Ever look in your workshop and see cast iron valves covered in grime, oil, or rust? We're talking cast iron gate valves, check valves, and butterfly valves. Dirty valves can leak or get stuck. So how do you clean them? Let's get into it.
Get your cleaning tools ready. You need a heavy-duty degreaser safe for cast iron. I once used the wrong degreaser and damaged a valve-don't make that mistake! Also, grab a stiff wire brush for rust and a soft one for gentle scrubbing. Have lots of rags and small tools like toothpicks for tight spots, especially in check valves.
Prep the valve before cleaning. Turn off the system and close the valve. If you can, remove it from the line to clean better. If not, cover nearby pipes with plastic. Check the valve for cracks or broken parts. I found a check valve with a bent flap that needed replacing, not just cleaning.
Start by spraying degreaser all over the valve. Focus on oily areas, like where the flap moves in check valves. Let the degreaser sit for 5–10 minutes. Old, baked-on oil might need a second spray.
Each valve type needs different scrubbing. For gate valves, scrub the gate and seat with a soft brush. Use a toothpick to remove debris from the seat-rust here causes leaks. Clean the stem threads with a stiff brush and degreaser, then wipe clean.
For check valves, open the cover and take out the flap. Scrub the flap's rubber seal with a soft brush. Use a pick to remove rust from the seat. A dirty seat makes the valve leak. I fixed a leaky check valve just by cleaning the seat.
Butterfly valves need cleaning on the disc and seal. Open the valve and scrub the disc gently-don't scratch the rubber seal. Wipe the shaft with degreaser and dry it well. A dirty shaft makes the valve hard to turn.
Rinse the valve with low-pressure water. High pressure can force water into bad spots. Dry every part with a rag-cast iron rusts fast. I once left a valve wet and it rusted overnight.
Lubricate the valve after drying. Put grease on the stem of gate valves or the shaft of butterfly valves. Reinstall the valve, making sure check valve flaps face the right way (follow the arrow). Test the valve: butterfly valves should turn easily, check valves should snap shut without leaks.
Here are some tips. If a gate valve handle is hard to turn, clean the stem again and add more grease. For check valves, pour water through them to see if they close. Butterfly valves need a good seal check-cracks mean replacement. Clean valves every 6–12 months to keep them working.