ANSI Marine Butterfly Valve Manufacturer

ANSI Marine Butterfly Valve

Pressure Rating	Class 150/300/600 with pressure‑temperature curve. Not fixed PSI. Differs from PN/K systems.
Flange Standard	ASME B16.5 / B16.47 inch flanges. Not interchangeable with DN; main cause of fit‑up issues.
Structural Features	High‑capacity disc. Seats: EPDM, NBR, PTFE, metal. Often fire‑safe & seawater‑resistant.

Overview

ANSI Marine Butterfly Valve Standard Link:

01 API Triple Eccentric Butterfly Valve | 150LB-900LB Metal Seated Valve Manufacturer

02 Class 300 LB API Flange Butterfly Valve | High-Pressure Industrial Valve Supplier

03 Class 150 LB API Flange Butterfly Valve | Industrial Valve Manufacturer & Supplier

1. The Most Distinctive Feature: Class Rating, Not PN
ANSI marine butterfly valves use a Class Rating system (e.g., Class 150, Class 300, Class 600).
This does not mean the valve is rated for 150 PSI working pressure. Instead, it follows a pressure-temperature rating system – the allowable pressure depends on both the class and the operating temperature.

By contrast, GB, DIN, and JIS standards normally use fixed nominal pressure designations such as PN10, PN16, PN25, or PN40.

Standard	Typical pressure designation
ANSI	Class 150 / 300 / 600
DIN	PN10 / PN16
GB	PN10 / PN16
JIS	5K / 10K / 16K

In short, an ANSI valve belongs to the inch-based imperial engineering system, which is fundamentally different from the metric-based PN system.

2. Flange Dimension Differences – The Most Critical Factor
Roughly 90% of installation problems with marine butterfly valves come from flange mismatch.

ANSI valves use flanges conforming to ASME B16.5 or B16.47, characterized by:

Inch nominal diameters
ASME-defined flange dimensions
Imperial bolt circles

For example, an ANSI 6" valve nominally corresponds to DN150, but DN150 is not automatically interchangeable with ANSI 6".
The differences lie in:

Flange outside diameter (OD)
Bolt circle diameter
Number and size of bolt holes

Key takeaway: An ANSI butterfly valve cannot simply replace a DIN valve without verifying flange compatibility.

Where ANSI Valves Are Commonly Used
ANSI marine butterfly valves are widely adopted where the following apply:

International oil & gas projects
Offshore platforms
Shipyards in the US and Europe
Compatibility with API/ASME piping systems
Interfaces with American-made equipment

Their advantages include a larger pressure margin, strong compatibility with API and ASME systems, and easy integration with US-standard equipment.

6. Are There Structural Differences in ANSI Marine Butterfly Valves?

Yes. Two areas stand out:

① Disc Design
ANSI‑market valves are often engineered for higher flow capacity and stronger pressure capability, reflecting the performance expectations of ASME/API applications.

② Seat Material Selection
In marine environments, common seat materials are: