This would be good in formats where evasion strategies are allowed, mainly VGC, where Ttar Chomp is a common strategy when both are legal (chomp doesn't always run veil powder but it can do it)
Other than that (let's assume a singles format for now), Chomp should not be the one setting Sand up (something like smooth rock Ttar/Hippo does a great job) and if you're truly commiting to evasion strats, SD is definitely better over Iron Head. Sandstorm can be replaced by a coverage move, but depending on the meta Stone Edge or Fire Fang are usually preferred.
Also, it is recommended to make and export the sets in Pokemon Showdown for the formatting and to check if your set if legal (in many singles formats like OU, this is not), and also put the format so people know what format this is for (it can be multiple, if applicable)