Dear all,

I have query regarding jacketed vessel hydro test.
Equipment type – Heat exchanger – Tema type BKM –550-1050X9753 mm

Jacked ID = Channel ID +100 mm

Front & rear channel are steam jacketed to maintain liquid sulphur temperature

Design Conditions –

Code – ASME sec.VIII Div-1 2010 edition + API 660 8th Edition + TEMA class-R 9th edition

Vessel side Design Conditions
Design Pressure (Int. /Ext.) bars G 14.2 / FV
Design Temperature (Int./Ext.)Deg. C 178 / 190
Provided thickness-mm 13
Material SA-516-60
Corrosion allowance 3.2

Jacket side design conditions
Design Pressure (Int. /Ext.) bars G 5.6 bars G / FV
Design Temperature (Int./Ext.)Deg. C 178 / 190
Provided thickness-mm 10
Material SA-516-60
Corrosion allowance 3.2


I have design inner vessel vessel with internal pressure as 15.25 bars & external pressure as 6.65 bar pressure.
Client specifications calls for shop hydro test shall be as per UG-99(C) & shall not be limited by the nozzle reinforcement.

Query – 1

Dear Modearator

As we all know that type-2 jacket is only analysed in codecalc not in pv-elite.

But codecalc doesn't ask for the input for the jacket side external pressure.

This will underdesign inner vessel.In my case codecalc only considers 14.2 bar inplace of 14.2+1.05(full vaccum on jacket side) = 15.25

Kindly add this input in your next patch / version in pv-elite & codecalc.

Query – 2

During hydro test of jacket side which MAP shall be taken.

Shall we consider inner vessel walls as a part of jacket & accordingly find governing MAP for the jacket? (This will be MAP for jacket elements & MAEP for Inner vessel’s elements)

If I only consider MAP of jacket shell & head hydro test pressure = 1.3*29.132=37.816 bar

This will be higher than MAEP (maximum allowable external pressure) of inner vessel’s elements.

At this pressure inner vessel is failing we need to increase thickness of inner vessel.
Supplier is considering MAEP of inner vessel’s head as governing MAWP = 7.2 bar & designed nozzles for this MAWP.

MAP is limited by nozzle reinforcement = 8.15 bar
Accordingly hydro test pressure = 1.3*8.15=10.53 bar

Is this acceptable? Supplier is doing hydro test of jacket as per UG-99(b) is this correct?

Query – 3

If I need to hydro test as per UG-99(C) I need to find MAEP of inner vessel in new & cold condition.

Hydro test pressure = 1.3*MAEP (new & cold condition) than inner vessel will not be able to withstand this pressure. Any way we need to increase thickness.

Because likewise in case of internal hydro test pressure we can take advantage of 90% yield but
In this case due to external hydro 90% yield will not work out.

Than what to do shall we limit hydro test pressure?

Please advice.
Share your views.