Originally Posted by wb47:
What function do staybolts server?
I'll give it a try. Staybolts support the firebox from the boiler wall providing the water jacket around the firebox. The worker was removing flexible staybolt covers and inspecting the bolt head, cup, seal and cover. Any worn, broken or badly rusted parts were being replaced with new parts, then a new cap was installed. The photos of the 838 staybolts in the roundhouse photos show similar cups, bolt heads and caps.
More info here