What is the difference between a 2-piece and a 3-piece union?

In this set each union has two parts: the nut and the tail piece, plus a flat gasket. Together with the male thread on the unit they form a 3-piece union, so the unit can be removed without twisting the pipe.

Are the gaskets included?

Yes. Each set comes with two flat gaskets, one per union.

What thread does the union have?

G thread (parallel), on both the nut and the tail piece, the same size on both sides.

Do I need hemp or tape?

Not on the nut: it seals on the flat gasket. On the male thread of the tail piece, where your pipe connects, seal as usual for that joint.

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3-piece union in brass and stainless steel

A 3-piece union makes a pipe detachable from a unit with a male thread, such as a heat exchanger, pump or valve. Our unions consist of a nut with female thread, a tail piece with male thread and a flat gasket; the male thread on the unit forms the third part. They come in sets of two, in brass or in stainless steel (AISI 304).

Choose material and size

3-piece union, brass (2 pcs./Set)5 sizes: G3/4", G1", G5/4", G2", G2,5"

3-piece union, stainless steel4 sizes: G3/4", G1", G5/4", G2"

How a 3-piece union works

The nut screws onto the male thread of the unit. The flat gasket sits between the unit and the tail piece and seals the joint; your pipe connects to the male thread of the tail piece. Because the union seals on the gasket and not in the thread, the nut needs no hemp or tape.

When the unit needs replacing or cleaning, you undo the nut and take it out. The pipe does not have to be cut, unsoldered or twisted.

What is in the set

Enough for a flow and a return:

2 nuts with female thread
2 tail pieces with male thread
2 flat gaskets

Sizes and thread

Nut and tail piece both have G thread in the same size. A G1" union therefore fits a unit with a G1" male thread and gives you a G1" male thread again on the pipe side.

Brass: G3/4", G1", G5/4", G2" and G2.5"
Stainless steel: G3/4", G1", G5/4" and G2"

Brass or stainless steel

Brass is the usual choice for most heating and cooling installations. Stainless steel (AISI 304) is more resistant to corrosion; choose it where brass is not wanted.

For our heat exchangers

The unions fit the threaded connections of our brazed plate heat exchangers with a G male thread of the same size. Ordering a heat exchanger? Add the unions to the same order.