Will ground glass joints relieve pressure non-catastrophically? I need to heat a fluid for seven days at a time. The fluid goes in round bottom flask that is suspended in a water bath. The test fluid will decompose and generate a small amount of gas over time.

Gas generation is variable and dependent on what material I am testing in this material compatibility experiment.

I have experience in plumbing and fluid systems but not chemistry. In a plumbing system I would add a relief valve to relieve the pressure generated over time, without allowing potentially dirty air to contaminate the experiment.

I have a ground glass joint. I found a source that says the ground glass plug will lift to relieve pressure, even if I put a plastic clip on it, and the plastic clip would ensure the plug would not go flying.

I still have concern since this is an environment I am not familiar with, and I am not keen on exploding glassware in the facility. Past experimenters have placed small beakers upside down on top of the flask, and have also used aluminum foil as a cover (I will not do this so the vapor contact with foil does not affect the experiment results). I tried it with a beaker but a moderate amount of fluid condensed on the surface, which was not ideal.

Will I be fine securing a ground glass joint with a plastic clip, should I use an upside down beaker, or is there a more obvious solution?
Ground-glass joints are notorious for seizing at the wrong time, particularly if reactants are alkaline.

If pressure might change, I'd add some relief mechanism, such as a water-trap or rupture disk. Without knowing your setup, something as simple as a balloon might work, if not attacked by reactants.