250.520—When do I have to perform a casing diagnostic test?
        
        (a) 
         You must perform a casing diagnostic test within 30 days after first observing or imposing casing pressure according to the following table:
    
    | If you have a * * * | you must perform a casing diagnostic test if * * * | 
|---|---|
| (1) fixed platform well, | the casing pressure is greater than 100 psig. | 
| (2) subsea well, | the measurable casing pressure is greater than the external hydrostatic pressure plus 100 psig measured at the subsea wellhead. | 
| (3) hybrid well, | a riser or the production casing pressure is greater than 100 psig measured at the surface. | 
        
        (b) 
         You are exempt from performing a diagnostic pressure test for the production casing on a well operating under active gas lift.