BS EN 969:2009 pdf download – Ductile iron pipes, fittings, accessories and their joints for gas pipelines — Requirements and test methods
The standardized nominal sizes DN of pipes and fittings are as follows: 40, 50, 60, 65, 80, 100, 125, 150, 200, 250, 300, 350, 400, 450, 500 and 600. Annexes A and B, respectively, give the longitudinal bending resistance and the diametral stiffness of ductile iron pipes.
NOTE 2 The maximum allowable pressure for gas application is 16 bar which gives a mechanical safety factor of at least 2,25 * 3 = 6,75 for the DN 600 or more for smaller diameters (see Annex A of EN 545:2006 for the calculation method).
NOTE 3 When installed and operated under the conditions for which they are designed (see Annex C and Annex D), ductile iron pipes, fittings, accessories and their joints maintain all their functional characteristics over their operating life, due to the constant material properties, to the stability of their cross section and to their design with high safety factors.
4.1.2 Surface condition and repair Pipes, fittings and accessories shall be free from defects and surface imperfections which could lead to noncompliance with Clauses 4 and 5. When necessary, pipes and fittings may be repaired, for example by welding, in order to remove surface imperfections and localized defects which do not extend through the entire wall thickness, provided that:
the repairs are carried out according to the manufacturer’s written procedure;
the repaired pipes and fittings comply with all the requirements of Clause 4 and Clause 5.
4.1.3 Types of joints and interconnection General Rubber gasket materials shall comply with the requirements of EN 681-1 or EN 682 depending on air or gas. When materials other than rubber are necessary (e.g. for flanged joints), they shall comply with the appropriate European Standard or, where no European Standard exists, the appropriate International Standard. Flanged joints Flanges shall be constructed in such a way that they can be attached to flanges whose dimensions and tolerances comply with EN 1092-2. This ensures interconnection between all flanged components (pipes, fittings, valves, etc.) of the same PN and DN and adequate joint performance. Bolts and nuts shall comply as a minimum with the requirements of EN ISO 4016 and EN ISO 4034 (grade 4.6). Where washers are required, they shall comply with EN ISO 7091. Although it does not affect interconnection, the manufacturer shall state in his catalogues whether his products are normally delivered with fixed flanges or adjustable flanges.
NOTE Flange gaskets may be one of any type given in EN 1514. Flexible joints Pipes and fittings with flexible joints shall comply with for their spigot external diameter DE and their tolerances. This offers the possibility of interconnection between components equipped with different types of flexible joints. In addition, each type of flexible joint shall be designed to fulfil the performance requirements of Clause 5.
NOTE 1 For interconnection with certain types of joints operating within a different tolerance range on DE, the manufacturer’s guidance should be followed as to the means of ensuring adequate joint performance at high pressures (e.g. measurement and selection of external diameter).
NOTE 2 For interconnection with existing pipelines which can have external diameters not in compliance with, the manufacturer’s guidance should be followed as to the appropriate means of interconnection (e.g. adaptors). NOTE 3 If components of different suppliers are used, care should be taken to ensure that the requirements of the performance tests are met.
4.2 Dimensional requirements
4.2.1 Wall thickness
The nominal iron wall thickness of pipes and fittings shall be calculated as a function of the nominal size, DN, by the following formula ( K class formula), with a minimum of 6 mm for pipes and 7 mm for fittings:
e is the nominal wall thickness, in millimetres;
DN is the nominal size;
K is a coefficient used for thickness class designation. It is selected from a series of whole numbers: e.g. 8, 9, 10, 11, 12, etc.BS EN 969 pdf download.