As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - IN-FLIGHT YVR-DFW - CREW REPORTED AIRCRAFT COULD NOT MAINTAIN PRESSURE. CABIN OXYGEN MASKS WERE DEPLOYED. EMERGENCY DECLARED DIVERTED SEA LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. DUE TO REPEATS OF PRESSURIZATION PROBLEMS AIRCRAFT WAS FERRIED TO TUL FOR MAINTENANCE. AT TUL REPLACED RIGHT PACK FLOW CONTROL VALVE. SYSTEM GROUND CHECKED NORMAL OPERATION.