titanium pipe, open root vs. fused root

I have been asked to perform a 6G 4" titanium weld test. The trouble is there has been some questions raised about what to do for the root weld. We have discovered that if the root is fused it is a cleaner weld vs an open root. The question is weather this is an acceptable practice for a destruction test. When we tried to use the open root method it seemed to draw way to much oxygen into the affected area and ruin the weld.

---------------------------------------------------

Another option is a consumable insert.

inserts are commonly used for orbital welding but are also used a lot in pipe welding open butt joints and will allow for welding without a gap that draws in oxygen.

you could actually make your own by rolling some welding wire and tack welding it in to fill the gap.