How to Remove a Rounded Hex Nut From a Propane Tank

Common propane tank connected to a gas grill.

A hex nut, short for hexagonal or six-sided, twists onto a threaded connection to hold two parts together. The sides of the hex nut can wear down and become rounded from repeated twisting or if an incorrect wrench size is used to loosen the nut. As the wrench slips, it wears down the edges until you can no longer get a grip on the nut. Remove a rounded hex nut on a propane tank, whether at the hose coupler or when mounting hardware to a bracket, with a lock-type pliers.

Things You'll Need

• Spray lubricant
• Locking pliers

Instructions

1. Shut off the gas by twisting the knob on top of the propane tank completely clockwise.

2. Spray the rounded hex nut with lubricant and allow the lubricant to work for half an hour.

3. Turn the threaded knob on the handle of the locking pliers or vise grips clockwise while holding the jaws as tight as possible on the rounded nut. Take off the pliers.

4. Twist the threaded knob on the locking pliers another quarter turn clockwise with the jaws open, then place the jaws on the rounded hex nut and squeeze the handles until the pliers lock.

5. Turn the plier handles counterclockwise to loosen and slowly remove the rounded nut.

Tips & Warnings

• If the nut still will not come off after using lubricant and locking pliers, contact a gas specialist. More aggressive techniques such as sawing off the bolt should not be attempted due to the danger of rupturing a propane tank under pressure if the power tools slips.

References

• The Family Handyman: How to Loosen Nuts, Bolts and Screws
• Propane 101: What Propane Gas Users Need to Know