Bastard Flanges??? 2

[miningman]

I need to install 16 inch line, class 300, with two "interesting" engineereed changes in line direction. At each location, the line is to be given a change in azimuth of approx l3 degress, as well as a change in slope of approx 3%. Governing code is B31.3.

I cant see any way of doing this without some field fitting/ welding. Are there bastard flanges available to facilitate this type of exercise or do the welders have to use their ingenuity??

This is probably a no brainer for experienced pipers but its a bit new to me. Thanks in advance.

 

[spayette]

These type of problems are difficult to comment on without seeing a drawing and knowing all of the particulars of the design. However, lacking the preceding, one alternative is to use a 90 or 45 degree ell and trim it to the appropriate angle and weld it into place. The trimmed fitting, when installed, would be "rolled" to match the 3% slope. Calculating the trim angle is a slightly tricky geometry problem or get a piping designer to lay it all out in AutoCad and then read the required dimensions electronically.

 

[unclesyd]

You can work this out as a rolling offset.
You could use a Long Radius Elbow to cut your odd angle. I haven't laid it out but you could possibly get three elbow from one LR elbow.

Here is one of several books out there that have the information on how to do this.

http://www.pipefitter.com/existing_php/PTPM.php

Several other books.

http://www.pipefitter.com/dolphincart/category.php?cat=Cat0001

 

[11echo]

I worked at a small refinery that did "interesting" things with blind flanges. IF we had an off set of a few degrees sometimes we'd get a blind flange and send it to the shop to be machined with an angled hole. SO basically we are making a slip-on flange with an angled bore! This works really well for all the slight off-sets ...looked like hell, but worked! Good Luck!

 

[miningman]

Echo., would i expect any grief from mt QA/QC people if I did this??..... B31.1 is the relevant code.

 

[MJCronin]

Echo...

"Intersting things" done with blind flanges in ASME B31.1 systems have been addressed in the B31.1 Code Cases

The angled hole through the face of a blind flange is not permitted.

-MJC