The 5th edition and e-text are available now from McMaster University.

DETAIL ENGINEERING AND LAYOUT OF PIPING SYSTEMS - Edition 6
ISBN: 9780666386267

The scenic route is:

1.  http://campusstore.mcmaster.ca

2.  Click "Search for Textbooks" and complete drop down menu as follows:

             Step 1 Program: McMaster Undergrad and Graduate

             Step 2 Term: Ongoing

             Step 3 Department: ENGINEERING

             Step 4 Course Code: BOBWILSON

             Step 5 Section: DETAILENGINEERING

3.  Click "Find My Textbooks"

4.  Add desired items to cart and proceed to checkout

The new fifth edition is available in May 2018.