Diamondrail
Chemical
- Jul 19, 2021
- 1
We are working through the calculations for a davit arm, type 2, type B according to Moss's Pressure Vessel Design Manual.
Our design is a NPS 3, SCH 160 Pipe with elbow, with a brace (stiffer). We ran the calculations without considering the stiffener, and combined stress are 0.99. (Considering we are using both impact factors on the lower end, the design fails, when we use the impact factors at the higher end: IE Cv = 1.8, and Ch = 0.5
Questions we have: 1) What are the criteria for choosing the impact factors within the ranges provided? Why choose a lower number or a number midway?
2) We did not see any formulas for the incorporation of the stiffer for the Type 2, and Type B davit arm designs? Nothing was shown anywhere. I understand it will help reduce bending/stress, how do we incorporate this and which formulas do we use?
Total weight of our davit/blind flange is about 825 Kg.
Our design is a NPS 3, SCH 160 Pipe with elbow, with a brace (stiffer). We ran the calculations without considering the stiffener, and combined stress are 0.99. (Considering we are using both impact factors on the lower end, the design fails, when we use the impact factors at the higher end: IE Cv = 1.8, and Ch = 0.5
Questions we have: 1) What are the criteria for choosing the impact factors within the ranges provided? Why choose a lower number or a number midway?
2) We did not see any formulas for the incorporation of the stiffer for the Type 2, and Type B davit arm designs? Nothing was shown anywhere. I understand it will help reduce bending/stress, how do we incorporate this and which formulas do we use?
Total weight of our davit/blind flange is about 825 Kg.
