As a starting point consult the Manitoba C.C.S.M. c. S21- The Steam and Pressure Plants Act for useful information on pressure equipment exemptions and requirement(pressure vessel design course)s. Always consult the chief inspector of a jurisdiction.
Recently, Manitoba issued an exemption for certain categories of fittings that has very similar wording to the British Columbia exemption. Here is a link to the document.
The Manitoba office of the Fire Commission, Inspection and Technical Services Manitoba site provides information, forms and useful contacts.
Not unlike Quebec, Saskatchewan and BC certain categories of fittings are exempt from registration in British Columbia. The link to this is found here.