ASME Designator (U, U2, …) must appear directly below the ASME Certification Mark, however it may be printed rather than stamped on nameplate.

What is the ASME Certification mark?

The ASME Single Certification Mark (The MARK) is the international mark of safety and quality. Companies that use parts and products with The MARK communicate their commitment to the highest levels of public safety and quality. That’s why businesses and regulators around the world “Demand The Mark.” The MARK is recognition that the manufacturer has followed all aspects of the applicable ASME code or standard, and met the rigorous requirements of ASME’s Conformity Assessment certification program. 

ASME Designators

An ASME U stamp certifies that a manufacturer has met the quality control requirements laid out by the ASME Boiler and Vessel Code, specifically Section VIII Division 1. If other ASME codes have been applied, other designators are binding. A manufacturer who uses different ASME codes can also use different designations. The following tables provides an overview:

Table 1: Power Boilers

Designator	Products	Applied ASME Code
S	Power Boilers	Section I
A	Assembly of Power Boilers	Section I
E	Electric Boilers	Section I
M	Miniature Boiler	Section I
PP	Pressure Piping	Section I
PRT	Parts Fabrication	Section I

Table 2: Pressure Vessels

Designator	Products	Applied ASME Code
U	Pressure Vessels	Section VIII Division 1
UM	Miniature Pressure Vessels	Section VIII Division 1
PRT	Parts Fabrication	Section VIII Division 1
U2	Pressure Vessels (Alternative Rules for Pressure Vessels)	Section VIII Division 2
U3	High Pressure Vessels	Section VIII Division 3

Table 3: Heating Boilers

Designator	Products	Applied ASME Code
H	Heating Boilers/Cast Iron Sectional Heating Boiler	Section IV
HLW	Lined Potable Water	Section IV
PRT	Parts Fabrication	Section IV

Table 4: Reinforced Plastic Vessels

Designator	Products	Applied ASME Code
RP	Fiber-Reinforced Plastic Vessels	Section X

Table 5: Transport Tanks

Designator	Products	Applied ASME Code
T	Transport Tanks	Section XII
PRT	Parts Fabrication	Section XII

Table 6: Pressure Relief Device

Designator	Products	Applied ASME Code
V	Boiler Pressure Relief Valves	Section XIII
HV	Heating Boiler Safety Valves	Section XIII
UV	Pressure Vessel Pressure Relief Valves	Section XIII
UD	Pressure Vessel Pressure Relief Devices	Section XIII
UV3	High Pressure Vessel Pressure Relief Valves	Section XIII
UD3	High Pressure Vessel Pressure Relief Devices	Section XIII
TV	Transport Tanks Pressure Relief Valves	Section XIII
TD	Transport Tanks Pressure Relief Devices	Section XIII

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What sizes do the ASME Certification Marks Stamps come in?