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[MW:6850] Tank Nozzle Thickness

By Materials & Welding
Dear Members,
 
1. we have a slop tank which has been designed as per API 620 but the contractor has not specified the original thickness of the 24" nozzles in the general arrangement drawing and instead it has been mentioned as per code. Now when we have carried out the thickness measurment of nozzles we need to know the original thickness in order to access the extent of thickness reduction. we want to know how to calculate the original thickness of nozzles.
2. we have one diesel tank which has been designed as per API 650, during the thickness measurement we have observed the thickness for a 20" nozzle as 4.8 mm instead of oiginal 6mm with an corrosion allowance of 1 mm. But in API 650 table 3.4 it has been given that the minimum neck thickness for 20" nozzle should be 6mm. Can this thickness of 4.8 can be accepted.
 
Please provide your comments. Thanking you in advance.
 
Regards,   

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