B-1.1, r. 2 - Construction Code

Full text
8.91. A swing joint connected during construction work on threaded steel underground piping must be connected with two 90 ° elbows and a nipple.
For that purpose, the use of the following is prohibited:
(1)  a male-female elbow,
(2)  a close fully-threaded nipple, and
(3)  a 45 ° elbow.
O.C. 220-2007, s. 1.