Prayers to Vulcanus
As I wrote earlier, prayers to Vulcanus are scarce in Roman literature. However there is mention of a charm where He is invoked to ward off fires from a home. It was very common for Roman houses to have such charms, so He was more important than our sources indicate. I'll have to see if I can recover that. These, however, are the only prayers I have found thus far.
Grattius Faliscus Gynegetica 437-42
Holy Vulcanus, foremost of those who cherish this place, to You we pray for peace. Grant Your ultimate assistance to the tired and worn, and, if no one here merits punishment for some noxious crime, may You have mercy on all their souls and allow them to reach Your purifying fountains. Three times they invoke Your name, three times they pour rich incense upon the focal fire, and strew the altar with auspicious boughs in Your honor.
Martial Epigrammata 5.7.5 To Vulcan
Soon, I pray, Vulcan, memories of whispered rumors of disgrace and loud quarrels of complaint You will no longer hold against the children of Mars; we are also the children of Your sweet wife Venus, spare us, Father.