INSPECTION PIT ACCESS HATCH Russian patent published in 1999 - IPC

FIELD: construction. SUBSTANCE: inspection pit access hatch has a body with an opening and supporting shoulder on the internal contour, supporting base, stiffening ribs and recesses, cover with a bearing surface and bulges - cantilevers, engageable with the body recesses; the contour of the opening in the body and the corresponding contour of the cover bearing surface are outlined by on oval curve, the relation between whose larger axis and the lower axis is within (1.3-1.5):(0.8-1.2). EFFECT: enhanced safety and convenience in use due to expansion of the opening passage area, enhanced durability and reliability of body and cover. 4 cl, 3 dwg