Daniel Sargent, 26, was convicted after being charged with driving with 107mcg of alcohol per 100ml of breath in his system.
At about 8.30pm on June 24, police said officers received reports of a white Mercedes Sprinter being driven erratically on the A27 westbound through Arundel.
Police said the van continued on the dual carriageway towards Chichester, before it turned into an industrial estate where it was abandoned.
Officers said they found the suspect down an alleyway a short time later, at which point he placed his van key in his mouth and attempted to swallow it.
Concerned for his welfare, police restrained the man and made him spit out the key.
After failing a roadside breath test, he was then arrested on suspicion of drink-driving.
The legal limit is 35mcg.
At Worthing Magistrates’ Court on 11 July Sargent, a courier of East Cosham Road, was disqualified from driving for 24 months.
He was also ordered to carry out 100 hours of unpaid work, and pay £85 costs and a £85 victim surcharge.