Samuel Hemming was Titanic’s lamp-trimmer and responsible for providing all the lifeboats with lit oil lamps on the night of the disaster.
After the vessel struck an iceberg, Mr Hemming leapt out of bed and was informed by the ship’s designer, Thomas Andrews, the vessel would sink in 30 minutes.
He hurried below decks to the lamp room and used the keys to unlock the door to access the stock of lifeboat lanterns which he lit.
He brought the lamps up to the top deck four at a time, making five trips in total.
The dedicated crewman then set about making sure all 15 lifeboats had a lit lamp on them, making them easier for both survivors in the water and rescue ships to see.
After his job was done Mr Hemming, 43, plunged into the freezing water and swam 200 yards to a collapsible lifeboat which he was heaved into.
A short time later, the same boat saved about 30 men who were standing on the upturned hull of one of the main lifeboats.
Mr Hemming survived the 1912 disaster in which 1,522 people perished and kept the set of three keys for the rest of his life.
They were passed down through his family who sold them to a private collector more than 20 years ago.
He is now selling them at auction with a pre-sale |estimate of £60,000 at Henry Aldridge and Son of Devizes, Wilts.
Also for sale is a rare black and white photograph taken in 1912 showing Mr Hemming and 24 other Titanic crewmen in Washington for the US enquiry into the sinking. The photo is expected to fetch £5,000.
The auction takes place on March 31.