Why is it important to have a seam above the fire line in the boiler?

Having a seam above the fire line in a boiler is essential to avoid overheating and potential failure. The fire line refers to the level of the highest heat exposure within the boiler, where combustion gases and heat are concentrated. If seams are positioned below this line, they are subjected to extreme temperatures, which can lead to material degradation, warping, or failure due to thermal stresses.

By placing seams above the fire line, the risk of overheating the structural components of the boiler is significantly reduced. This positioning helps maintain the integrity of the boiler under operational conditions, ensuring that it can safely handle the pressure and thermal variations without compromising its safety or structural reliability.

While increasing safety during operation, enhancing structural integrity, and allowing for easier inspections are important considerations, the primary reason for situating seams above the fire line fundamentally revolves around mitigating overheating risks and preventing potential catastrophic failures.