Appendix 2, Figure 2-4 (6): Weldneck Hub Length

[pogoGo]

I'm trying to determine what to take my hub length as per Section VIII - Division 1 - Appendix 2. In this case, my weldneck will have a 1:3 tapered hub that extends down to match the pipe diameter and then continues with a weld stinger, as shown in Figure 2-4 (6a). However, since the tapered hub slope does not exceed 1:3, I'm inclined to look at (6) but the hub length (h) there seems to be to the end of the weld.

1. For a 1:3 slope, am I supposed to take the hub length (h) to the end of the tapered hub as in (6a), to the end of the flange, or to where the weld ends as in (6)?

2. If the hub length is to be per (6a), for a 1:3 slope would the stinger length still have the 1.5*go requirement or would the hub length have the 1.5*go requirement?

I'm inclined to take the hub length (>= 1.5*go) to the end of the flange, making the hub length comprise of a 1:3 slope and the weld stinger.

 

[SnTMan]

pogoGo, why not just design per one of the figures? Eliminate all the guesswork?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[pogoGo]

SnTMan,

Moving forward that makes sense. I don't see how anyone could tell me I can't do that.

However, this flange is already made. I'm trying to supply the calculations which, in addition to the stress checks, also include the geometry checks.

 

[SnTMan]

Sounds kinda backwards to me. But a dimensioned sketch of your hub and any corrosion allowance would be helpful.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[pogoGo]

It's essentially Figure 2-4 (6a) just with a 1:3 slope on the hub and a shorter stinger length. No corrosion allowance. I've attached a sketch.

 

[SnTMan]

Well, since the slope does not exceed 1:3, I think you would be bound by Fig (6). Dimension h would be such as to exclude the stinger, and hopefully, would meet h >= to 1.5 go. This would at least be easily defensible. Any other interpretation, not so much IMO.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[pennpiper]

This sounds like a school class assignment. It that correct?

If not, why are you trying to "design a flange"?
Why don't you buy a ready made flange (from a supply house) in a material compatible for your service and in the proper size and class rating for the system?
I would predict that a "Custom" made Flange, to your special dimensions would be three times the cost of any off-the-shelf ready made flange.

"Why reinvent the wheel?"

Sometimes its possible to do all the right things and still get bad results