Pre-heater Flange Clamp

Client: Tengizchevroil

Problem Summary


Anomaly Description:
A small leak was detected on the body flange of vessel 1E-405.2. The gasket and studs are over 20 years old. The existing studs were corroded and could not be re-tightened. The existing sheet gasket is completely confined and can withstand a higher compression gasket load.
The client had completed a bolt change out of procedure, yet the leak of H2S was still present.

Root causes:
The gasket and studs that have been in service for 20 years had not been replaced and as a result were deteriorated.

Integrity concerns:
Further degradation of gasket and bolting would lead to increased exposure of H2S into the environment. H2S exposure to human health is hazardous with large amounts of exposure being fatal. There was also the risk of Stress Corrosion Cracking with the bolting being exposed to sour service.

Technical Details

Line Size:
Design Pressure:
Operating Pressure:
Design Temperature:
Operating Temperature:
Line Class:
3410 x 320mm
0.48 BAR
ASTM A350 LF2 CL.1

The Beruseal Solution


Clamp Design:
Beruseal designed and manufactured an 8-Part flange insert-lip-clamp that would be clamped around the vessel flange. Due to the sheer size of the ring clamp, the design underwent an FEA analysis to accurately determine the stresses that the clamp would be exposed to.

As the clamp design had a seating area on top of the vessel flange, precise measurements had to be made to ensure the clamp sits flush on the 3400mm vessel flange and is able to create an effective seal. The enclosure was also CNC machined from the 3D model to ensure the dimensions were accurate exactly as per the design.

A PTFE based sealant was injected into the cavity of the flanges. High precision measuring and machining was taken and a successful seal was obtained.


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