|
TECHNICAL SPECIFICATIONS
Technical specifications of the SMS fittings are commonly based on the International Standard ISO 2531 , or its extensions. Those not specified in ISO 2531 are in conformity with British Standard BS 4772 or German Standard DIN 28604-48. The product range also covers some special fittings and the joint accessories.
MANUFACTURING METHOD
Fittings and ductile iron accessories are made of good quality materials using proper techniques to result in a casting in compliance with the requirements of international standards. They are cast in metal or in sand moulds, and may be subjected, if necessary to suitable heat treatment to give them the required mechanical characteristics. Special grades of ductile iron can be developed for the transport of certain particularly aggressive chemicals.
WALL THICKNESS AND DIMENSIONS
The wall thickness and the dimensions of the fittings are calculated as a function of their nominal diameter, DN, by the formula established in ISO 2531. The wall thickness may be adjusted to the mechanical stresses induced by internal pressure. Fittings with special wall thickness and dimensions may be supplied under agreement between the purchaser and the manufacturer.
TOLERANCES ON DIMENSIONS AND WEIGHT
The tolerances on wall thickness, dimensions and mass of the ductile iron fittings is in accordance with ISO 2531 at the purchaser's or manufacturer's option. The masses indicated for the SMS fittings have been calculated by taking the density of cast iron as 7050 kg/m3 in conformity with the standards.
JOINTS Flexible Joints
Flexible joints, either of the push-on type the mechanical type, used to connect the socket of one component to the spigot of the other, will be in accordance with manufacturer's standard dimensions and tolerances. The standart push-on joint, Type S, has a deep recess with angular seating faces for the gasket. The Iong cavity in the socket allows for angular and Iongitudinal movements of the adjoining pipes.
The mechanical joint, Type K, is secured by means of a gland compressing the gasket Iocated in the socket. For being used as a dismantling component in pipe Iines, mainly the sliding collars of SMS have K- Type joints. On request mechanical joints can be applied to other fittings.
Flanged Joints
SMS fittings are designed for normal working pressures and their flanges are available in PN 10, PN 16, PN 25 and PN 40 standard driIlings in conformity with ISO 2531. Flanges in accordance with other international or national standards may also be supplied on request.
LININGS AND COATINGS
The coating is done by utilising one of the most environmentally compatible technology available for surface treatment: Electrostatic Powder Coating. Epoxy resin coating, applied both to internal and external surfaces, have a very good chemical resistance and excellent mechanical properties such as high resilience, impact strength, moldability and resistance to solvents, acid and alkali. Epoxy resin powders are physiologically safe and even used in the food industry.
When necessary or requested, the conventional technique that consists of application of interior cement mortar exterior zinc Iinings, and final bitumen coating on the outside, is also possible.
Cement mortar applied to inner surfaces of the fittings by hand, is cured to achieve uniform surface quality. Finished cement mortar Iining guarantees smooth water flow and protects the fittings against corrosion.
Electrolytic zinc protection is ensured by the sprayed Iining.
ACCESSORIES Rubber Gasket for Push-on Joint
The rubber gaskets for push-on type joints are made of synthetic rubber (sytrene butadien rubber; SBR). Sectional profile of the gasket is dependent on diameter as given in the technical data sheets.
Mechanical Joint Accessories
The rubber gaskets for mechanical type joints are made of SBR. The gland, bolts and nuts will be in accordance with the manufacturer's standards.
Flanged Joint Accessories
The gaskets for flanged joints are made of fiber reinforced SBR with a thickness in accordance with the manufacturer's standards. Hexagon head bolts with hexagon nuts for the flange will be made of mild steel, and galvanised, unless otherwise stated by the purchaser.
|
