished owing to the cutting of the thread, and if it is an NPT thread, there will be some play in the fitting due to the taper of the thread. Installation seems like a clever amateur design. I can't/ won't help without installation design drawings to refer to.