Brass ball valves are fine until they aren't. Coastal sites, pool plant, bore water, buried services and chemical wash-down areas all chew through brass. Then you're back replacing valves that should have lasted 20 years.
316 stainless fixes the corrosion. The trouble is that on potable water it still has to be WaterMarked, and the stainless range on offer has historically been thin.
Zetco's new range covers it properly: 2-piece and 3-piece, lever and T handle, M&F, underground and socket weld, all listed as WaterMarked. Here's how to pick.
AS 5830.1 vs AS 4796: What the Label Means
You'll see two certification standards across this range.
- AS 5830.1: the PN40 2-piece valves carry this one (licence WM-022438 per Zetco), and they're rated to 4000 kPa.
- AS 4796: the full-316 valves carry this one (licence WM-022701 per Zetco), and they're rated to 2500 kPa.
For a plumber the practical point is simple. Both are WaterMark listings for potable water, and the difference that matters on the job is the pressure rating on the label. Check it against your system, and if a spec calls up a particular standard, match it.
Some valves carry a general WaterMark listing (WM-022793), including the 3-piece lockable and socket weld valves below.
2-Piece: The Everyday Stainless Valve
A 2-piece body is two parts screwed together around the ball. It's compact and cost-effective, but if a seat fails, the whole valve comes out.
- Series 4402: M&F BSP, lever handle, 6–50mm, PN40. The male end screws straight into a fitting, so you skip a nipple.
- Series 4401: F&F BSP, T handle, 6–32mm. Use it behind access panels, in cabinets and anywhere a lever can't swing.
- Series 4403: M&F with a T handle, for equipment connections in tight spots.
- Series 4494: F&F with a lockable 316 handle, 10–50mm, AS 4796. On coastal and pool jobs, a plated or 304 handle is the first thing to rust.
3-Piece: When You'll Be Back to Service It
A 3-piece valve has a centre body held between two end caps by bolts. Undo the bolts, swing the centre out, and you can replace seats and seals without cutting the line.
That's why 3-piece valves get specified on commercial plant, hot water plant rooms and process lines.
- Series 4419: F&F BSP, lockable lever, 6–100mm, 4000 kPa. This is the workhorse, and it's the only threaded one here that goes to 100mm.
- Series 4429: every part in 316, handle included, 15–50mm, AS 4796. For marine, coastal and chemical environments.
- Series 4422: socket weld ends for welded stainless systems, rated -60°C to 150°C. Swinging the centre out also keeps the seats away from welding heat, which is the main reason for choosing 3-piece on welded lines.
Underground: Key-Operated From the Surface
The series 4405 underground ball valve has a square cap instead of a lever, for key operation from the surface through a valve box.
It's listed as WaterMarked to both AS 5830.1 and AS 4796 and runs 25–50mm. Zetco rates it at 4000 kPa, or 2500 kPa under AS 4796.
Use it on buried services in aggressive or reactive soils where brass would dezincify.
Choosing a Handle
- Lever: fastest to operate, and the position is obvious at a glance. Needs swing room.
- T handle: compact, for panels, cabinets and tight risers.
- Lockable lever: for anything covered by lock-out procedures, or isolating a building, plant or public area.
- Square cap: for buried valves operated with a key.
A Note on Ratings
Zetco lists these valves at -20°C to 150°C, or 120°C for 4494 and 4405. That covers hot water plant comfortably.
Don't confuse them with the non-WaterMarked stainless valves in the same range, like the spring return, self-venting and high-pressure valves. Those are for process and industrial lines, not AS/NZS 3500 work. We cover them in our special-duty ball valve guide.
The Short Version
Use 2-piece for everyday stainless isolation and 3-piece wherever you'll want to service in place. Go full 316 for marine and chemical sites, and square cap for buried services. Then check the WaterMark listing and pressure rating on the label match the job.
Browse the range in our ball valves and Zetco collections. For coastal fit-offs, see 316 outdoor tapware for coastal installs.
Frequently Asked Questions
Are Zetco stainless ball valves WaterMarked?
The valves in this post are listed by Zetco as WaterMarked, to AS 5830.1, AS 4796 or both depending on the series. Check the licence and pressure rating on the specific valve against your job.
What's the advantage of a 3-piece ball valve?
The centre section swings out, so you can replace seats and seals without cutting the valve out. That makes it the better choice on plant rooms, process lines and welded systems.
When should I use a T handle instead of a lever?
Where a lever can't swing freely: behind access panels, inside cabinets and in tight risers.
Why use a stainless underground valve instead of brass?
Aggressive soils can dezincify brass. A 316 stainless body resists that, and the square cap lets you operate it with a key from the surface.