What is required between the steam outlets of two connected boilers?

In a system where two boilers are connected on the steam outlet, the installation requires two stop valves with a free blow drain in between them. This configuration is crucial for a couple of reasons.

Firstly, having two stop valves allows for maintenance and repair of either boiler without interrupting the operation of the other. This is particularly important in a continuous operation environment, as it ensures that one boiler can be isolated while the other remains operational. The ability to shut off the steam flow from either boiler increases system flexibility and reliability.

Secondly, the inclusion of a free blow drain ensures that any condensate that accumulates in the piping between the two stop valves can be safely and effectively drained away. Accumulated condensate can lead to water hammer, reduced efficiency, and potential damage to the system. A free blow drain allows for the effective removal of this condensate, maintaining optimal operating conditions.

Therefore, the requirement of two stop valves with a free blow drain is based on operation safety, ease of maintenance, and the prevention of potential operational issues that could arise from condensate accumulation. This setup is designed to enhance the overall efficiency and safety of the boiler system.