【正文】 m finish. Vickers hardness measurements, using a 5 N test force, shall be carried out inwards from the intrados by a petent person, in accordance with the procedures in ISO 65071. Care shall be taken in selecting the longitudinal and lateral spacing of the test impressions to ensure that an accurate plot of hardness against position is obtained. The inward series of measurements shall be continued until it is apparent that a minimum hardness level has been reached. A reference line shall be constructed on the plot at a level equivalent to 20 points Vickers above the estimated core hardness. The position equivalent to the intersection of this reference line with the plot of hardness against position shall be considered as the total case depth. The estimated core hardness is the hardness measured at a position equivalent to 3 x 0,06 dn in from the outer surface. Each determination of case depth shall meet the requirements of . EN 8187:2020 (E) 16 max min Key 1 Transverse section 2 Diameter along which measurements are taken 3 X = Intrados Figure 4 — Hardness test for case depth determination, link arrangement Fatigue resistance test – Types DAT and DT. Three 5link samples shall be subjected to fatigue testing. The frequency of the stress applied shall be 5 Hz to 10 Hz, and the testing machine shall conform to ISO 4695 and Class 3 of EN ISO 75001. The stress level applied during each cycle shall be as follows: maximum stress level ( ) 200 N/mm2 mean stress level 120 N/mm2 minimum stress level ( ) 40 N/mm2 Each sample shall meet the requirements of . Samples which fail in the area of the machine grips shall be discarded and that test repeated. Type tests – Acceptance criteria The requirements of , and shall be met by each sample of each size and type of chain tested. For , and , if one sample fails to meet the requirements two further samples of the same chain shall be tested. If bo。 0,01) dn (0,04 177。 0,01) dn (0,05 177。 1,0 60 1,2 24,0 68,0 660 3,2 21,6 22 177。 0,6 48 0,9 19,2 54,4 528 2,5 17,3 18 177。 0,5 39 0,8 15,6 44,2 429 2,1 14,0 14 177。 0,4 33 0,6 13,2 37,4 363 1,7 11,9 12 177。 0,4 27 0,5 10,8 30,6 297 1,4 9,7 10 177。 0,3 21 0,4 8,4 23,8 231 1,1 7,6 8 177。 0,2 15 0,3 6,0 17,0 165 0,8 5,4 6 177。 technical delivery conditions (includes amendment A1:1993). ISO 643, Steels – Micrographic determination of the ferritic or austenitic grain size. ISO 43011, Cranes and lifting appliances – Classification – Part 1: General. ISO 65071, Metallic materials – Vickers hardness test – Part 1: Test method. ISO 4965, Axial load fatigue testing machines Dynamic force calibration Strain gauge technique. 3 Terms and definitions For the purposes of this European Standard the terms, definitions and symbols given in EN 8181 apply. EN 8187:2020 (E) 6 4 Hazards The release of a load due to failure of hoist chain puts at risk either directly or indirectly the safety or health of those persons within the danger zone of lifting equipment. In order to provide the necessary strength and durability of hoist chain, this European Standard lays down requirements for the design, selection of materials of construction and testing to ensure that specified levels of performance are met. Fatigue failure has not been identified as a hazard for type T chain when hoist chain selected according to annex B and having the specified levels of performance and design given in this European Standard is used in serial hoists. Fatigue failure has been identified as a hazard for hoist chains types DAT and DT used in power driven hoists. Therefore this European Standard specifies levels of design and performance, with particular reference to fatigue resistance. Since failure can be caused by the incorrect choice of grades and specification of lifting hoist chain this European Standard also gives the requirements for marking and the manufacturers certificate. Dimensional inpatibility between the hoist chain and mating parts of the hoist (chain wheel, chain guide and loading device) may lead to premature failure and this European Standard contains dimensional requirements for correct assembly and fit. Table 1 lists those hazards, which require action to reduce risk identified by risk assessment as being specific and significant for hoist chain of Grade T Types T, DAT, DT. Table 1 — Hazards and associated requirements Hazards identified in annex A of EN 1050:1996 Relevant clause of annex A of EN 2922:1991/A1:1995 Relevant clause/subclause of this standard Mechanical hazard due to inadequacy of strength } } } } } 5 6 7 (Types DAT, DT only) Fatigue failure and EN 8187:2020 (E) 7 5 Safety requirements General The hoist chains shall conform to the requirements of EN 8181. Dimensions General A selection of nominal sizes and dimensions is given in and . Other nominal sizes may be used, provided that nominal sizes shall not exceed the range specified in and that the dimensions and tolerances are calculated in accordance with annex A. Whilst the nominal link pitch pn is based upon 3 dn (where dn is the nominal size of the hoist chains) this may be varied but shall not exceed the limits 2,6 dn to 3,2 dn. The nominal link pitch pn shall be subject to the tolerances specified in annex A. NOTE Compatibility between the hoist chain and the mating parts of the hoist requires agreement on the nominal size and dimensions and on the distribution of tolerances between the chain manufacturer and the hoist manufacturer. Nominal size dn The nominal size shall not be below 4 mm or above 22 mm, a selection of nominal s