(1) Where no petition for review is filed. In the event no petition for review is filed as provided herein by any party, the proposed decision and order of the industrial appeals judge shall be adopted by the board and become the decision and order of the board, and no appeal may be taken therefrom to the courts.

(2) Proposed decision and order deemed adopted without formal action. If an order adopting the proposed decision and order is not formally signed by the board on the day following the date the petition for review of the proposed decision and order is due, said proposed decision and order shall be deemed adopted by the board and become the decision and order of the board, and no appeal may be taken therefrom to the courts.

(3) Order adopting proposed decision and order—delay in mailing to parties. To permit adequate time for postal delivery of petitions for review or requests for extension of time to file petitions for review which have been filed by mail pursuant to RCW 51.52.104 and WAC 263-12-01501 (b)(ii), the board will delay the mailing of its order adopting the proposed decision and order to all parties until three days after the date the petition is due. Notwithstanding the date of mailing of the order adopting the proposed decision and order, such order shall be effective immediately following the last day permitted for filing a petition for review.

(4) Setting aside final order due to delayed postal delivery. If, after entry or mailing of the order adopting proposed decision and order, a petition for review or a request for extension of time to file a petition for review is received which bears evidence of mailing within the time permitted for filing such petition or request for extension, the board will set aside the order adopting the proposed decision and order and consider the petition or request for extension as one timely filed.