BS 65: 1988 pdf download.Vitrified clay pipes, fittings,joints and ducts.
4. Materials and manufacture 4.1 Pipes and fittings. Pipes and fittings shall be made from suitable clays and when fired shall be sound and free from such defects as would impair their function when in service. Pipes and fittings may be unglazed, or glazed on the interior and/or exterior. When glazed, they need not be glazed on the jointing surfaces of the spigot and socket. Pipes and fittings marked as 'Duct' shall not have sharp ends to the internal barrel. Fittings may be completed by affixing fired parts together. Fired fittings may be surface treated after firing. They shall be deemed to comply with this standard provided that the completed fittings meet all the appropriate requirements specified in clauses 7 and 8.
4.2 Flexible mechanical joints
4.2.1 Each component shall be fabricated having regard to its individual function in such a way that the physical performance of the joint assembly in service will be maintained.
4.2.2 Elastomeric joint rings shall satisfy the physical property and type test requirements of rings of type D (drainage) specified in BS 2494.
5. Dimensions and tolerances
5.1 Bore. The bore of the barrel of a pipe shall not deviate from the nominal size given in the first column of table 1(a or table 1(b) beyond the limits of minimum and maximum shown.
5.2 Length. Preferred nominal lengths are not specified in this standard, but the limits of tolerance on the manufacturer's stated nominal length shall be:
(a) for normal pipes, extra chemically resistant pipes and ducts, -1 % +4 % subject to a minimum value of 土5mm;
(b) for surface water and perforated pipes, -2 % +5 % subject to a minimum value of土10 mm.
5.3 Straightness. When tested in accordance with appendix A, the permissible deviation from straightness of the barrel of a pipe of any nominal bore shall not exceed that specified in table 2.
5.4 Perforations. The holes in perforated pipes shall be either circular or slotted, and shall be cleanly cut. They shall be positioned in one 180。 segment of the barrel in one or more rows parallel to the longitudinal axis of the pipe, the holes in each row being spaced equidistantly. The permissible deviation of the spacing between the holes in any row shall not exceed土20 mm.
The total area of holes measured at the pipe bore shall be not less than 3 mm2 per millimetre nominal size per metre length. The diameter of circular holes at the pipe bore shall
be not greater than 10 mm. If slots are used instead of circular holes, the width of slot at the pipe bore shall be not greater than 8 mm.BS 65 pdf download.