What type of stays are used in the heads of water tube boilers?

In water tube boilers, the design typically allows for the elimination of stays in the heads. The structural design of these boilers enables the use of water-filled tubes to provide the necessary strength and support, which eliminates the need for additional stays. Stays are generally applied in the construction of certain types of boilers that need extra support. However, in the case of water tube boilers, their construction and operation allow them to withstand internal pressures without external supports like stays. This design enhances their efficiency and safety, making the option of no stays the correct choice.