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Reconditioning of a flue gas double disc slide valve Ø48

PhotoReport
Valve body [view a full-size image] 62Kb Jpg file
Crack repair [view a full-size image] 44Kb Jpg file
Bonnet [view a full-size image] 56Kb Jpg file

THE PROBLEM: This valve - originally not manufactured by REMOSA - regulated the pressure coming out of a FCC unit regenerator at the AGIP refinery at Sannazzaro de' Burgondi, Italy. It showed many cracks in the welded zones, caused by a serious thickness difference between body and bonnet. A complete reconditioning of the valve was necessary to avoid a longer plant stoppage, while planning for a new valve to be built.

Dye penetrant inspection on the valve body: cracks on bonnet and bonnet flange.

TECHNICAL DATA:

• Construction Date: 1985
• Body: SA 240 - Tp304H
• Disc: SA 240 - Tp304H
• Guides: SA 240 - Tp304H
• Stem: SA 182 - F304H
• Lip Seal: SA 240 - Tp304H
• Refractory Materials: RESCO AA 22
• Hex Mesh: 19 - 14 - 6A - 304H
• Total Weight: 8360 kg
• Body Weight: 5560 kg
  
  Design conditions
  • Pressure: 2.75 bar
  • Temperature: 788 ^oC
  • Stroke: 406 mm

SOLUTION: Remosa intervention included the following tasks:

1. valve and actuator disassembling
2. substitution of the old lip seals
3. substitution of the resistant lining RESCO
4. hex mesh restoration
5. operation controls with penetrating liquids
6. UT welding controls
7. weldings rebuilding
8. dimensional checks
9. restoration of fixing threaded holes
10. restoration of all flanges
11. dimensional check of the new trim
12. sandblasting of all valve parts

REMOSA worked together with I.I.S. (Istituto Italiano della Saldatura, Italian Welding Institute), which took care of the metallographic analysis for the valve structure.

The reconditioned valve was able to take service as good as a new one, and the plant was running again in less than one month.

Copyright © REMOSA spa 1998-2001 Last updated on May 5, 1999