Which of the following is NOT a task typically performed by boilermakers?

Boilermakers are skilled tradespeople primarily involved in the fabrication, assembly, maintenance, and repair of boiler systems and related equipment. Their responsibilities often include constructing pressure vessels, which involve working with metal materials, ensuring they meet specific standards to contain pressure safely. Additionally, they also install insulation on boilers to improve energy efficiency and safety.

While repairing welding equipment could be a task they manage, it is not a core function that defines a boilermaker's role. Designing heating systems, however, typically falls under the purview of engineers or specialized technicians rather than boilermakers. This distinction is crucial; boilermakers focus on the physical construction and maintenance of equipment rather than the design aspects of system heating. Thus, the task of designing heating systems is not aligned with the standard duties of boilermakers, making it the correct answer in this context.