No examination shall be required of any applicant for a certificate of competency who, on July 16, 1973, was engaged in a bona fide business or trade of plumbing, or on said date held a valid journey level plumber's license issued by a political subdivision of the state of Washington and whose license is valid at the time of making his or her application for said certificate. Applicants qualifying under this section shall be issued a certificate by the department upon making an application as provided in RCW 18.106.030 and paying the fee required under RCW 18.106.050: PROVIDED, That no applicant under this section shall be required to furnish such evidence as required by RCW 18.106.030.