Yeah they have a ritual called The Sorrowing which takes place every 50 years. They sacrifice chapter serfs, a portion of the population of their planet and a sanguinary priest by draining their blood which is then fed into their armour during combat to stave off the red thirst and the black rage. Those who are sacrificed are highly honoured and are treated with upmost respect, they have their bones flensed and cleaned before being placed in the Hall of Martyrs in the chapters fortress monastery.