Figure 600 Hammer Union — Bronze Seated, Threaded, 6,000 psi

The Figure 600 is a bronze-seated union built for steam service and for lines where rust, corrosion and condensation attack a metal-to-metal seal.

Applications

Steam service; production and service systems where boiler water or steam seat corrosion is a problem.

Construction and sealing

• Bronze seat insert, which puts a hardness difference across the seats and helps them seal.
• Designed for lines where a metal-to-metal seal is wanted but condensation is a problem.
• Threaded ends.
• Sealing: Metal-to-metal, on a bronze seat insert.
• Seat: Bronze insert.

Working pressure

6,000 psi (414 bar) cold working pressure, tested at 9,000 psi.

How a hammer union makes up

A hammer union is a three-piece connection. A male sub and a female sub carry the two line ends, and a wing nut turns on a thread cut into the male sub and pulls a shoulder on the female sub down onto the seat. The lugs standing proud of the nut are struck with a hammer to tighten it, which is where the name comes from — the joint is made up and broken out with a sledgehammer rather than a wrench, so a line can be rigged and stripped quickly in the field. The seal is made by the seat, not by the thread: the nut only supplies the load that holds the two seating faces together. That is why a union will leak from a scored seat or a perished seal long before the thread is at fault, and why a worn union is usually a sub or a seal replacement rather than a scrap part.

Specifying one

Four things fix a hammer union: the figure number, which sets the pressure class and decides what it will mate with; the service class, standard or sour gas; the end connection, threaded or butt weld; and the nominal size. Figure numbers are an industry series, so a union of the same figure and size from another maker will mate — but the pressure rating stamped on the union is what governs, not the figure number on its own. Send us the line specification and we will confirm the match before quoting.

Sizes and part numbers

Published in 1" to 4" with line pipe threaded ends. Every orderable size, its weight, its dimensions and its working pressure are in the size table on this page. Where dimensions and weight are critical, ask us to confirm them against the build before you order.