As a starting point consult the Northwest Territories Boiler and Pressure Vessels Act R.S.N.W.T 1988, c.B-2 for useful information on pressure equipment exemptions and requirements. Always consult the chief inspector of a jurisdiction.
Northwest Territories Canadian Registration Numbers for fitting designs are issued by ACI Central who is the designated regulatory authority for seven provinces and territories that include: Newfoundland, Nunavut, Prince Edward Island, New Brunswick, Nova Scotia, North West Territories, Yukon. This small agency located on Prince Edward Island vastly simplifies what could be a terribly long and bureaucratic process of dealing with seven entities.
For boilers, pressure vessels, and pressure piping systems, you may also contact the Northwest Territories Government, Public Works Services, Boiler & Pressure Vessels site provides further information and useful contacts.