API 650 Tanks - Flush type connection

[vermatron]

A few doubts regarding API650 Flush type connections.

1) Is it possible to Design a Flush type opening such that the "nozzle centreline" is in flush with the bottom plate ?
2) It is known that heat treatment is required for flush type connections. If a cleanout opening is designed for the tank without an insert plate, ie, the opening is attached to the shell directly then, can heat treatment be applied to the region near the flush type opening OR should the whole shell course be heat treated ?
3) Is it necessary to perform FEA analysis on the flush type opening ?
4) The minimum value of height of the opening from Table 5.12(a)[API 650 12th Edition] is 200 mm. I want a Flush type opening nozzle of 6"Sch80S(ID = 146mm). Is it possible ?

 

[IFRs]

1) You can do anything to a tank including what you describe but only the things in API 650 will be "to the standard". If you deviate from the standard you manage the increased risk using good engineering judgment.

2) According to the standard, the plate that contains the flush type nozzle should be included in the PWHT.

3) Not if you are using the details in the standard.

4) Yes, but it will not be "to the standard" and there will be increased risk.

My opinions only!

 

[vermatron]

Thanks a lot IFRs for your opinions.
A few more clarifications.

4) So shall I design the opening with 200mm, and then use a reducing transition to fit with the 6" nozzle ? What's your opinion ?

 

[IFRs]

API 650 is silent on what you do after the first flange. You can certainly put an 8 x 6 reducer ( eccentric flat on bottom? ) after the flush nozzle.