GB Marine Butterfly Valve Standard Link:

01 GB/T3037 Marine Double-eccentric Center Butterfly Valve

02 GB/T3036 Marine Center Line-type Butterfly Valve

1. It speaks “metric” – so it fits Chinese ships perfectly

GB valves are built around DN (Nominal Diameter) sizes: DN50, DN100, DN300, DN600… These numbers roughly tell you the inner pipe diameter in millimetres. Because Chinese shipyards design everything in the metric system, a DN100 GB valve drops straight into a DN100 pipe without messy adapters.

• Matches the yard’s piping system out of the box

• Lower purchase cost thanks to mass domestic production

• Spare parts and accessories are easy to find in China

If you ever hear someone say “metric-based structure,” this is all they mean.

2. Built for the sea, not for a garden

A boat lives in a harsh world—salt, vibration, cramped spaces. So GB marine butterfly valves are deliberately:

• Compact and lightweight – easy to squeeze into tight engine rooms.

• Corrosion-resistant – materials fight off rust and salt damage.

• Simple to maintain – when you’re at sea, you want repairs that don’t need a PhD.

3. Smart material choices – the “jewellery” of valves

The body (the main case) can be cast iron, ductile iron, cast steel, or stainless steel—depending on how tough the job is.
The disc—the flap that actually blocks the water—is where things get clever.

Common discs: stainless steel, bronze, and a star performer called nickel aluminium bronze.
Think of nickel aluminium bronze like a high-grade marine watch. It doesn’t just resist seawater; it almost ignores it. Excellent corrosion resistance and very long life in salt water make it the premium choice for critical seawater systems.

4. Pressure ratings – what the numbers PN10 and PN16 mean

You’ll see labels like PN10 or PN16. This is simply the pressure the valve is designed to handle under normal conditions.
PN10 = 10 bar (roughly the pressure you’d feel 100 metres underwater).
PN16 = 16 bar.
Most shipboard cooling and ballast systems are perfectly happy with one of these two.

5. Flange connections – the “bolt circles” that can surprise you

A flange is the flat rim with holes that you bolt to the pipe. GB flange drilling (the bolt circle diameter, number of holes, hole size) is very similar to the German DIN standard—especially at the same PN rating. But here’s the catch: even if two valves share the same DN and PN, their face-to-face length (how long the valve is along the pipe) can be different. So you can’t always swap a GB valve directly for a DIN one without checking the actual dimensions.