How to open a gate valve with a detached disc
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If the gate valve disc falls off but the handwheel can still be turned, the disc can be pushed back onto the seat to reopen the valve by operating the handwheel. If this is not possible, professional repair or a new valve is required. The specific steps are as follows:

**Steps to reopen the valve after the disc has fallen off:**
1. **Check the handwheel’s condition:** If the handwheel turns, it means the valve stem is not completely damaged. Turn the handwheel slowly in the closing direction to try to push the disc back onto the seat and establish a seal.
2. Ensure that the medium pressure is balanced before proceeding (if there is a bypass valve, open it first).
3. **Loosen the valve cover assembly:** Unscrew the gland nuts to release the pressure on the packing. Loosen the valve cover bolts gradually to prevent the valve cover from separating suddenly.
4. **Separate the valve cover to expose the disc:** Keep turning the handwheel until the valve stem cannot move anymore. At this point, the part of the valve cover above the disc will separate from the valve body. Once it is confirmed that the disc is sealed with the seat, completely remove the bolts and take off the valve cover, valve stem, and other components to expose the top of the disc.
5. **Repair the connection and test:** If the connection between the valve stem and the disc is damaged, repair it using welding or a high-strength adhesive (welding is not allowed for flammable media). After reassembling, turn the handwheel to test whether the valve opens smoothly and ensure there is no leakage.
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