The BC Safety Authority grabbed that URL safetyauthority.ca, but that doesn’t mean that they cover all of Canada… only British Columbia BC oil and gas commission. At the time of writing this their website home page kind of also doesn’t make it clear that they are the regulators for (British Columbia) BC oil and gas commission, but hey, who are we to question why?
CSA B51 is pretty clear about the acceptability of reciprocal approvals from other jurisdictions of first registration, but the BC Safety Authority seems to be the only regulator that has created forms to do this and will seriously reciprocally register with very little trouble. The following page provides all the details.
Boiler Safety Orders, Directives, and Information Bulletins
Directives are interpretation of a regulation or code. Compliance is mandatory.
Not unlike Quebec, Saskatchewan & Manitoba certain categories of fittings are exempt from registration in British Columbia. The link to this is found here.