Monday Mutant 46: Danny Boy's Pipes

Place a piece of pipe in each square of the grid. Each pipe piece consists of two or more pipe sections which connect that piece to some or all of the squares which share an edge with the piece. Thus, there are four different shapes for a pipe piece: two sections at an angle (an L-bend), two sections in a line (an I-straight), three sections in a T-junction, and four sections in an X-junction. All of the pipe pieces must form a single connected unit, and there may not be any loose ends (if one piece has a section connecting to an adjacent square, the piece in that square must also have a section connecting back). Letters in a square represent the shapes (L-bend, I-straight, T-junction, X-junction) of all of the pieces which are connected to the piece on that square. (See here for an illustrated example.)