Figure 400 Hammer Union — 4,000 psi, Reduced Above 4 in

The Figure 400 is a heavy ball-and-cone union for manifold connections, suction lines and mud systems.

Applications

Manifold connections, suction lines and mud systems.

Construction and sealing

• Ball and cone sealing, which makes the union easy to align and dependable to seal.
• Heavy steel forgings.
• Sealing: Metal-to-metal ball and cone seat.
• Material: Steel forgings.

Working pressure

Rated 4,000 psi (276 bar) cold working pressure at 2 in, 3 in and 4 in, tested at 6,000 psi. The 5 in, 6 in, 10 in and 12 in sizes are reduced to 2,500 psi (172 bar), tested at 3,750 psi.

The 5 in, 6 in, 10 in and 12 in sizes are NOT rated at 4,000 psi. They are reduced to 2,500 psi (172 bar) cold working pressure. The size table below states the rating for every size — read it before you specify a large Figure 400.

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 2" to 12" with threaded ends. The size table on this page states the working pressure for every size. Our source publishes no dimension table for this figure, so none is shown — ask us for a dimensioned drawing and we will get it from the mill rather than infer it.