Leaking during Hydrotest for Floating Shell & Tube Heat Exchangers (AFS)

[yespii]

Hi All,

Really need your insights on the problem i'm currently facing for shell and tube heat exchangers.
This is AFS type HX, which having floating tubesheet complete with floating head.
Problem is during Hydrotest, leaking start to occur at this floating tubesheet to floating head joint.
It's only a water drop but consistently happening. tter.
Gasket used for this joint is Kammprofile SS316L. Tubesheet and flange head is Duplex.
We have tried to change the gasket to spiral wound SS316L but the issue resists.
Bolt tightening and torquing has been done according to torque value and in properly sequence.

This unit HT pressure is 65 bar.
Leaking start during building up pressure from 56 bar.

Anyone of you ever experience the similar as above?
I appreciate your advise please.

 

[TGS4]

How were your bolt loads determined?. Obviously they're inadequate, and changing the gasket likely invalidated the calculations.

 

[TiCl4]

1. How are you determining the torque value of the bolt?
2. What was initially specified when determining the required torque value to achieve the necessary bolt load? Are you sure you are using the EXACT same bolts/thread locker/etc that was specified/assumed in the bolt loading calculations? A change in any of those will change the required torque to achieve the necessary bolt loading.
3. Changing your gasket type has messed the bolt loading calculations up.

Also, I've heard that even at the same exact torque with "identical" bolts, bolt loading can have a decent scatter on results. I have no personal experience or data. Perhaps someone more familiar with the bolt loading calcs and live results can chime in.