I thought repair is the first option and replace is done if cannot be repaired.
However, small equipment like those stated may be replaced on site straight away to reduce downtime and repair the kaput item on worshop's own time. So the repaired item be put back to inventory as reconditioned item.
Replacing field insutruments is probably common compared to repairing them.
What massive environmental impact does this repair or replace decision has? I guess all are dumped as scrapiron.
Is this a consultancy work or academic/student question?
Recycling scrap materials could be a lucrative business. There is a Chinese billionaire making his fortune from recycling construction materials and actively doing philantropic works now. I forgot his name.