Maintenance is etymologically related to Maintain. Maintain is related to Preserve. Preserve is related to Intact. Intact is a synonym of Entire. 
Steel is related to Safe. 
Maintenance --EtymologicallyRelatedTo--> Maintain <--RelatedTo--> Preserve <--RelatedTo--> Intact <--Synonym--> Entire 
Steel <--RelatedTo--> Safe 