Numeral 7.1.10.2 API 661 says: “The components of the nozzle loadings on a single header shall not exceed the following values.”

After analyzing the results given by the CAESAR module for API 661 I understood that the loads and moments are been summed in the center of the header, so that the single loads generate new moments that have been calculated at this point. Anyhow Cesar does this only for a header with two nozzle (inlet, outlet).

I need to do this analysis for a header with 4 nozzles, I want anybody to confirm if in this case I need to calculate the new moments at the geometrical center of such header and that this calculation can not be done by CAESAR.

What happens with numeral 7.1.10.3? “The total of all nozzle loads on the multi-bundle bay shall not exceed 3 times that allowed for a single header”
Where do I resolve the loads and moments sum?

API 661 is not very clear about the summation of loads and moments.

You don't need to resolve. Simply take the algebraic sum