ISO 21711:2019 pdf free.Marine structures – Mobile offshore units- Chain wheels.
1 Scope
This document specifies the requirements for the profiles, dimensions, tolerances, materials and inspection of chain wheels for chains on mobile offshore units.
Chain wheels meeting the requirements of this document can be used with offshore mooring chains conforming to ISO 20438.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3828, Shipbuilding and marine structures — Deck machinery — Vocabulary and symbols ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 8062-3, Geometrical product specifications (GPS) — Dimensional and geometrical tolerances for moulded parts — Part 3: General dimensional and geometrical tolerances and machining allowances for castings
ISO 1 1971:—i), Steel and iron castings — Visual examination of surface quality ISO 16859-1, Metallic materials — Leeb hardness test — Part 1: Test method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3828 and the following apply.
ISO and TEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://wwwisoxg/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1 pitch diameter Dp circumscribed circle diameter of the regular polygon formed by the centerline of the stud-ink anchor chain where the anchor chain is engaged with the chain wheel
Note 1 to entry: Pitch diameter is used to calculate the maximum torque of the anchor chain during operation.3.2 speed calculation diameter Dv diameter of the moving line of the stud-link anchor chain when anchoring with power 4.2 Designation The designation of a chain wheel shall consist of the words “Chain wheel” followed by a space, a reference to this document followed by a space, the type of chain wheel (A, B or C) and the diameter (in mm) of the anchor chain. EXAMPLE The designation of a 5-tooth chain wheel with a diameter of the anchor chain of 56 mm is as follows: Chain wheel ISO 21711:2019 A56 5 Requirements 5.1 Geometric tolerance and dimensional tolerance
5.1.1 The linear dimensional tolerance of castings shall conform to ISO 8062-3, DCTG 11.
5.1.2 The geometric tolerance of castings shall conform to ISO 8062-3, GCTG 7.5.2 Materials
5.2.1 Materials used for chain wheels shall be selected according to the grade of offshore mooring
chains, such as R3, R3S, R4, R4S and R5. 5.2.2 The tooth surface hardness at the meshing zone of chain wheels shall be in line with the hardness of offshore mooring chains, and may be 10 % higher than the hardness of offshore mooring chains according to service conditions; the tooth surface hardness may achieved by heat treatment of materials or embedding wear-resistant materials into the meshing zone. 6 Inspection 6.1 Dimensional and geometric inspection Testing of linear dimensional tolerance and geometric tolerance shall meet the requirements of 5.1.1 and 5.1.2.
6.2 Visual inspection for surface quality The visual inspection for the surface quality shall comply with the requirements of ISO 11971:- _2), Clause 4. 6.3 Inspection of tooth surface hardness The tooth surface hardness shall be inspected according to ISO 6506-1 or ISO 16859-1. 6.4 Material inspection
The product inspection certificate issued by the classification society shall be provided for chain
wheel blanks. ISO 21711 pdf download.