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Seating Rings/Adjusting Units
Made to BS EN 1917:2002 and BS 5911-3:2010 concrete frame adjusting/seating rings are reinforced 65mm deep units which can be used in place of engineering bricks to adjust the ductile or cast iron covers and frames to the required level.
They can be quickly and easily installed by semi-skilled labour and there are fewer joints which reduce the likelihood of infiltration.
The advantages of adjusting units are:
- Designed to sit on top of the manhole cover
- Quick and easy to install by semi-skilled labour, reducing costs
- Eliminates laying engineering bricks on-site, reducing reliance on brick availability and cost increases, as well as vertical joint weak 65mm thick – similar to brickwork for consistency and comprehensive strength similar to Class B Engineering bricks
- There are fewer joints which reduce the likelihood of infiltration
- There is a reduced risk of on-site damage and pilferage
Seating/adjusting types
Manhole Seating Rings are manufactured to BS 5911-3 standard in the following sizes…
One-part Seating Rings
600mm x 600mm access
675mm x 675mm access
750mm x 600mm access
750mm x 750mm access
600mm x 600mm eccentric
600mm x 600mm notched
675mm x 675mm notched
750mm x 600mm notched
750mm x 750mm notched
Two-part Seating Rings
600mm x 600mm access
675mm x 675mm access
900mm x 900mm access
1200mm x 675mm access
| Access | Product Drawing | Weight | Pack size | Pack weight |
| One-part | ||||
| 600 x 600mm | 70kg | 15 | 1050kg | |
| 675 x 675mm | 53kg | 15 | 795kg | |
| 750 x 600mm | 66kg | 10 | 660kg | |
| 750 x 750mm | 80kg | 10 | 800kg | |
| 900 x 600mm | 75kg | 12 | 900kg | |
| 600 x 600mm (eccentric) |
80kg | 10 | 800kg | |
| 600 x 600mm (notch) |
63kg | 15 | 945kg | |
| 675 x 675mm (notch) |
58kg | 15 | 870kg | |
| 750 x 600mm (notch) |
78kg | 10 | 780kg | |
| 750 x 750mm (notch) |
75kg | 10 | 750kg | |
| Two-part | ||||
| 600 x 600mm | 48kg | 15 | 720kg | |
| 675 x 675mm | 56kg | 15 | 840kg | |
| 900 x 900mm | 50kg | 10 | 500kg | |
| 1200 x 675mm | 90kg | 10 | 900kg | |
Lothian Seating Slabs
The Scottish Water seating slab or Lothian Seating Slabs (access opening size) is designed to comply with Scottish Water Services Specifications.
It is used in place of engineering bricks to adjust the ductile or cast-iron covers and frames to the required level.
Lothian Seating rings are not affected by moisture, fire or lose their shape in normal groundwater conditions.
Seating Rings/Adjusting Units and Section 38 Agreements
Section 38 (Highways Act 1980) is the term for the legal agreement that allows a highway authority to “adopt” a road (meaning it will be maintained by the highways authority at the public’s expense) which has been constructed by a private developer for 5 or more dwellings.
The developer has to be able to prove that the road has been constructed in accordance with standards set out by the highways authority to enable the highways authority to be able to “adopt” it under a Section 38 legal agreement.
So in the case of concrete frame adjusting/seating rings; units manufactured to BS EN 1917 and BS 5911-3 are shown in both Manual of Contract Documents for Highways Works – Volume 3 – Highway Construction Details – F-Series and in Sewers for Adoption 7th Edition – they are therefore deemed to be accepted for use in highway construction and should not prevent a road from being “adopted” under a Section 38 agreement by a highways authority.
Note: Appearance of a hairline crack in a seating ring or gully cover does not signify failure or a cause for rejection.
Our multi-part adjusting units offer the advantage of light weight sections enabling one man to handle the units and comply with manual handling requirements.
All adjusting units/seating rings
It is the responsibility of the customer to check that the proposed cover and frame flange is fully supported by the chosen adjusting system as flange sizes may vary.
