IEC / BS EN60079-14 states that the obstruction of flanged joints must be avoided, unless the equipment has been tested at smaller distances than those shown in the table below.
A solid object such as a wall, steelwork, conduit, bracket, or other equipment etc., in close proximity to the opening at the joint can, in the event of an internal explosion, reduce the efficiency of the flamepath to the extent that ignition of the external gas could occur.
The minimum separation distances between the flamepath opening and an obstruction, as specified in 60079-14 are:
| Gas Subdivision | Distance |
| IIA | 10mm |
| IIB | 30mm |
| IIC | 40mm |
