Precast Manhole system IS 17725 /2022

PRECAST MANHOLE SYSTEM

Precast Manhole System is a replacement to existing cast at site & brick masonry construction, it has it’s own advantages. A typical Manhole System includes the following components.

  • Base Section

  • Riser Section

  • Cone Eccentric Section

  • Adjusting Ring

  • Cover & Frame

  • Transition Slab

BASE SECTION

The Base Section is manufactured monolithically with base slab (flush/projected) along the Base Section has several functions, such as:

  • To establish a solid foundation for the whole precast Manhole system and the connecting pipes and carry load of an eventual traffic.

  • To connect two or more adjoining pipes preferably with flexible joints, having the same specifications as the joints in the adjoining and cleaning.

  • To provide easy access to the pipelines for inspection and cleaning

  • To divert the main pipeline direction if required.

RISER SECTION

The function of riser unit is to provide a safe access connection from ground level to the pipeline. Riser section consists of a cylindrical section with an effective depth of 300mm to 1500mm. The provision for house service connection in the riser section of the manhole may be provided and if provided then dummy hole deep impression having minimum thickness of wall 50mm at that location for facilitating house service connection shall be provided.

CONE SECTION

Cone section is commonly installed on the riser section. The function of the cone section is to reduce the diameter of the top cover and still provide an opening large enough for a person to enter into the precast manhole system. Also the cone section has the function of distributing an eventual traffic load to the riser sections and further down to the base section. By using eccentric cones a straight vertical access is provided for the persons entering the precast manhole system. Cone Section may be manufactured with or without manhole frame Arrangement. The top opening of the cone section is Ø 560mm. However essentially tongue and groove joint/ internal flush joint between cone and frame shall be provided to take care of shear loads.

 

ADJUSTING RING

The function of the adjusting unit is to bring the top level of the precast manhole system to match the road top or level/any other specified level with any type of joint matching with its bottom and top components.

COVER & FRAME

The function of the cover and frame is to close the access to the manhole. The cover and frame used for circular precast concrete manhole shall as per IS 12592.

TRANSITION SLABS

Transition slab is component that serves to connect base section of the manhole to access shaft of diameter 1200mm. the type of joint shall be matched with it’s bottom and top components.

JOINTS

Manhole components can be jointed together with different types of joints

  1. Internal Flush Joint.

  2. Tongue/grooved Joint The main function of Joints is to prevent the Manhole components to dislocate from their ideal positions. To obtain a degree of fitness for this type of joints it is common to use mastic rubber and cement mortar as the sealing element.

DESCRIPTION
HEIGHT
INLET & OUTLET DIA
REMARK
1200MM MANHOLE BASE
650mm
100mm to 250mm
RCC, HDPE, DWC
1200MM MANHOLE BASE
1000mm
300mm to 600mm
ECCENTRIC CONE
900mm
RISER
900mm , 600mm , 300mm
ADJUSTING RING
100mm,75mm,50mm
COVER
100mm
1500MM MANHOLE BASE
1200mm
350mm to 450mm
RCC & HDPE PIPE, DWC
1500MM MANHOLE BASE
1400mm
450mm to 900mm
RCC & HDPE PIPE, DWC
TRANSITION SLAB
200mm
Required with every 1500m Manhole

Ø 1200MM PRECAST MANHOLE BASE DEPTH 650MM

WP Data Tables

Ø 1200MM PRECAST MANHOLE BASE DEPTH 1000MM

WP Data Tables

Ø 1500MM PRECAST MANHOLE BASE DEPTH 1200MM

WP Data Tables

Ø 1500MM PRECAST MANHOLE BASE DEPTH 1400MM

WP Data Tables

Medhavi Prestressed Pipes Pvt. Ltd., a key unit of the Medhavi Group, is headquartered at MIDC, Nanded, Maharashtra.

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