BS ISO 13799:2020 Ships and marine technology — Ship’s mooring and towing fittings — Recessed bitts (casting type).
1 Scope
This document specifies the types, nominal sizes, dimensions and materials, as well as construction,manufacturing and marking requirements, for casting type recessed bitts to meet normal towing requirements.
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:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
safe working load
SWL
safe load limit (maximum permissible load) of the fittings used for mooring and towing
4 Classification
4.1 Type
Depending on the size and strength of the material, recessed bitts shall be classified as belonging to one
of the following six types:
a) Type 75: nominal size 850, casting material having a yield point of not less than 235 N/mm 2 ;
b) Type 110: nominal size 850, casting material having a yield point of not less than 350 N/mm 2 ;
c) Type 135: nominal size 850, casting material having a yield point of not less than 430 N/mm 2 ;
d) Type 100: nominal size 920, casting material having a yield point of not less than 235 N/mm 2 ;
e) Type 150: nominal size 920, casting material having a yield point of not less than 350 N/mm 2 ;
f) Type 180: nominal size 920, casting material having a yield point of not less than 430 N/mm 2 .
BS ISO 13799 pdf download.