1. Any person who intends to modify or repair a boiler, pressure vessel or portable gas container shall cause such modification or repair to be carried out under the supervision of an approved inspection authority, as contemplated in regulation 17(1)(b).
2. Any modifier or repairer carrying out any modification or repair, as contemplated in subregulation (1), shall issue a certificate in which the extent of the modification or repair is described and certify that such work is in accordance with a health and safety standard incorporated into these regulations: Provided that such certificate shall be countersigned by the approved inspection authority as evidence that the design of such modification or repair has been verified and that it has been modified or repaired and tested under their supervision in accordance with the said health and safety standard.
3. Whenever it appears from an inspection or test that a boiler or pressure vessel cannot be used with safety at its maximum permissible operating pressure and the user declines to have the necessary renewals or repairs effected, the user shall ensure that:
a. an approved inspection authority fixes a new reduced maximum permissible operating pressure; and
b. that the boiler or pressure vessel is not used at a pressure higher than the new reduced pressure.
4. The user shall cause the reduced maximum permissible operating pressure as calculated under subregulation (3)(a) to be marked on the manufacturer's plate on which the approved inspection authority shall also place its mark and no user shall thereafter require or permit such a boiler or pressure vessel to be used at a pressure higher than such a reduced pressure: Provided that in the case of a boiler the registration certificate together with a copy of the approved inspection authority's report shall be forwarded to the provincial director for correction.