Nibco, Inc. C603 1-1/4" C x FNPT Copper Adapter

Copper Adapter for 1-1/4 Inch Tubing

This Nibco C603 adapter connects 1-1/4 inch copper tube to a 1-1/4 inch female NPT thread. It is made from wrot copper and meets ASME/ANSI B 16.22 standards. The fitting handles pressures up to 439 psi at 100 degrees Fahrenheit. It suits plumbing repairs and new installations requiring a sweat-to-thread transition.

For Sweat-to-Thread Joints in Copper Systems

Plumbers joining copper tubing to threaded pipe or valves will find this adapter matches the required nominal size. The temperature range spans -20 to 400 degrees Fahrenheit for hot and cold water lines. It is not for buyers who need a press-fit or push-to-connect solution without soldering. It also does not suit applications requiring a different nominal diameter or thread standard.

Solder Installation with Standard Tools

Installation requires cleaning, fluxing and sweating the copper end with a torch while the threaded end connects by hand or wrench. The most common issue is overheating the joint, which can damage the threads or cause leaks. Ensure the pipe is fully inserted before heating and allow the joint to cool naturally without disturbance. Proper preparation prevents callbacks.