In Australia, manhole also commonly refers to an access hatch used to get access from a room or hallway into the ceiling cavity of a building.[3][4] These manholes are typically around 450 mm × 450 mm (18 in × 18 in) square.
Furthermore, the SRDJ design minimizes the risk of material fatigue. Traditional joints can experience wear and tear over time due to repeated assembly and disassembly. However, because the SRDJ is designed to maintain its integrity without the need for frequent re-tightening or replacement components, it can lead to longer service life and reduced maintenance costs over the system’s lifecycle.
self restrained dismantling joint

Conclusion