Any owner or user may apply to the director for a rule or order for a variance from the standards, rules, regulations, or requirements of this article, upon providing such information as prescribed by the director. The director shall issue such rule or order if he determines that the proponent of the variance has demonstrated that the construction, installation, and operation of the boiler or pressure vessel will be as safe as if the standards, rules, regulations, or requirements were complied with. The rule or order so issued shall prescribe the construction, installation, operation, maintenance, and repair conditions that the owner or user must maintain. Such a rule or order may be modified or revoked upon application by an owner or user or by the director on his own motion at any time after six months from its issuance.