int hours = (int)hoursDecimal;
decimal minutesDecimal = ((hoursDecimal - hours) * 60);
int minutes = (int)minutesDecimal;
int seconds = (int)((minutesDecimal - minutes) * 60);

trunc(mod(dec, 1)) => hours
trunc(mod(dec * 60, 60)) => minutes
trunc(mod(dec * 3600, 60)) => seconds

int seconds = (int) ((dec * 3600) % 60)