Code Stamps held by Popham Mechanical Contractors, Inc.

Power Boilers (over 15 psi steam, 160 psi water, and temperature exceeding 250F) shall be stamped ASME (S) and National Boiler (N.B.). The “S” stamp by virtue of its description also covers the “PP” area or pressure piping. Super heaters, economizers, and other pressure parts connected directly to the boiler without intervening valves are considered as part of this scope.

ASME UPressure Vessels fabrication or weld modifications of unfired pressure vessels require the ASME “U” Stamp and National Board Stamp. These rules have been formulated on the basis of design principles and construction practices applicable to vessels designed for pressures up to 3000 psi.


R Stamp
Repair Certificate of Authorization and “R” stamp, from The National Board of Boiler & Pressure Vessel Inspectors, for the repair and/or alteration of boilers, pressure vessels, and other pressure-retaining items. Detailed requirements are included in the current edition of the National Board Inspection Code (NB_23).