Machined Thread in 6" Fasteners?

[bmoorthy]

Hello All

Is it mandatory that the threads in a Stud (6" Dia) is required to be only rolled. Is Machining in CNC machine (Lathe)by cutting tool permitted.

If the manufacturer suggests machining then is it OK.

Is there any prohibition in ANSI/ASME B 1.1 or B 18.2 in this regard.

The Studs are being used in ASME Sec VIII Div 2 vessels and Div 1 Vessels.

 

[unclesyd]

I don't have current copies of the standards that you mention so I'll have to defer to someone else whether there is any stipulation on thread forming in the latest publications of said standards.

From the supply side currently all studs of this size are called out as single point threads. Not all are 60°point as there are some special thread profiles called out by certain end users.
The largest stud currently available with rolled threads is 4" and it an expensive special.

Just a little reminder that you are in a new world when it come to properly tighteneing fasteners of this diameter.

 

[studbolt]

My company has recently rolled threads M110 -6mm pitch on
high tensile steel bars 10 Metres long. Awesome sight, 700 kgs+ per stud! - client is using the studs in a bridge construction and the follow up may be M125 -6mm pitch!
So it can be done.

 

[MintJulep]

ASME B1.1 defines geometry of the thread form. It does not discuss the method of manufacture.

None of the B 18.2 series deals with studs.

IFI-136 appears to allow either rolled or "threads produced by other methods" in some sections. However, in the section dealing with threads for "Pressure-Temperature Piping" the method of manufacture is not discussed. That section also refers to ASME B16.5, which I do not have ready access to.