Black Unions
A black union is a malleable cast iron fitting with one female-threaded end and one nut-connected end that connects equipment detachably on a black steel pipeline. When the nut is opened, both sides separate without turning the pipe.
It is used for maintenance and replacement at boiler, calorifier, radiator and meter connections. The store stocks 1″, 1 1/4″, 1 1/2″ and 2″ sizes with a black surface suitable for central heating and indoor gas lines.
Main Applications
- Boiler flow and return connections
- Calorifier and heat exchanger separation
- Maintenance points at riser and manifold connections
- Upstream of meters and regulators (in projects compliant with regulations)
- Pump and circulation group connections
- Compressor and tank connections
Technical Data
| Fitting type | Union with nut |
|---|---|
| Product standard | TS EN 10242, design symbol A (manufacturer information) |
| Material | Blackheart malleable cast iron B 350-10 (sales sheet information) |
| Surface | Black, without galvanized coating |
| Thread | ISO 7-1 Rp female / R male thread (depending on model) |
| Sizes | 1″, 1 1/4″, 1 1/2″, 2″ (product range) |
| Seat | Taper metal or flat face, depending on model |
| Permissible pressure | 25 bar, −20 … +120 °C (EN 10242, design A) |
| Pressure at high temperature | 20 bar, up to +300 °C (EN 10242, design A) |
| Leak test | At least 5 bar air or 20 bar water (sales sheet information) |
| Nut | Hexagonal, malleable cast iron |
| Wider size range | 1/2″ – 4″ with black taper seat unions |
Material Options
| Part | Black malleable iron | Galvanized malleable iron | Stainless steel casting |
|---|---|---|---|
| Body | Blackheart malleable cast iron B 350-10 | Malleable iron EN-GJMB-350-10, hot-dip galvanized | Investment casting, depending on model |
| Nut | Blackheart malleable cast iron B 350-10 | Malleable iron, galvanized | Stainless casting, depending on model |
| Seat | Depending on model | Depending on model | Depending on model |
| Surface | Black, uncoated | Zinc coated | Stainless, uncoated |
| Pressure rating | 25 bar −20…120 °C, 20 bar 300 °C (EN 10242) | 25 bar −20…120 °C (EN 10242) | Depending on model |
Which material? A black union keeps the same surface as the pipe and other fittings in heating and gas lines; a galvanized union should be used in fresh water lines.
Advantages
Easy Equipment Replacement
- The pipework stays in place while the boiler or meter is removed
Connection Without Turning Pipe
- Joined by tightening the nut; pipes are not rotated
Heat Resistance
- Rated 20 bar at +300 °C, suitable for boiler rooms
Compact Design
- Its short length fits tight connection points
Construction and Design Features
- Female-threaded body on one end and a mating part joined by a nut on the other
- Hexagonal nut and body for easy holding with a wrench
- Seat type depending on model (taper metal or flat)
- TS EN 10242 design A
Send the union size and quantity; we will prepare black fittings suitable for the boiler or meter connection together.
How to Choose?
- Identify the equipmentMeasure the connection size of the boiler, calorifier, meter or pump to be removable.
- Check the sizeChoose a union for 1″ – 2″ and a taper seat union for smaller or larger sizes.
- Match the end typesPlan the female-threaded end of the body towards the pipe and the nut end towards the equipment.
- Verify pressure and temperatureCompare the highest pressure and temperature of the boiler or meter line with 25 bar/120 °C and 20 bar/300 °C.
Complementary Products
Why ORFA?
Other Threaded Black Fittings
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Threaded black tees are equal-size fittings used to split flow in three directions on threaded black steel pipelines.
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Black Pipe Crossover Bends
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Black Elbows
Black elbows are fittings used to change direction by 90 degrees on threaded black steel pipelines.
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Black Reducing Tees
Black reducing tees are fittings used to take a smaller branch off the main run on threaded black steel lines.
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Black Conical Unions
Black conical unions provide a tight, removable connection on threaded black steel pipes through a conical seat.
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Black Plugs and Caps
Black plugs and caps are used to close the ends of threaded black steel pipes and fittings.
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Black Crosses
Black crosses are fittings that split flow in four directions on threaded black steel pipelines.
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Black Street Elbows
Black street elbows have one female and one male threaded end and change direction on black steel lines without an extra nipple.
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Black Reducing Sockets
Black reducing sockets are female threaded fittings that join two black steel pipes of different sizes.
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Black Sockets
Black sockets are female threaded fittings that join two black steel pipes of the same size in a straight line.
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Black Nipples
Black nipples are short black steel pieces with male threads on both ends, used to connect two female threaded fittings.
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Black Reducing Bushes
Black reducing bushes are fittings with male and female threads used to change pipe size on threaded black steel lines.
Details →Get a quote for your project
Our sales team will prepare the best solution for your needs.