11.5 Fasteners shall not pass through the walls of a flameproof enclosure, unless they form a
flameproof joint with the wall and are non-detachable from the enclosure, for example by
welding, riveting or an equally effective method.
11.6 In the case of holes for screws or studs which do not pass through the walls of
flameproof enclosures, the remaining thickness of the wall of the flameproof enclosure shall be
at least one-third of the nominal diameter of the screw or stud with a minimum of 3 mm.
11.7 When screws are fully tightened into blind holes in enclosure walls, with no washer fitted,
at least one full thread shall remain free at the base of the hole.
11.8 If, for ease of manufacture, a wall of a flameproof enclosure has to be drilled through,
the resulting hole shall subsequently be closed by a device so that the flameproof properties of
the enclosure are maintained. This device shall be securely fixed in accordance with the
requirements of 11.4 for studs.
11.9 If apertures provided in a flameproof enclosure (for example, for cable gland or conduit
entry) are not used, they shall be closed so that the flameproof properties of the enclosure are
maintained (see Figure 22 for examples).
The closing device may be made so that it can be fitted or removed from either the outside or
the inside of the wall of the flameproof enclosure.
The mechanically or frictionally locked blanking element shall comply with one or more of the
requirements of 11.9.1 to 11.9.3.
11.9.1 If the closing device is removable from the outside, this shall be possible only after
disengagement of a retaining device inside the enclosure (see Figure 22a).
11.9.2 It may be so designed that it can be fitted or removed only by the use of a tool
complying with the requirements of 9.2 of IEC 60079-0 (see Figure 22b).
11.9.3 It may be of a special construction in which insertion is carried out by a method other
than that used for removal. Removal shall only be by one of the methods specified in 11.9.1 or
11.9.2 or by a special technique (see Figure 22c).
11.10 Separate fastening arrangements that require the use of a tool of the type required
in 9.2 of IEC 60079-0, or the use of some equally effective methods, shall be provided to
secure and release threaded doors or covers.