A major part of bridge maintenance is the requirement to change worn out "hot rivets" that play a crucial part in stabilising a bridge structure. These are particularly prevalent on traditional Victorian type bridge and viaduct structures.
Degraded or corroded rivets can be removed using the following techniques:-
Grinding off the head of the rivet then drilling out with a rotabroach; care must be given when cutting through each 'plys' as the residue of the cut steel called the slug will jam in the rotabroach and cause slow progress on drilling the remaining plys.
Another technique is a rivet buster which is a pneumatic power tool that cuts the head of the rivet then drives out the rivet body, care must be given to HAVS and rotation of the workforce must be considered.
Once the rivet is removed the hole is reamed out and a high friction bolt or tension control bolt (TCB) installed.
On a live structure rivetS should only be repalced on a one by one basis.