How to Break Cast Iron Pipe Unions

Tap around the union's radial nut with a hammer.

Cast iron union joints are installed into steel gas lines or other types of metal pipelines, and are usually fitted at periodic intervals. The union's purpose is to allow for a section of the pipeline to be removed on each side of it, without taking apart all the line from the pipe's end to that point. Each union joint has male and female end nuts, with a central radial nut attached to the female nut. The female nut is usually loosened with a pipe wrench. But if rusted in place, extra force is necessary to remove it.

Things You'll Need

• Pipe wrench
• Hammer

Instructions

1. Turn off the gas or water supply to the pipeline. Locate the cast iron union in the pipe, and place its central radial nut in the jaws of a pipe wrench.

2. Turn the wrench handle counterclockwise to attempt to loosen the nut. If the nut has rusted and refuses to budge, tap lightly around the radial nut with a hammer. Cast iron, though strong, is also quite brittle and will break if it receives a sizable knock. Continue tapping around it, increasing the force of the hammer blows until the nut fractures and breaks.

3. Remove the broken radial nut. Place the pipe wrench on each of the end nuts, turning the wrench counterclockwise. When the nuts become loose, unthread them from the pipe ends by hand.

Tips & Warnings

• If it is desired only to damage the union as a last resort, apply lubricating spray around the radial nut's threads, wait 15 minutes and attempt to loosen the nut again with the wrench. Repeat this several times before resorting to the hammer.

References

• Pipe Fittings And Flanges: Pipe Union
• "Home Improvement 1-2-3"; Christopher Cavanaugh; 1995