Specifier’s guide to precast concrete seating rings (adjusting rings) and gully risers (gully cover slabs)

Products: Precast concrete seating rings and gully risers are a practical and economical alternative to engineering brick coursing, and provide both height adjustment and a robust seating for the ironwork cover and frame assembly. Benefits: (a) Proven durability The durability of precast concrete in drainage applications has been proven through more than 50 years of service in highways across Europe and the United Kingdom. Durability is further assured through manufacture under factory conditions and to specifications which include: •a specified minimum characteristic compressive strength of 40N/mm2 for the concrete •a specified maximum w:c ratio of 0.45 for the concrete •a specified maximum water absorption for the concrete •a specified minimum cover to any reinforcement or handling steel (b) Ease of installation All of these units have been designed to facilitate quick and easy installation on site: •all units are provided with handling recesses •installation on a sand/cement bed can be undertaken by semi-skilled operatives •manhole seating rings have a profiled face to resist lateral movement when installed •two-part adjusting units are available offering the advantages of lighter weight and even greater ease of installation with fewer joints to make the risk of infiltration is minimised Specifications: Manhole cover slab seating rings (adjusting units) are manufactured to: BS EN 1917 and BS 5911-3:2010+A1:2014 Gully risers (cover slabs) are manufactured to: BS 5911-6:2004+A1:2010 The Kitemark: The Kitemark is a quality mark owned and operated by the British Standards institution, and Kitemark licensees are regularly audited by BSI to ensure standards are maintained Having the Kitemark on a product is your third party warrant that it conforms to the stated specification CE marking: CE Marking on a product is a manufacturer’s declaration that it complies with the essential requirements of the relevant Harmonized Standard and is mandated under the Construction Products Directive wherever such Harmonised standard is available All cover slab seating rings are CE marked as conforming to BS EN 1917, and a declaration of performance is available on request Whilst there is no Harmonised Standard for gully risers they are manufactured under exactly the same approved Factory Production Control System Remember: Always specify: Precast concrete seating rings to BS EN1917, BS 5911-3 and Kitemarked, and Precast concrete gully risers to BS 5911-6 and Kitemarked