Cast iron can be used for boiler construction up to which pressure?

Cast iron is known for its strength and durability, but it also has limitations when it comes to pressure applications. It can typically be used for boiler construction in low-pressure systems. The maximum allowable pressure for cast iron boilers is generally recognized as 100 kPa, which aligns with standard regulations in the industry.

At pressures above this threshold, the risk of failure increases significantly due to the material's brittleness and susceptibility to cracking under stress. Thus, utilizing cast iron in high-pressure applications can be dangerous, which is why the maximum limit is set at 100 kPa. This ensures safe operation and structural integrity of the boiler system.

In contrast, higher pressures such as those listed in the other options would necessitate materials that can withstand greater stress and thermal expansion, making them unsuitable for cast iron use.