2.2 Mechanical design standards
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.677 – Revised Standards for the Design, Testing and Locating of Devices to Prevent the Passage of Flame into Cargo Tanks in Tankers – (Adopted on 30 December 1994)1 Amended by MSC/Circ.1009 - Annex - Revised Standards for the Design, Testing and Locating of Devices to Prevent the Passage of Flame into Cargo Tanks in Tankers - 2 Standards - 2.2 Mechanical design standards

2.2 Mechanical design standards

  2.2.1 The casing or housing of devices should meet similar standards of strength, heat resistance and corrosion resistance as the pipe to which they are attached.

  2.2.2 The design of devices should allow for ease of inspection and removal of internal elements for replacement, cleaning or repair.

  2.2.3 All flat joints of the housing should be machined true and should provide for a joint having an adequate metal-to-metal contact.

  2.2.4 Flame arrester elements should fit in the housing in such a way that flame cannot pass between the element and the housing.

  2.2.5 Resilient seals may be installed only if their design is such that if the seals are partially or completely damaged or burned, the device is still capable of effectively preventing the passage of flame.

  2.2.6 Devices should allow for efficient drainage of moisture without impairing their efficiency to prevent the passage of flame,

  2.2.7 The casing and element and gasket materials should be capable of withstanding the highest pressure and temperature to which the device may be exposed under both normal and specified fire test conditions.

  2.2.8 End-of-line devices should be so constructed as to direct the efflux vertically upwards.

  2.2.9 Fastenings essential to the operation of the device, i.e. screws, etc., should be protected against loosening.

  2.2.10 Means should be provided to check that any valve lifts easily without remaining in the open position.

  2.2.11 Devices in which the flame arresting effect is achieved by the valve function and which are not equipped with the flame arrester elements (e.g. high velocity valves) must have a width of the contact area of the valve seat of at least 5 mm.

  2.2.12 Devices should be resistant to corrosion in accordance with 3.5.1.

  2.2.13 Elements, gaskets and seals should be of material resistant to both seawater and the cargoes carried.

  2.2.14 The casing or housing should be capable of passing a hydrostatic pressure test, as required in 3.5.2

  2.2.15 In-line devices should be able to withstand, without damage or permanent deformation, the internal pressure resulting from detonation when tested in accordance with section 3.4.

  2.2.16 A flame arrester element should be designed to ensure quality control of manufacture to meet the characteristics of the prototype tested, in accordance with these Standards.

Parent topic: 2 Standards
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