ASME Code Welding

R-Stamp

The National Board offers the Certificate of Authorization and R symbol stamp for the repair and/or alteration of boilers, pressure vessels, and other pressure-retaining items. Requirements are described in NB-415, Accreditation of R Repair Organizations.

U-Stamp

Provides requirements applicable to the design, fabrication, inspection, testing and certification of pressure vessels operating at either internal or external pressures exceeding 15 psig. Specific requirements apply to several classes of material used in pressure vessel construction, and also to fabrication methods such as welding, forging and brazing. It contains mandatory and non-mandatory appendices detailing supplementary design criteria, nondestructive examination and inspection acceptance standards.

S-Stamp

Applicable to boilers in which steam or other vapor is generated at pressures exceeding 15 psig, and high temperature water boilers intended for operation at pressures exceeding 160 psig and/or temperatures exceeding 250 degrees Fahrenheit. Superheaters, economizers and other pressure parts connected directly to the boiler without intervening valves are considered as part of the scope of Section I.