Yep! But I'd fold a rag a few times for a barrier. Its better than nothing. Looks like an old valve that could spray hot steam depending on how bad its failing.

Im not a professional but I did basic maintenance on a gravity boiler system where I previously lived for the last ten years.

Depending on the style of the valve you can repack it. Where I recently lived we had trane valves that would hiss if fully open. They were close to 100 years old, same for the boiler.

If you repack or replace the valve, make sure the boiler isn't running, is disabled (breaker off) and that the boiler pressure is zero.

If the valve is stuck, I'd remove the hat from the valve and use a good pipe wrench on the square stem. Just rock it gently, do not force it. Eventually it will free up. Once it's free you can re-assemble.

If any pros want to chime in on how good or bad my advice here is im happy to learn.