How waterproof are acrylic welds?


hi-- i am making a waterproof housing using techniques similar to (inspired by) the openrov design. i was wondering if any of you have any intuition as to how waterproof the acrylic weld joints are? for reference: i am intending to make an endcap out of layers of acrylic bonded together. part of the endcap will be a sandwich, where an air cavity is completely enclosed by acrylic—think of three layers: a disk, a ring, another disk; the air cavity is created by sandwiching the ring between two disks. i am thinking that at high pressure there will be some risk of acrylic delamination or of water leaking into the cavity. does anyone know how robust this construction is likely to be? thanks!