Possible FAC, possible weld failure

[KarlwithaK]

A leak developed on a weld at my station.
What we have is a 52" horizontal run of High Pressure Turbine Extraction Steam piping. At the bottom of the line is welded a 12x12x4 tee. The Tee is vertical, one 12" end welded to the invert of the 52", the other reduced to 2" for a manual drain valve. The 4" branch is horizontal, gravity pitched and runs to the main condenser. (under vacuum)The purpose of the line you probably guessed is to remove condensate from the line during start-up and Cool-down and any collected entrained condensate in the HP Turbine exhaust.
What we have for a leak is manifested as multiple pinhole leaks in the TOP 1/4 of circumference of the weld joining the 123x12x4 tee and the 4" horizontal run to condenser.

What sorts of failure modes would fail this weld at the top? I am currently waiting for NDE/UT inspection reports. This does not sound like FAC modes I am familiar with. See attached sketch.

Also, I used to have a cute little handbook with nice color photos of many examples of FAC found in typical suspect locations. Can anyone recommend a text, handbook or online source of outside symptoms as observed and then cut-pipe photos showing the causes? Maybe with example UT maps, too?

 

[LittleInch]

Have you read this paper attached?

Also please post your sketch in pdf. Not many people have visio.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[KarlwithaK]

Just received photos from the field, attached. The verbal report from the NDE tech indicated FAC-similar rippling inside the 4" for about 1 1/2 pipe diameters. and concentrated in the upper quadrant of the ID.

 

[KarlwithaK]

And another shot.
And thanks to LittleInch for a speedy reply. I had not seen the interesting report, and it may affect decisions where we have been using P33 cromoly for replacements. The piping is still good, but it may not help the HAZ of the weld.