Back to Industry News2026-09-12

What are the pressure classes for flanges?

Important note: Class and PN cannot be simply converted as equivalent values. The allowable pressure rating of a flange decreases as temperature rises.

ASME B16.5 — American Standard (Class / LB Rating)

Most widely used globally for oil, gas and chemical industries. Common classes: Class 150, 300, 400, 600, 900, 1500, 2500 (also referred to as 150LB, 300LB, etc.).

Class 150 — Low pressure, for water, air and general pipelines
Class 300 — Medium pressure, for steam and ordinary process pipelines
Class 600 — High pressure, for oil & gas and high-temperature process pipelines
Class 900 / 1500 / 2500 — Ultra-high pressure, wellhead, hydrogen service and severe operating conditions

EN 1092-1 / HG / GB — European & Chinese National Standards (PN Series)

Nominal pressure in bar. Common classes: PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160.

PN6 / PN10 — Atmospheric water supply and drainage
PN16 — Most common for low-pressure pipelines
PN25 / PN40 — Medium-pressure process and steam service
PN63 / PN100 / PN160 — High-pressure applications

JIS B2220 — Japanese Standard (K Rating)

Common classes: 5K, 10K, 16K, 20K, 30K, 40K, 63K.

GOST 33259 — Russian / CIS Standard (PN Series)

Common classes: PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN200.

KS B1503 — Korean Standard

Adopts PN system: PN10, PN16, PN25, PN40, PN63, PN100.