MECHANICAL

LOWER TRAY INSPECTION POINT | TOWER INTERNALS

By PakTechPoint Published Updated 11 min read

In this article
  1. LOWER TRAY INSPECTION SHEET
  2. LOWER TRAY INSPECTION POINT | TOWER INTERNALS
  3. BEAM INSTALLATION
  4. PANEL INSTALLATION
  5. PANEL FASTENING
  6. ROPE PACKING
  7. PANEL SEALING
  8. LOWER PIPING MANIFOLD INSTALLATION
  9. LOWER MANIFOLD PIPING / LOWER TRAY TESTS
  10. EQUILIBRIUM DEVICE INSTALLATION
  11. BEAM INSTALLATION
  12. TRAY CLEANING & FINAL INSPECTION
  13. TRAY SIEVE LOADING
  14. TRAY SUPPORT BEAM INSTALLATION
  15. Alignment
  16. Alignment
  17. TRAY PANEL INSTALLATION
  18. TRAY PANEL FASTENING
  19. ROPE PACKING
  20. LOWER TRAY SEALING: SEAL PLATE & SEAL ANGLE PLATE WELDING
  21. LOWER PIPING MANIFOLD INSTALLATION
  22. LOWER MANIFOLD PIPING I LOWER TRAY TESTS
  23. EQUILIBRIUM DEVICE INSTALLATION
  24. FINAL INSPECTION/ BOTTOM HEAD FINAL CLOSURE
  25. NEXT TRAY SUPPORT BEAM INSTALLATION
  26. Alignment
  27. During beam installation, Axens inspector must supervise the beam
  28. In case of beam rocking, shim plates of different thickness must be
  29. Signed up on all checking points with a paint marker as following Axens marking procedure
  30. Follow the Axens sequence of installation Rocking
  31. Centering inside support ( delta
  32. max: 1 mm) and
  33. Centering between the 2 supports
  34. distance between beam angle and
  35. Alignment
  36. pipe support ring upper face
  37. support ring upper face
  38. Using as reference, on each side of the center pipe, the middle of the
  39. length between the two longest secondary beams, mark up the center
  40. pipe and the shell for further vessel dimension measurement at 700
  41. FIXED THERMOCOUPLE VERIFICATION ON BED 2, 6, 12, 14, 18, 24
  42. TRAY FINAL CLEANING
  43. Remove the section of ladder present in the bed
  44. Remove all debris and tools. Vacuum clean the neoprene
  45. Wear shoes protection before starting the tray final cleaning
  46. TRAY FINAL INSPECTION

LOWER TRAY INSPECTION SHEET

Information in this paragraph are typical points to check on site during loading. Up-to-date inspection sheets will be provided on site by start-up manager.

LOWER TRAY INSPECTION POINT | TOWER INTERNALS

  1. BEAM INSTALLATION

    1. Beam laying down on trestles at ground.
    2. Main beams installation / positioning / centering.
    3. Main beam leveling / rocking / Shim plate tack welding.
    4. Secondary beam installation / positioning / centering.
    5. Secondary beam leveling / rocking / Shim plate tack welding.
    6. Main beam — Center Pipe — Axis paint Marking.

  2. PANEL INSTALLATION

    1. Container opening / Panel laying down on outside trestles at ground.
    2. Panel punch mark checking & cleanness inspection.
    3. Panel Upper screen inspection at ground.
    4. Panel nozzle closure with plastic caps..
    5. Neoprene sheet installation on panels.
    6. Panel lifting & laving down on beams.
    7. Panel positioning with metal spacers.
    8. Panel rocking detection / Shim plate tack welding.

  3. PANEL FASTENING

    1. Tray panel bolting.

  4. ROPE PACKING

    1. Panels – Shell – Centre pipe Rope packing.
    2. Tray cleaning.

  5. PANEL SEALING

    1. Welding of Seal plates on panel frame.
    2. Welding of Seal Angles plates on welding rings of shell and center pipe.

  6. LOWER PIPING MANIFOLD INSTALLATION

    1. Storage of manifold piping inside tower through bottom manhole.
    2. Lower piping positioning / tack welding.
    3. Lower piping manifold welding / dye checking.
    4. Centre pipe connection installation.

  7. LOWER MANIFOLD PIPING / LOWER TRAY TESTS

    1. Lower manifold piping and lower tray mechanical / leak tests.

  8. EQUILIBRIUM DEVICE INSTALLATION

    1. Equilibrium device installation I inspection.

  9. BEAM INSTALLATION

    1. Beam laying down on trestles at ground.
    2. Main beams installation / positioning / centering.
    3. Main beam levelling / rocking / Shim plate tack weldinq.
    4. Secondary beam installation / positioning / centering.
    5. Secondary beam levelling / rocking / Shim plate tack welding.
    6. Main beam – Centre Pipe — Axis paint Marking.

  10. TRAY CLEANING & FINAL INSPECTION

    1. Tray final cleaning & removal of Neoprene sheets.
    2. Screen vacuum cleaning.
    3. Screen – Clip – Bellows – Beam – Cleanness inspection.
    4. Collecting data for bed volume calculation.

  11. TRAY SIEVE LOADING

    1. Loading Hopper installation / Catapac centering – positioning – testing.
    2. Sieve loading / intermediate inspection / sampling.
    3. Bed levelling / Adjusting sieve quantity / Catapac platform air blowing.

TRAY SUPPORT BEAM INSTALLATION

Procedure Hold points
– Preparation
The support beams are laid down on trestles at ground. 		Cleanness (no rust).
Number of support beams.
Main beam installation

During beam installation, Axens inspector must supervise the beam installation from inside the tower if possible.
To check level, flatness of the upper surface and alignment use spirit levels (short and long).
In case of beam rocking, shim plates of different thickness must be used and tack welded on support beam.
Signed up on all checking points with a paint marker as following Axens marking procedure

Rocking.
Centering inside support ( delta max: 1 mm).
Centering of the beam between the 2 supports (delta max: 5mm).

