crabadan
Mechanical
- May 20, 2011
- 1
Hello people!
I'm a engineer of safety valves in Spain and now we want to enter in the "ASME WORLD" and I have some doubts, I explain my problem.
My problem is the following, I have 11 different types of orifices and I want to give an API letter to each one. I think I must select the API letter nearest to my area but I don’t really sure if I do it well.
For example, I have an orifice with diameter of 77 mm (3.031 in) the actual area of this orifice is: ACTUAL AREA = (?*77^2)/4= 4657 mm2 (7.218 in2). In this point start my doubt.
I don’t know if I have to select directly NOW the EFFECTIVE ORIFICE AREA of API 526 or I must do another calculation.
If I select the EFFECTIVE ORIFICE AREA of API with my ACTUAL AREA of 7.218 in2, this is letter P because in API 526 the nearest EFFECTIVE ORIFICE AREA is 6.38 in2 (P), correct?
OK, so consulting information in Internet, I have read that exists this a mathematical expression: K actual*A actual ? Kd effective (0.975) *A effective. If I do this mathematical expression with my K actual that is 0.78, I find this: A effective =(0.78*7.218 in2)/0.975= 5.775 in2.
If you go with this A effective to the API 526 you find that the nearest EFFECTIVE ORIFICE AREA is 4.34 in2 that is letter N.
As you can see, with the same initial diameter I find two different letters (P or N) and I don’t know what is the correct process. I don’t know if I have to select directly with my ACTUAL AREA an EFFECTIVE ORIFICE AREA of API 526 or on the contrary I must to transform my ACTUAL AREA to an EFFECTIVE ORIFICE AREA of API 526 with the Kd effective (0.975).
The design is ASME VIII but the center to face dimensions are according API 526, so I don't know if there is another standard that say you center to face dimensions.
Thank you for the help!
I'm a engineer of safety valves in Spain and now we want to enter in the "ASME WORLD" and I have some doubts, I explain my problem.
My problem is the following, I have 11 different types of orifices and I want to give an API letter to each one. I think I must select the API letter nearest to my area but I don’t really sure if I do it well.
For example, I have an orifice with diameter of 77 mm (3.031 in) the actual area of this orifice is: ACTUAL AREA = (?*77^2)/4= 4657 mm2 (7.218 in2). In this point start my doubt.
I don’t know if I have to select directly NOW the EFFECTIVE ORIFICE AREA of API 526 or I must do another calculation.
If I select the EFFECTIVE ORIFICE AREA of API with my ACTUAL AREA of 7.218 in2, this is letter P because in API 526 the nearest EFFECTIVE ORIFICE AREA is 6.38 in2 (P), correct?
OK, so consulting information in Internet, I have read that exists this a mathematical expression: K actual*A actual ? Kd effective (0.975) *A effective. If I do this mathematical expression with my K actual that is 0.78, I find this: A effective =(0.78*7.218 in2)/0.975= 5.775 in2.
If you go with this A effective to the API 526 you find that the nearest EFFECTIVE ORIFICE AREA is 4.34 in2 that is letter N.
As you can see, with the same initial diameter I find two different letters (P or N) and I don’t know what is the correct process. I don’t know if I have to select directly with my ACTUAL AREA an EFFECTIVE ORIFICE AREA of API 526 or on the contrary I must to transform my ACTUAL AREA to an EFFECTIVE ORIFICE AREA of API 526 with the Kd effective (0.975).
The design is ASME VIII but the center to face dimensions are according API 526, so I don't know if there is another standard that say you center to face dimensions.
Thank you for the help!
