To hear and decide appeal claims, the Commission shall appoint one or more impartial appeal tribunals consisting in each case of either a referee, selected in accordance with Section 41-29-70, or a body consisting of three members, one of whom shall be a referee, who shall serve as chairman, one of whom shall be a representative of employers and the other of whom shall be a representative of employees. Each of the latter two members shall serve at the pleasure of the Commission and be paid a per diem as fixed in the annual State appropriation act for boards, commissions and committees for each day of active service on such tribunal plus necessary expenses, as likewise fixed in the annual appropriation act. No person shall participate on behalf of the Commission in any case in which he is an interested party. The Commission may designate alternates to serve in the absence or disqualification of any member of an appeal tribunal. The chairman shall act alone in the absence or disqualification of any other member and his alternate. In no case shall the hearings proceed unless the chairman of the appeal tribunal is present.