Our vessel have two internal long nozzles for future use. Internal nozzle have 2 weld joints and flange. These nozzle through vessel shell and continuous by external nozzles. During hydrostatic test, external nozzles are closed by blind flanges and internal nozzles are opened.
Question:
- Are the long internal nozzles has been hydrotested by above scheme?
- Which is section of ASME VIII relate to internal nozzle?

Please help, thank you,

there is no need to consider Hydrostatic test for internal nozzle, the reason is that the internal nozzle subject to both internal and external pressure with same value at same time.

Fred Wang,

This is not always true that internal nozzles pipe are subject to same internal and external pressure. Let us assume, there is an internal nozzle at the top of vertical vessel whose height is 2500 mm (tangent o tanget distance). The highest operating level is 1500 mm, so the interal projection of the nozzle pipe is within the free space. There is no pressure outside the nozzle pipe in this case.

Whatever the case is, just perform hydrostatic test in a usual way that will serve the purpose and Code requirements as you already pointed out.

The above is just my opinion.

_________________
Thanks & Regards,
Nasir
Welding Engineer
DESCON Engineering Limited.
Lahore, Pakistan.
Mobile # 0092-336-4145402

Internal dip pipe not below the liquid level does not mean that there is no pressure outside, it is still experiencing pressure within the equipment.
If it is below the liquid level, an extra pressure equivalent to liquid head will be applicable.

Hi Sanjeev,

I am still confused how the pipe experiences external pressure from the tank when not dipped into the fluid?

_________________
Thanks & Regards,
Nasir
Welding Engineer
DESCON Engineering Limited.
Lahore, Pakistan.
Mobile # 0092-336-4145402

Nasir,

Any element inside the pressure vessel will experience the pressure at which equipment is operating but its a situation of pressure equalization as the pressure is acting on all the faces of that element.

It has nothing to do with vapor space or liquid section within the vessel.