Manhole manufacturer

A manhole refers to an opening structure used for personnel entry and exit to facilitate installation, maintenance, and safety inspections. It is mainly composed of short筒节 (or short tube), flanges, and a manhole cover with a handle. In consideration of safety inspections, pressure vessels require a specified number of manholes and their small sizes are listed under "inspection holes." Manhole materials include carbon steel and stainless steel. Manholes are categorized by pressure conditions into atmospheric and pressurized manholes; by shape into circular, elliptical, and rectangular manholes, with rectangular manholes suitable only for atmospheric equipment; by installation position into horizontal and vertical installations; and by cover fixing methods into swivel covers and hinged covers. The opening speed of manholes can be ordinary or quick-open. Manhole structures and dimensions are generally standardized, allowing selection or design according to relevant manuals.