Is adding a pipe branch by welding allowed only under certain conditions?

Welding a branch onto a pipe is a common practice in pressure piping systems, but it is subject to specific conditions to ensure safety and integrity. The correct answer emphasizes that this practice is permissible if the reinforcement of the branch connection has been properly evaluated.

This evaluation typically includes assessing the design and structural integrity of the connection, ensuring that it can withstand the pressures and stresses in the system. Proper reinforcement is crucial to maintain the strength and performance of the piping system, preventing issues such as leaks or potential failures.

In contrast, the other options suggest conditions under which welding might be completely restricted or rely solely on mechanical methods. However, while some regulations and standards may prefer mechanical connections for certain applications or specific situations, welding with adequate reinforcement is a recognized and accepted method in many instances within pressure piping practices. Hence, the emphasis on evaluation of reinforcement captures the essential safety considerations inherent in the welding process for branching pipes.