BS ISO 13733:2020 Ships and marine technology — Ship’s mooring and towing fittings — Universal fairleads with upper roller.
1 Scope
This document specifies the types, nominal sizes, dimensions and materials, as well as construction, manufacturing and marking requirements, for universal fairleads with upper roller(s) installed to lead the mooring rope of a ship.
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.
IMO Circular MSC/Circ.1175, Guidance on shipboard towing and mooring equipment
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
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safe working load
safe load limit (maximum permissible load) of the fittings used for mooring and towing
4 Classification
4.1 Type
Depending on the construction, universal fairleads shall be classified as belonging to one of the following four types:
a) Type 4R: with one rope-passing opening;
b) Type 5RL: with one rope-passing opening with an additional guide roller on the left side;
c) Type 5RR: with one rope-passing opening with an additional guide roller on the right side;
d) Type 7R: with two rope-passing openings.
4.2 Nominal sizes
The nominal sizes, D n , of universal fairleads are denoted by reference to the outside diameter of the main roller, in millimetres, in terms of the nearest number drawn from a basic series of preferred numbers. For the universal fairleads having the same roller diameter, the code, i.e. 4R, 5RL, 5RR or 7R, is followed by the nominal size for the different SWLs.BS ISO 13733 pdf download.