Section 59.10-15 - Rivets and staybolts(a) It is not permitted to reinforce or build up by welding the heads of rivets or staybolts that have deteriorated. Such rivets or staybolts must be replaced. The seal welding of rivet heads to secure tightness is prohibited.(b) Where leaks develop around staybolts which are otherwise in good condition, the nuts may be replaced with a beveled collar formed around the end of the stay by means of welding. In such cases, the depth of collar measured on the stay and the width measured on the plate, must be equal to one-half the diameter of the staybolt.