code for boring (machining) fittings from a sch to a sch ?

[Division]

Is there a code for this. We have a WPB B16.9 16" 90` Elbows which have been bored from sch 80 to sch 40.
The angel of the taper bore is 39, which in my opinion is to great for the flow.

A colleague think that the angle of the taper bore shall be 17,5 and another think there is a relations between the wall thickness which is 1:4.
But no one knows where to find these information, they just know it...

Is this covered in any standard (norm) ?

 

[jay165]

I've typically seen a 4:1 ratio called out on details. You may want to check whichever ANSI or ASME code you are using.

 

[unclesyd]

Go with "jay165". The less stress riser you have the better because someone is always got to get the load to elbow. The better the transition the better inspection now and later on.

 

[platvoet]

We apply a minimum angle of 8 degree, a maximum of 30 degree and an preferred angle of 14 degree. Design basis: ASME piping code and ANSI/ASME fitting standards

 

[PipMec]

Hi,

A plate (say A105) with a tappered bore (1/2&quot is to be installed between a pair of flanges.

The logical thing is to use a plate with a thickness per ASME B16.36 (orifice flanges) for the corresponding flange pressure class. And then make the bore to the required size.

Is there any reference to use for the calculations of the thickness?

 

[bvi]

The ASME B31 piping codes provide specific requirements for taper wall transitions such as this. They also refer to ASME B16.25 requirements.