Flange Standards Comparison: ANSI/ASME vs DIN vs PN vs JIS

By Feiyu Flange Technical Team  |  Updated August 2026  |  Reading time: 9 min

If you buy flanges internationally, you will meet at least three different standards: ANSI/ASME, DIN and JIS, plus the PN pressure rating system used across Europe and much of Asia. They are not interchangeable, and mismatching them is one of the most common causes of leakage and rework. This guide explains how each system works and how to avoid costly mistakes.

1. The four main flange systems at a glance

2. ANSI/ASME flanges: pressure class, not pressure

In the ANSI/ASME B16.5 system, the rating is a Pressure Class (150, 300, 600, 900, 1500, 2500 lb). The number is not the actual working pressure — the maximum allowable pressure decreases as temperature rises. For example, a Class 150 flange might allow ~285 psi at ambient temperature but far less at 400°C. Always check the pressure–temperature chart.

Common dimensions you must specify for ANSI flanges: nominal size (NPS), pressure class, face type (RF, FF, RTJ), and schedule/bore.

3. DIN and PN flanges: metric and nominal pressure

DIN EN 1092-1 flanges are dimensioned in millimetres and rated by PN (Nominal Pressure in bar): PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN250, PN400. The higher the PN, the thicker the flange and the smaller/stronger the bolt pattern.

Note that PN is a nominal rating — actual allowable pressure also depends on temperature and material, similar to the ANSI system.

4. JIS flanges: the K rating

Japanese JIS B2220 flanges use the K rating: 5K, 10K, 16K, 20K, 30K. JIS flanges are metric but with their own unique dimensions and bolt patterns. 10K is the most common for general industrial service in Japan and much of Southeast Asia.

5. Rough cross-reference (do not assume interchangeability)

⚠️ These are only approximate pressure equivalences. Bolt circle diameters and bolt hole counts usually differ between systems, so flanges from different standards generally cannot be bolted together.

6. Flange face types you need to know

• Flat Face (FF) — full flat surface, used at low pressure and with cast-iron equipment.
• Raised Face (RF) — the standard for ANSI 150–600 lb; gasket sits on a raised ring.
• Ring Type Joint (RTJ) — metal-to-metal seal for high-pressure, high-temperature service.

7. Tips for buying flanges internationally

1. Always specify the standard first — ANSI, DIN or JIS — before any dimensions.
2. State the pressure rating correctly (Class 150 vs PN16 vs 10K).
3. Confirm the face type (RF, FF, RTJ) and any raised-face height.
4. Specify material (e.g. A105 carbon, 304/316 stainless, or special alloys).
5. Send a drawing or photo of your current flange if you are replacing an existing one.

As a specialist manufacturer of non-standard and large-diameter forged flanges, Feiyu Flange can produce ANSI, DIN, JIS and custom flanges up to very large sizes. Send us your existing flange dimensions and we will match them exactly.

Frequently Asked Questions