API 650 Tank Nozzle Load Allowable For Tank dia. Less Than 36mtr

Dear members, I have a question about the guidelines to follow for API 650 tank nozzle lad allowances. 1)The API 650 Appendix P states that ,this calculation is applicable to tank dia 36mtr and above,unless otherwise agreed by purchaser. My question for smaller diameter tanks, less than 36mtr dia. Does Appendix P is applicable for calculating allowable nozzle loads for API 650 ? 2)Appendix P provides two methods to calculate allowable nozzle loads,viz. by limiting the loads and by allowable stress? My question are these two methods are same ?or different?If different how does first method calculate limiting nozzle loads without having consideration of allowable stress in picture? 3)My third question if my vendor is stick to the clause as provided in requisition to follow API Appendix P for allowable nozzle loads ?how to make vendor convince to have increased nozzle load allowable. 4)the API tank in question need to be endorsed by PE as API 650 tank,the another method is to do FEA to check for higher allowables,but vendors PE tells than if not followed API 650 appendix p2,allowable nozzle load calc .,it will be difficult for him to endorse as API 650 tank as a PE? My question,if we do FEA for API 650 tanks do a PE can endorse the API650 certification for changed allowable nozzle loads? 5)my question-can we calculate allowable nozzle loads as per WRC 297 guidelines per API 650 Appendix P3 guideline s which could allow us to have higher allowable nozzle loads imposed by piping externally on the API 650 Tank nozzle? Your positive feedback is appreciated ASAP