BS EN 476:2011 pdf download – General requirements for components used in drains and sewers
5.3.4 Inspection chambers
Inspection chambers having DN/ID’s less than 800 permit the introduction of cleaning, inspection and test equipment, but do not provide access for personnel.
5.4 Interconnection Product standards shall state whether or not components within dimensional series (or tolerances) are capable of interconnection. Where such interconnection is not confirmed, product standards shall specify which means (e.g. adaptors) are required to effect interconnection.
6 Performance requirements
6.1 Mechanical resistance of pipes and fittings
6.1.1 Mechanical strength of pipes and fittings in the cross section
Mechanical strength requirements according to Table 4 shall be specified in product standards. Depending on the material, additional requirements can be necessary.
Pipes and,where appropriate, fittings shall be classified according to their characteristic structural behaviour.This behaviour can depend on:
— the material, particularly its ability to either deform, and/or crack and/or rupture at failure under load;
—the geometry, diameter, shape and wall thickness;
— the internal pressure in service (if applicable);
— the mechanical characteristics of the surrounding materials and support, after installation.
The load bearing capacity of components shall take into account all their relevant factors for safe and reliableoperation in systems, in particular:
— the minimum and maximum operation temperatures and the temperature-induced loads;
— the effects of constant or variable long term loading on the material properties;
—the effects of potential hazards such as ground subsidence;
—the effects of buoyancy, where it may occur.
As such,product standards shall specify:
Product standards shall state methods by which resistance to internal and external loadings is assessed. This can be specified by crushing strength test, maximum load deformation test, internal and external pressure strength tests or by calculation. Values shall be declared. Pipes can be defined as “flexible”, “semi-rigid” or “rigid” as defined in Clause 3. The failure load for flexible, semi-rigid or rigid pipes causes excessive deformation or rupture or unacceptable cracking of the pipes and can lead for example to: buckling of the wall, significant creep in the material, unacceptable cracking of coatings, loss of tightness in joints and reduction in hydraulic capacity.
6.1.2 Longitudinal bending moment resistance Long rigid or semi-rigid pipes of small diameters shall have a satisfactory longitudinal bending moment resistance. The values shall be specified in product standards and expressed in kN/m (see 7.3).
6.2 Mechanical resistance of manholes, shafts and inspection chambers above the base unit
6.2.1 General For manholes and inspection chambers appropriate strength requirements shall be specified in product standards. Mechanical behaviour of manholes can be specified by testing and/or calculation taking into account the long term behaviour. Crushing strength (kN/m), and/or axial load (kN/unit) and/or ring stiffness (kN/m 2 ) classes if more than one, shall be separated by at least 20 % of the next lower class.
6.2.2 Circular sections Circular sections shall have minimum crushing strengths and/or stiffness values, whichever is applicable, stated in product standards (see Rigid circular sections shall have a minimum crushing strength of 25 kN per metre length per metre internal diameter for nominal sizes less than or equal to DN 1000. For nominal sizes greater than DN 1000 the minimum crushing strength shall be 25 kN per metre length, or 30 kN per metre length if tested in a vertical position (see Flexible circular sections for use in carriageways, hard shoulders and parking areas shall have a minimum initial stiffness value of 2,0 kN/m 2 .
6.2.3 Other shapes Requirements for other shapes of construction shall be comparable to the requirements of 6.2.2 (see also
6.2.4 Tapers, reducing and cover slabs Requirements for tapers, reducing and cover slabs shall be specified in product standards. Tapers for manholes shall withstand the test load in accordance with EN 124 according to their place of installation (see
Reducing slabs for manholes shall withstand an ultimate load of at least 300 kN or a proof load of 120 kN (see when used in carriageways, hard shoulders and parking areas.