ISO 21593:2019 pdf download – Ships and marine technology – Technical requirements for dry- disconnect/ connect couplings for bunkering liquefied natural gas
1 Scope
This document specifies the design, minimum safety, functional and marking requirements, as well as the interface types and dimensions and testing procedures for dry-disconnect/connect couplings for LNG hose bunkering systems intended for use on LNG bunkering ships, tank trucks and shore-based facilities and other bunkering infrastructures. It is not applicable to hydraulically operated quick connect/disconnect couplers [QCDC] used for hard loading arms, which is covered in ISO 16904.Based on the technology used in industrial manufacturing at the time of development of this document,it is applicable to sizes of couplings ranging from DN 25 to DN 200.
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 amendment) applies.
ISO 3834 (all parts), Quality requirements for fusion welding of metallic materials
ISO 5208:2015, Industrial valves – Pressure testing of metallic valves
EN 1092-1, Flanges and their joints
EN 12266-1:2012, Industrial valves – Testing of metallic valves – Part 1: Pressure tests, test procedures and acceptance criteria – Mandatory requirements
ASME B16.5-2009, Pipe flanges and flanged fittings
ASME B31.3-2018, Process piping
4.4.5 The design of the coupling shall allow the coupling to be manually connected and disconnected unaided and the maximum force to (dis)connect the nozzle from the receptacle shall not exceed 350 N. Where this force exceeds 350 N, actuation shall be pneumatically or hydraulically assisted.
The nozzle shall be so designed as to be operated without the use of tools (e.g. extension bars) and excessive force for connecting and disconnecting.
4.4.6 The operation direction to open and close shall be indicated with an indelible mark. Connected condition shall be made with a positive indication that the mechanism action is fully made.
4.4.7 The design of the nozzle and receptacle shall allow for the removal of liquid and vapour before disconnection, avoiding vapour and liquid trapped in the dead space during purging operation.
4.4.8 The nozzle shall have an integrated swivel function. It shall allow free rotation, to prevent the application of torsional loads on the bunkering system.
4.4.9 The coupling shall have suitable fire resistance properties and shall be fire type tested in accordance with recognized standards (e.g. ISO 10497).
4.4.10 The coupling shall be made of conductive, non-sparking material.
8.5.1 The shell tightness test shall be carried out according to ISO 5208 or EN 12266-1 P11 or equivalent. The purpose of this test is to confirm the leak tightness of the shell, including the connection sealing against internal pressure.
8.5.2 The coupling shall be pressure-tested with dry gas at least at 0,03 MPa and followed by a pressure of 0,6 MPa. The test pressure shall be maintained for a duration not less than the periods specified in 8.2.2.
8.5.3 Acceptance criteria is that the coupling shall be tight without visually detectable leakage for the duration of the test. No continuous formation of bubbles is permitted when the coupling is coated with a leak detection fluid.