Installation of a threaded nipple with no wrench flats

i use these.

they are far superior to cam action internal wrenches..your plumbing wholesaler can order them for you...
http://www.whitlam-plumbpro.com/_detail.cfm?product_id=1695

Something...

...has to screw onto the other end of the close nipple. Use a wrench on that fitting or valve to tighten both it, and the close nipple. You can also usually use water-pump pliers to grab a close nipple right in the centre. Those are imperfect threads, and won't do any sealing anyway, so if they get dug up a little, it won't matter. Knipex pliers are great for this, as they've got much narrower jaws than other brands. They also grab like a pipe wrench - once they bite, you don't have to squeeze the handles. The Cobra models are the best - push button to change sizes, so the setting stays where you put it. Somebody here on the Wall put me onto these things about a year ago. They cost more, but they're easily worth it. If you try these, you won't go back to whatever you're using now.