Wash. Admin. Code § 296-104-140
Upon completion of the installation, all boilers and unfired pressure vessels shall be inspected by an inspector as defined in WAC 296-104-100. At the time of this inspection, each boiler or unfired pressure vessel shall be marked with a serial number of the state of Washington followed by the letter "W." The marking should be conspicuously located and as close as possible to the boiler or unfired pressure vessel nameplate.
All boilers and unfired pressure vessels granted a Washington state special by the board of boiler rules shall have a serial number of the state of Washington followed by the letters "WS." This number shall be assigned by the chief inspector.
Washington numbers assigned by the chief inspector for historical boilers and pressure vessels from outside the jurisdiction shall be a serial number of the state of Washington followed by the letters "WH."
All rental boilers used in the state of Washington shall be marked with the serial number of the state of Washington followed by the letters "WR." This will indicate that the boiler is a rental unit.
The state of Washington markings, numbers and letters, referenced above, shall not be less than 5/16 inches in height and shall not be concealed by lagging or paint and shall be exposed at all times.
Wash. Admin. Code § 296-104-140
Statutory Authority: Chapter 70.79 RCW. 13-10-018, § 296-104-140, filed 4/23/13, effective 6/1/13; 04-21-069, § 296-104-140, filed 10/19/04, effective 1/1/05. Statutory Authority: RCW 70.79.030, 70.79.040, 70.79.150, 70.79.290, 70.79.330, 70.79.350, and chapter 70.79 RCW. 02-23-036, § 296-104-140, filed 11/13/02, effective 12/14/02. Statutory Authority: RCW 70.79.030 and 70.79.040. 99-22-026, § 296-104-140, filed 10/26/99, effective 11/26/99; 96-21-081, § 296-104-140, filed 10/16/96, effective 11/16/96; 95-19-058, § 296-104-140, filed 9/15/95, effective 10/16/95; Order 73-1, § 296-104-140, filed 3/22/73; Part III, § 9, filed 3/23/60.