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Cast bronze solder union, 1-1/4 inch, satin metallic finish

Nibco, Inc.

Nibco, Inc. 733-4 Cast Bronze Solder Pressure Copper Union 1-1/4 In

SKU CH-2R7P-B0Z2T

Cast bronze solder union joins 1-1/4 inch copper pipe, rated 351 psi at 200 °F with a -20 to 400 °F range per ASME B16.18

  • Cast bronze construction resists corrosion in plumbing systems
  • Solder joint with male NPT threads ensures secure leak-free connections
  • Rated to 351 psi at 200 degrees F for high-pressure applications
  • Operates from -20 to 400 degrees F across wide temperature ranges
  • Meets ASME B16.18 standard for reliable fitting performance

Cast Bronze Solder Union

The Nibco 733-4 is a 1-1/4 inch cast bronze solder pressure copper union designed for joining copper tubing in plumbing and heating systems. It features a C x MNPT connection type with an outside diameter of 1-3/8 inches by 1-1/4 inches. The fitting meets ASME B16.18 standards for quality and dimensional consistency.

Suited for high-temperature hydronic lines

This union handles a temperature range from -20 degrees to 400 degrees Fahrenheit, making it appropriate for hot water heating and steam applications up to the rated limit. It is not intended for systems exceeding 351 psi at 200 degrees Fahrenheit or for press-fit and push-to-connect installation methods.

Pressure headroom for residential hydronics

At the 200 degrees Fahrenheit reference point the fitting holds 351 psi, giving ample margin for typical closed-loop heating pressures. Capacity drops as temperatures climb toward the 400 degrees Fahrenheit maximum, so designers must verify the pressure-temperature curve for their specific operating conditions.

How it compares

Measured against everything we stock in Hose Fittings, Adapters & Clamps, at today’s prices. Recalculated every night.

Price $62.99
Pricier than about 84% of the 2,955 comparable items (median $17.99).

Specifications

Product
Brand nameNibco

Questions about this item

What copper tube size must I already have to solder this 1-1/4 In. union?

You need 1-1/4 In. copper tube; the union's solder end is sized for that exact outside diameter.

Will the male NPT threads on this union mate with my existing 1-1/4 In. threaded pipe or valve?

Yes, the C x MNPT configuration provides 1-1/4 In. male NPT threads that match standard 1-1/4 In. female threaded fittings.

How can I verify the joint is holding at the rated 351 psi@200 Degrees F after I solder and thread it?

Pressurise the system to working pressure and inspect the soldered cup and threaded connection for leaks; the union meets ASME B16.18 for that pressure-temperature rating.

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