When MAWP is recalculated for piping systems of unknown materials, what information is used?

When MAWP is recalculated for piping systems of unknown materials, what information is used?

• A. The highest grade material and joint efficiency
• B. The service temperature rating
• C. The lowest grade material and joint efficiency in the applicable code
• D. The original manufacturer's name

Answer: (C)

When recalculating MAWP for piping systems with unknown materials, use the most conservative data available in the code: the lowest material grade and the lowest joint efficiency defined for the applicable code. This approach ensures the calculated MAWP reflects the weakest plausible combination of material strength and weld/fabrication quality, providing a safety margin if the actual material turns out to be weaker than expected. Temperature ratings and the manufacturer's name aren’t substitutes for selecting the material strength and joint efficiency; those values rely on known material properties and fabrication quality, which aren’t specified here.

When recalculating MAWP for piping systems with unknown materials, use the most conservative data available in the code: the lowest material grade and the lowest joint efficiency defined for the applicable code. This approach ensures the calculated MAWP reflects the weakest plausible combination of material strength and weld/fabrication quality, providing a safety margin if the actual material turns out to be weaker than expected. Temperature ratings and the manufacturer's name aren’t substitutes for selecting the material strength and joint efficiency; those values rely on known material properties and fabrication quality, which aren’t specified here.