(Amended by Ordinance Nos. 168183 and 176955, effective October 9, 2002.)  All plumbing work shall be performed either by an owner or by a journeyman plumber holding a valid certificate of competency from the State of Oregon, or a registered and indentured apprentice.  All journeyman plumbers while engaged in plumbing work shall carry with them their Oregon State Certificate of Competency.  All apprentice plumbers shall carry with them their apprentice registration cards and shall produce same at the request of the Plumbing Inspector of the Portland Bureau of Development Services.  It shall be the duty of the Plumbing Inspector of the Bureau of Development Services to require the journeyman plumber and apprentice plumber to show their registration card.