Final Answer:
Where a hardness limit is specified in table 331.1.1, at least 10% of welds, hot bends, and hot-formed components in each heat-treated batch, and 100% of those locally heat-treated shall be tested.
Step-by-step explanation:
The specification of hardness limits in welding standards is crucial for ensuring the structural integrity and quality of welds, hot bends, and hot-formed components. The requirement to test a certain percentage of these components is a measure to guarantee compliance with the specified hardness limits. In this context, the 10% testing mandate means that a representative sample from each heat-treated batch must undergo hardness testing, and at least 10% of the welds, hot bends, and hot-formed components should meet the hardness criteria outlined in table 331.1.1.
Hardness testing involves determining the resistance of a material to indentation or penetration. The specified limit in table 331.1.1 serves as a threshold to prevent issues such as brittleness or inadequate strength in the welded joints or formed components. The 10% sampling requirement is a statistically significant approach to ensure that the tested samples are representative of the entire batch. This practice helps identify any variations or anomalies in hardness within the heat-treated batch, allowing for corrective actions and ensuring that the majority of components meet the specified hardness criteria.
Furthermore, the 100% testing requirement for locally heat-treated components emphasizes the critical importance of verifying the hardness in these specific areas. Locally heat-treated regions may experience different metallurgical changes, and comprehensive testing ensures that these areas meet the specified hardness limits without compromising the overall structural integrity of the welded components.