At the start of each of his turns, before doing anything else, the controlling player must declare how many Steam Points (SP) his Steam Tank is trying to build up (ie, how much pressure he's going to create in the boiler). You can declare anything between 0 and 5 SP.

Roll a dice for each Steam Point you are building up and total up the results of the dice rolled. If the total is equal to or less than the Steam Tank's current Hull Points, all is fine and you generate the SP you wanted. If you roll above the current Hull Points, the SP are generated but something has gone wrong and you have to roll a dice on the Malfunction chart and apply the result immediately.

It is a good idea to place a dice on top or near the Tank to record how many SP it has available. As you use them throughout the turn, deduct the number of SP available by turning the dice so that it shows the SP remaining.