Which factor is essential for ensuring the integrity of a welded joint according to API 1104?

Proper documentation and inspection are essential for ensuring the integrity of a welded joint according to API 1104. This factor emphasizes the importance of maintaining detailed records throughout the welding process, including the specifications of the materials used, the qualifications of the welding personnel, and inspection reports.

Documentation serves as a critical reference that validates compliance with industry standards and codes, confirming that all procedures were followed correctly. Proper inspection processes are vital for identifying any defects or potential issues in the weld before the pipeline is put into service. This proactive approach helps in preventing failures that could lead to significant safety hazards, environmental concerns, or costly repairs in the future.

While temperature control, the choice of skilled workers, and the cost of materials can influence the welding process, they do not encompass the broader scope of quality assurance that documentation and inspection provide. These aspects are important, but without thorough documentation and inspection, the integrity of the welded joint cannot be confidently assured.