5.2.4 Holes in joint surfaces
Where a plane joint or the plane part or partial cylindrical surface (see 5.2.6) of a joint is
interrupted by holes intended for the passage of threaded fasteners for assembling the parts of
a flameproof enclosure, the distance l to the edge of the hole shall be equal to or greater than
– 6 mm when the width of joint L is less than 12,5 mm,
– 8 mm when the width of joint L is equal to or greater than 12,5 mm but less than 25 mm,
– 9 mm when the width of joint L is equal to or greater than 25 mm.
The distance I is determined as follows.
5.2.4.1 Flanged joints with holes outside the enclosure (see Figures 3 and 5)
The distance l is measured between each hole and the inside of the enclosure.
5.2.4.2 Flanged joints with holes inside the enclosure (see Figure 4)
The distance I is measured between each hole and the outside of the enclosure.