U Stamps

There are no hard and fast rules, because special circumstances/design rules can be invoked, but in general:

• U {Div 1}: 15 psig - 3000 psig [may go higher with additional rules, see U-1(d)]
• U2: 15 psig - no stated limit [see 1.2.2.1 for requirements; above 10,000 psig U3 should be considered]
• U3: generally above 10,000 psig [again, this is just a "guideline", may be used at lower pressures as well]