The UNI 2280 standard (now obsolete) concerned steel flanges for piping, mainly used in industrial and civil systems.
It was an Italian standard specifying the geometric, dimensional, and technical characteristics of flanges.

Characteristics of UNI 22-80/82/83/84 Flanges:

• The material is mainly carbon steel for general applications;
• Possibility of use also in alloy steels for high temperatures or special conditions;
• Nominal pressure ratings include PN 6, PN 10, PN 16, PN 25, PN 40;
• Nominal diameters range from DN 10 to DN 1,200. However, the most commonly used sizes, due to their lower thickness compared to EN standards, range from DN 600 to DN 1200.

The UNI 6091 standard (now obsolete) concerned steel flanges for piping, mainly used in industrial and civil systems.
It was an Italian standard specifying the geometric, dimensional, and technical characteristics of flanges.

Characteristics of UNI 60-91/92/93/94/95 Flanges:

• The application of blind weld flanges is for low-pressure piping;
• Materials for this type are carbon steel or stainless steel;
• Nominal pressure ratings include PN 6, PN 10, PN 16, PN 25, PN 40;
• Nominal diameters range from DN 10 to DN 2,000. However, the most commonly used sizes, due to their lower thickness compared to EN standards, range from DN 600 to DN 1600.

The UNI 2276 standard (now obsolete) concerned steel flanges for piping, mainly used in industrial and civil systems.
It was an Italian standard specifying the geometric, dimensional, and technical characteristics of flanges.

Characteristics of UNI 22-76/77/78 Flanges:

• Carbon steel flanges used in civil and industrial systems (water, air, steam, gas, etc.);
• Nominal pressure ratings include PN 6, PN 10, PN 16, PN 25, PN 40;
• Nominal diameters range from DN 10 to DN 2,000. However, the most commonly used sizes, due to their lower thickness compared to EN standards, range from DN 600 to DN 1600;
• Materials are generally unalloyed or low-alloy steels.