Manhole manufacturers launch a large number of new products

Manholes are openings designed for personnel access to equipment for installation, maintenance, and safety inspections. They are primarily composed of short筒节 (or short pipes), flanges, and handles on the manhole covers. For safety inspection considerations, pressure vessels are required to have a specific number of manholes and their small sizes are referred to as "inspection holes." Manhole materials include carbon steel and stainless steel. Manholes are categorized by pressure conditions into atmospheric and pressure manholes; by shape into round, elliptical, and rectangular manholes, with rectangular manholes suitable only for atmospheric pressure 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-opening. Manhole structures and dimensions are generally standardized and can be selected or designed according to relevant manuals.