According to Article 11.6 of GB 3836.2-2010, for non penetrationExplosion proofThe screw holes or double headed bolt holes on the shell wall, and the remaining thickness of the explosion-proof shell wall should be at least one-third of the diameter of the bolt or double headed bolt, with a minimum of 3mm.

Q： Does the 'remaining thickness' of the explosion-proof shell wall here refer to the thickness below the hole or the thickness around and below the hole?

A： The "remaining thickness" of the explosion-proof shell wall here is explained as follows: when the hole is perpendicular to the shell, only the shell wall below the hole has a thickness requirement (3mm or 1/3 diameter, whichever is larger). This explanation is based on the fact that there is no specific material thickness requirement for the explosion-proof shell, so the material around the hole is not restricted. Explosion proof testing should consider most blind holes, such as impact testing and overvoltage testing.