If satisfied as to the competency of an applicant the board shall issue a certificate to such applicant, authorizing him to engage in the business of installing sanitary plumbing and to install sanitary plumbing. The fee for the certificate to the master or employing plumber shall be five dollars and to journeymen plumbers the fee shall be two dollars. Such certificate shall be valid for the term of one year, but it may be renewed upon proper application to the board and payment of a fee of fifty cents.