2 Essential joints, such as bolts, rivets, etc., shall be seated on the outside, protrude
on the inside and be bolted, riveted or welded in a satisfactory manner. If the bolts
holding the essential parts of the sides, floor and roof are seated on the outside,
the other bolts may be seated on the inside, provided that the nut is properly welded
on the outside and is not covered with non-transparent paint. However, by analogy
with provisions regarding railway wagons, the following conditions shall apply to
containers conveyed exclusively by rail under Customs seal: essential joints, such
as bolts, rivets, etc., shall, where practicable, be seated on the outside, and shall
be bolted, riveted or welded in a satisfactory manner. Where it is necessary for bolts
to be seated on the inside with securing nuts on the outside, the bolt ends shall
be riveted or welded over the nuts.