Quality seems suspect if you zoom in. branches look like fillet welds, undercut and arc strikes?

I guess you better weld them in the right sequence to make access easier lol

That looks like a header going somewhere inside a boiler that's probably going to be a decent sized one about 600MW or more in capacity... Where the stubs are being lined up and prepped will eventually be welded to water wall tubes, risers and some down comers which will also be welded on to the economizer also inside a power boiler... Some of the welds will have to be mirror welded as I have done countless times in the past... It's a whole lot easier to do when it's new construction and yes! The welds do look shoddy to say the least!!! :( :( :(  It could be the main header, but without any drawings, I can only guess but, it's more likely one of many headers which will be placed on one of the many levels that make up a power boiler. ;)

Look in here on page 8 of 16 to see what a steam/water circulation system in a power boiler looks like, and where this headr may or may not be eventually positioned within the boiler itself:   http://www.swcc.gov.sa/files%5Cassets%5CResearch%5CTechnical%20Papers%5CCorrosion/INVESTIGATION%20ON%20THE%20FAILURE%20OF%20BOILER%20No%201%20ECONOMIZER%20TUBES.pdf

The material of the heavy walled pipe of the header itself could be aP-11, P-22 or P-91 material, or something else all together, but it all depends on the pressure rating for the header since most heavy walled headers operate on the high side of up to 3000 psig, and this is all dependent on the generating capacity of the power plant, so I'm just guessing from a visual without any specs available for me to review. It is definitely part of a power boiler being constructed somewhere in the world, and that I'll definitely bet on!!! :) :) :)

Here's an article on the condition assessment of Boiler piping and Header components by Babcock Borsig Power:

http://www.babcockpower.com/pdf/rst-164.pdf

Here's another interesting article also:

http://www.babcockpower.com/pdf/rst-143.pdf

There are a whole boat load of interesting articles and papers on all sort of situations regarding utility boilers which some folks in here may find interesting if they were to start at this link first:

http://www.babcockpower.com/index.php?option=techpapers&coid=&topid=2&sort=bypline

As well as this one too;

http://www.babcockpower.com/index.php?option=news&Itemid=56

And I cannot forget to include this one as well:

http://www.babcockpower.com/pdf/rst-129.pdf

Respectfully,
Henry