Minicraft 1/350 Titanic old version

You might want to check out the TRMA.  A gentleman by the name of Art Braunschweiger did just that on his 1/350 Minicraft kit and his steam pipes look outstanding (along with the rest of his model).  You can see his progress on the funnels here.

EDIT:  Here is the pipe bending post.

Mike

You might try using a soldering pen for a spot application of heat to bend the plastic.  Or, try replacing the plastic "water pipes" with copper wire of the appropriate diameter...

Good Luck

Ray