How to Remove Rusted Cast-Iron Pipe Fittings
- 1). Cut off the water. Before you begin to remove the cast-iron pipe fitting, cut off the water or the steam that flows through the pipe.
- 2). Lubricate the pipe fitting. Apply an oil-based lubricant to the pipe fitting and the connecting pipe. This helps to soften the rust. Use mineral oil for a lubricant. Apply this with a paper towel. According to the article "Rusted Pipes" on the Mr. Hardware website, products like WD-40, Liquid Wrench and PB Blaster also work well. Spray on one of these three products. Mr. Hardware says to "wait a minute or two and your pipe should break free." Hardware stores sell these products
- 3). Hit the fitting. If the pipe fitting is stubborn there are a few things you can do. The Mr. Hardware site suggests "hitting the fitting a time or two." This loosens up the rust encasing the fitting. Use a hammer or a wrench for hitting the cast iron pipe fitting.
- 4). Loosen and remove the pipe fitting. To remove the pipe fitting use a wrench. According to the article "Pipe Replacement" on the On the House website, 'Using two medium pipe wrenches in opposing directions (one gripping the pipe and the other the fitting) will provide the leverage needed to break the connection." If the fitting is still too difficult to remove, add more lubricant and wait 15 minutes. Then use the two pipe wrenches again.
Source...