DIN Standards Committee Round Steel Link Chains
Round steel link chains - Round steel link chains, pitch 2,8d, for chain conveyors, grade 3, quenched and tempered
Rundstahlketten - Rundstahlketten, Teilung 2,8d, für Kettenförderer, Güteklasse 3, vergütet
About the history of DIN 766: DIN 766:1954 covered a variety of different chain types, such as tested, calibrated and tested, non-calibrated round steel link chains of grades 2 and 3 as well as chains which had not been tested. This had repeatedly led to confusion in the past. Therefore, further work on this topic was aimed at developing standards for the individual chain types. A first step was taken in 1980, when medium tolerance (non-calibrated) round steel link chains of grade 2 (formerly referred to as standard grade) were included in DIN 32891 after conversion to a ratio of nominal diameter to nominal pitch of 1:3. As a result, since 1986 chains as specified in DIN 32891 have had to be used for chain slings conforming to DIN 695. Upon revision of DIN 766:1954 in 1986, the scope was limited to close tolerance (calibrated) round steel link chains of grade 3 (formerly designated "quenched and tempered") which, in all sectors of industry, are preferably used as load chains, as hand chains in hand powered lifting equipment, and as long-link chains in chain conveyors and bucket elevators. For this reason, the values of pitch and width were not changed. Since then, close tolerance (calibrated), round steel link chains of grade 2 (formerly referred to as standard grade) have no longer been dealt with in DIN 766. They were included in other standards at a later date (a list can be found in the current draft standard). The next step towards separation was taken in 1990 with the publication of draft Standards E DIN 766-1 to -3. Part 3 included tested, close tolerance (calibrated) round steel link chains of grade 2 (formerly referred to as standard grade), with specific requirements for case hardening and with tolerances on length for matched chain strands, intended for use in bucket elevators. The actual specification was incorporated in DIN 5698-1 in 2001. Part 1 included rough tolerance round steel link chains, not tested, mainly used for subordinate purposes, such as barriers, or to hold and secure parts. For systematic reasons, this part became DIN 5685-3 later in 2003. Part 2 included tested, close tolerance (calibrated) round steel link chains of grade 2 (formerly referred to as standard grade). This part then formed the basis for preparing European Standards on studless anchor chains for use in inland navigation, since the mechanical properties of grade 2 chains (formerly referred to as standard grade) were in compliance with the regulations of the Germanischer Lloyd for quality grade GL-K1. The addition of further quality grades (GL-K2 and GL-K3) then led to the publication of DIN EN 14330 in 2004. Chains for hoisting equipment as in DIN 766:1986 have been dropped without replacement. Based on the specifications of DIN EN 13157, hand powered lifting equipment is now to be used with hoist chains of quality class T (type T) as in DIN EN 818-7, made of high-grade steels in accordance with DIN 17115. For power driven hoists as specified in DIN EN 14492-1 and -2, hoist chains of quality class T (types T, DAT and DT) as in DIN EN 818-7, made of high-grade steels in accordance with DIN 17115 are to be used. Hand chains for hand powered lifting equipment have been dropped and are now included in DIN 32898. Thus, the present standard DIN 766 only applies to tested, close tolerance round steel link chains of grade 3 for chain conveyors and bucket elevators. Therefore, this document applies to tested, close tolerance round steel short-link chains of grade 3, with a nominal pitch t = 2,8×d and with nominal diameters d from 10 mm to 42 mm, for use at service temperatures from -20 °C up to +400 °C. It specifies their dimensions and mechanical properties. Round steel link chains according to this document are preferably used as long link chains in chain conveyors and in bucket elevators, as defined in DIN 15201-1. To avoid confusion with round steel links chains of other grades, it shall be ensured before use that the chains bear the required test stamp. Round steel link chains as specified here shall not be used as lifting accessories, slings or loadbearing devices within the meaning of DIN 15003 in combination with cranes or hoists. This document has been prepared in close collaboration with the responsible department "Holz und Metall" ("Timber and metal"), division "Hebetechnik und Instandhaltung" ("Lifting technique and maintenance") of the Deutsche Gesetzliche Unfallversicherung (DGVU) (German Social Accident Insurance). It contains safety-related specifications by stating the ratios of operational to production-control to breaking stresses and, furthermore, by requiring that all round steel link chains are tested after production. This document contains in Clauses 5, 6, 8 and 10 specifications in terms of § 3 paragraph 2 of the Produktsicherheitsgesetz (ProdSG) (German Product Safety Law). Provided that DIN 685-2 has been determined by the product safety committee and its source has been made public in the "Gemeinsames Ministerialblatt" (Joint Ministerial Gazette) by the Bundesanstalt für Arbeitsschutz und Arbeitsmedizin (German Federal Institute for Occupational Safety and Health) it is assumed for "tested, tightly tolerated, short-linked round steel link chains of grade 3" produced according to this document that they meet the relevant requirements regarding safety and health of persons and hence comply with the generally accepted good engineering practice. This document has been prepared by NA 085-00-02 AA "Rundstahlketten, Einzelteile und Zubehör für allgemeine Zwecke" ("Round steel link chains, components and accessories for general purposes") of the Round Steel Link Chains Standards Committee (NRK) at DIN, the German Institute for Standardization. For further information about the NRK, visit us on the Internet under www.nrk.din.de.