Help identify casing hanger threads

[Philrock]

I'm reverse engineering an 11" 3,000 lb. casing hanger, and would appreciate some help identifying the tapered threads at the ends of the fitting. The threads have a 5.545" diameter x .55" deep lead-in recess, and the threads are about 3.4" long. I have been told that they 8-Round threads.

I went through a 2010 version of API 5B, and was not able to find a thread as large as the one in the part I'm working with.

Any help identifying these threads so I can put the proper callout on the drawing would be appreciated.

 

[Philrock]

Never mind - I found it in API 5B - it's called "casing long thread."