ANSI 150 SS316 swing check valve, 1/2" to 4"

A swing check valve in 1/2" to 4" (DN15 to DN100), with ANSI 150# flange ends and a body in SS316 with A351 CF8M cast stainless. The gasket is PTFE. Rated Class 150 for service at not published.

It is a disc on a hinge. Forward flow pushes it open and holds it clear of the bore; when flow stops or reverses, the disc swings shut under its own weight and the backpressure behind it. Nothing operates it — no handle, no stem, no actuator — which makes it the cheapest way to stop a stopped pump being spun backwards, and the least visible when it stops working. How it works, in full.

• Face‑to‑face is quoted as the catalogue prints it: 152 mm at 1/2", 178 mm at 3/4", then 127 to 292 mm from 1" to 4", in line with ASME B16.10. On a tight replacement, measure the gap in your run and we confirm the length against a stocked unit.
• No working temperature is published for this variant. The gasket is PTFE. If temperature matters to your duty, ask and we will get the figure from the factory.
• The second size column is the bore in millimetres — 15 to 100 across the range — and the table heads it Bore (mm) alongside the nominal inch size.
• The air test is published as 0.4 to 0.7 MPa, a range rather than a single figure.
• Stainless right through, including the fasteners. Body, disc, arm, hinge pin, bolts and nuts are all SS316 or CF8M. That is worth stating because the threaded stainless variant uses SS304 for its pin, washer and bolt.
• Item 7 of the parts list is printed “S316” in the catalogue — the material is SS316, the same as the rest of the trim.
• It seals 316 on 316, with no hardfacing. The cast steel variant has a separate 13% chrome faced seat; this one does not. On abrasive or frequently cycling duty that difference tells — and a Y‑strainer upstream matters more here than anywhere.
• ⚠ Fit a Y‑strainer upstream. A flake of scale between disc and seat holds the disc fractionally open, and the valve then passes reverse flow while looking perfectly normal from outside. There is no stem position or indicator to check. A strainer is the single most effective thing you can do for a check valve.
• Orientation is not optional. Flow follows the arrow cast into the body; on a horizontal run the bonnet points up; on a vertical run flow must be upward. Never on downward flow — use a spring check for that. The three rules.

Four angles on the same valve. Photographs of the stocked item, not renders.

The manufacturer’s sectional drawing. The callout numbers correspond to the item numbers in the parts list.

• The disc and the seat face are what wear. Everything else is a casting or a fastener. On a valve that closes every time the pump stops, those two surfaces take the whole duty cycle.
• The hinge pin is the other one to ask about. A disc that chatters — which happens when the valve is oversized for the flow — wears the pin, and a worn pin lets the disc sit crooked on the seat.
• The item numbers are the manufacturer’s, matching the callouts on the drawing above, so a spares order matches the section.
• Everything here is published, not on request. If you need to know what touches your fluid, the whole list is above.

• ⚠ Do not design to these figures. The shell test is roughly twice the nominal rating and exists to prove the casting. The valve is not intended to operate there.
• ⚠ What actually breaks a check valve is not pressure. It is slam on flow reversal and chatter at low flow — both of which happen far below the shell rating. Why a swing disc slams, and when to use something else.
• The published figures across the five variants do not line up. Three of them publish no working temperature at all, one publishes no test table at all, and the two flanged stainless variants give the air test as a range where everything else gives a single figure. All five side by side, with every one flagged.