For a 300‑atm hull you need a triple‑layered approach. First, use metal‑to‑metal quick‑release fittings with a built‑in gasket—think a twin O‑ring system backed by a metal washer to take the load. Second, apply a high‑temperature, high‑pressure sealant like a polyurea around the mating surfaces, then cure it under pressure to lock everything in place. Finally, run a burst test on the joint before commissioning and keep a spare gasket kit in the crew quarters. Keep the torque on the bolts precise, use a calibrated torque wrench, and you’ll have a joint that holds like a sealed cave.