Final answer:
Authorized personnel, who may be certified welders, licensed professionals, or trained technicians with the specific certifications, are permitted to weld gas piping. The exact qualifications depend on regional legislative and safety requirements.
Step-by-step explanation:
The individuals who are permitted to weld gas piping are typically those with specific qualifications and legal authorization, which can vary by region. In general, the correct answer is d. Authorized personnel. This term encompasses those professionals who have met the necessary legal and professional standards to carry out such a specialized task. This group can include certified welders, licensed professionals, or trained technicians who have been specifically certified to weld gas piping.
The authorities or governing bodies that oversee plumbing and gas fitting work will set the standards for who is authorized. These professionals must be aware of the technical and safety protocols in dealing with potentially hazardous materials such as gas. Therefore, they are typically required to have relevant certifications and to adhere to strict compliance standards set by safety codes and industry regulations.