The project that I previously worked with was in its final stages of detailed design when a lot of discussions were undertaken on how to get along with construction people as they already started early works just after the release of approval from the Federal government for its Environmental Impact Studies.
In one of the discussions, I overheard one of the veteran engineers telling one of the young engineers that Engineering Standards are based on the experiences of those people who prepared them and they may not particularly affect a specific Engineering design.
The veteran engineer is correct. Engineering Standards are guidelines for Engineers with which complying with them will ensure that a design will be safe. It does not particularly follow that it will be economical though as Engineering Standards are deemed conservative.
An Engineering Design need not comply with standards as long as it could be supported by calculations that could determine that the design is safe. This is necessary that in case of an incident of failure of the design, there will be supporting documentation to support that it was a quality design.
One example of this is the failure of a conveying system supporting structure which caused disruption of production to the extent of millions of dollars. Not to mention, the cost of repairs.
Investigators found out that there was nothing wrong with the design itself. The cause of failure was a missing single bolt on one of the joints which after extended operations, the other bolts failed due to increased stress.
Engineering Standards are there to serve as guidelines for engineers to facilitate delivery but not necessarily to be complied with.