I recommend doing a swing-joint with funny pipe.here's one pre-assembled:Yeah. My Ts off the main pipe are with (welded) slip joints on both ends and threaded at the top. Put in a threaded funny pipe elbox, run the funny pipe about a foot or so (more if location dictates), put another threaded funny pipe elbow, and then screw the sprinkler head into that.Slip/slip/threaded Thttp://www.mscdirect.com/product/details/36998615?src=pla&am...funny pipe elbow at each end of the funny pipehttp://www.newegg.com/Product/Product.aspx?gclid=CjwKEAjwjN2...Those probably aren't the correct size, just an illustration of all you need to connect the sprinkler heads.After installing the system I realized I had to relocate one of the sprinkler heads by several feet. Rather than dig up the main line, I just put a LONG funny pipe extension on it and trenched that in. Much easier, although the next guy who tries to figure out where the main line runs will probably scratch his head.I did buy a trenching shovel, but never had to use it. I just made sure to dig the Ditch Witch trench deep enough. One thing I learned: the depth of the inflexible pvc pipe run will be determined by the shallowest points. And a swing joint allows the swing-arm to be mostly parallel to the irrigation pipe, so you don't need to trench off to the side.I guess I don't understand this, or don't understand why it's important. The funny pipe allows you to put the sprinkler head somewhere other than directly above the main pipe. If it's a foot away - and buried - who cares if the pipe is parallel or perpendicular?And upthread somebody mentioned replacing sprinkler heads: I just take a shovel, slice a circle around the head about 4" out, then "pry up" some dirt clods until I have freed the head. Twist it off the funny pipe connector (usually takes a big channel-lok wrench since it's been sitting in the mud for 6 years). Twist the new one on (by hand), place the divots as best I can, tamp down with my foot, throw a little grass seed down (if necessary), done.As I mentioned, I used the impact type sprinklers all over when I installed the system, because they were cheaper by a couple bucks each. Mistake. Within a few years the cavities in the base had accumulated dirt, crud, grass, etc. and I had to replace them all. I started doing it one at a time as they went bad, but finally bit the bullet and did them all, 15 in all. (Many of the zones were sprayer heads, not impact sprinklers. I've had no trouble with the gear driven ones, except one which a contractor thoughtfully ran over with a Bob Cat he was unloading to work on the neighbor's lawn. Thanks for that.