NCA-3856 (c) states " Identification marking shalll be transferred to all pieces when material or source material divided.
Also read NCA-3856.2 and NCA-3856.3
Lee
The following are exempt from stamping
Hot water heating boiler operated at a pressure not in excess of 30 psig and having a rating not in excess of 200,000 B.T.U per hour.
Hot water supply boiler boiler that are directly fired with oil, gas or electricity when none of the following...