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Alignment

  • beam upper face with center pipe support ring upper face  (tolerance :-1; + 3 mm)
  • beam upper face with shell supporring upper face (tolerance :-l;+ 3 mm)
– Secondary beam installation

During beam installation, Axens inspector must supervise the beam installation from inside the tower if possible.
To check level and alignment use spirit levels.
In case of beam rocking, shim plates of different thickness must be used and tack welded on support beam.
Signed up on all checking points with a paint marker as following Axens marking procedure
Follow the Axens sequence of installation

Rocking
Centering inside support ( delta max: l mm) and shim plates tack welded.
Centering between the 2 supports ( delta max: 5mm with the shortest
distance between beam angle and shell).

Alignment

  • beam upper face with center  pipe support ring upper face

(tolerance:-l; +3 mm)

  • beam upper face with shell support ring upper face (tolerance :-1;+ 3 mm)
– Axis tracing

Trace main beams axis only using a ruler with a paint marker.

Using as reference, on each side of the center pipe, the middle of the length between the two longest secondary beams, mark up the center pipe and the shell for further vessel dimension measurement at 700 mm from the screen.

Axis paint marking on Main beam axis, shell & center pipe.

TRAY PANEL INSTALLATION

Procedure Hold points
– Preparation
Panels are laid down on trestles at ground. Punch mark & screen status carefully inspected.
Check the inside of the tray panels by removing the plastic cap, blow dry air or vacuum clean if necessary.
At ground, all nozzles covered with plastic cap.
Neoprene sheets taped on screen. 		Dry air in service in the adsorbers
Panel conditions at ground
Panel nozzle covers
Gasket type
– Cleanliness
During panel installation, avoid any sieve surface disturbing and ensure there is no foreign material 		Upper face of beams
Upper face of support rings
– Lower panel screen

Before positioning, each panel screen must be inspected carefully with a flash light ( damages done during handling)
– Flatness and stability of panels
Check the good contact between panels, beams and support rings.
If there is any rocking, insert and tack weld shim plate on outside edge of the frame.

Panels 1A to 8B
– Gap between panels
Install spacers for positioning and maintain the position with clamps. 		Gap between panels must be 15 mm max.
– Gap between panels and shell
Maintain a minimum gap on shell side for the rope. 		Gap between panels and shell must be IO mm min.

TRAY PANEL FASTENING

Procedure Hold points
– Clamps screwing
Install at first the screw clamps to tight the trays with the annular support ring around the center pipe and the shell
– Plate and forks joints installation
Once clamps are in position use the plate and fork joint to finalize the
tightness between trays and beams. 		Presence of fastening elements
Tightness of fastening elements

ROPE PACKING

Procedure Hold points
General remark:
Because of the toleranxces regarding roundness of the shell, the diameter of the rope to be used shall
be adjusted (30, 20, 8mm) according to the gap available especially between the panels and the shell.
The rope packing shall be done smoothly to avoid damaging the rope.
– Wire rope installation
Wire rope diameter is to be selected depending on the available gap between
shell and rope arrestor. Wire rope is used locally in order to avoid any
plugging of the bottom head vent during rope packing. 		Install wire rope around the bottom head vent nozzle.
– Rope packing general comments :
Rope packing must be done following a specific sequence given by Axens.
Use the recommended rope packing tools.
– First row
The first row must be packed carefully against the rope arrestor in order to
prevent the rope going through it.
– Rope packing
Complete the rope filling up to the top of panel frames.
– Last row of rope
Last row of rope must be flush to upper edge of panel frame. 		First row of rope wrapping & status (clean and dry) & type & diameter
No free space between panels
Gap after rope packing: 15 mm Max between panels
Last row of rope must be flush to upper edge of panel frame.
First row of rope wrapping
& status (clean and dry) &
type & diameter
No free space between
panels
Gap after rope packing: 15
mm Max between panels
Last row of rope must be
flush to upper edge of panel
frame. 		Cleanness
Remaining Rope wrapping status

LOWER TRAY SEALING: SEAL PLATE & SEAL ANGLE PLATE WELDING

Procedure Hold points
– Seal cover plate welding on panel frame
Follow typical sequence of tack-welding: tackweld point pitch= 150 mm Then continuous welding to tight the tray 		Dye test
– Seal angle plate welding on center pipe and shell welding ring
Follow typical sequence of tack-welding: tackweld point pitch= 150 mm Then continuous welding to tight the tray 		Dye test

LOWER PIPING MANIFOLD INSTALLATION

Procedure Hold points
– Preparation
Identify pipes to be assembled and pipes to be fitted before mounting. Remove all nozzle covers.
Inspect lower manifold piping at ground. Store all big pieces of piping manifold inside the tower on bottom head.		 Piping condition ( cleanliness, rust
free, dry).
Dye check
Welding quality
– Center pipe connection Gasket type
Bolting tightness
– Tray Cleaning/ scaffolding dismounting
Remove scaffolding, vacuum clean all tray surface 		Cleanliness

LOWER MANIFOLD PIPING I LOWER TRAY TESTS

Procedure Hold points
– Lower tray/ manifold piping mechanical / leak test
Follow AXENS’s procedure

EQUILIBRIUM DEVICE INSTALLATION

Procedure Hold points
– Preparation
Clear out all tray surface and vacuum clean all dust on shell. Clean,
brush rust if any on the flange.		 Piping condition ( cleanness, rust
free, dry
Flange cleanness
– Equilibrium device installation / bolting Gasket type
Gasket positioning
Bolting tightness
Bolting on lugs
-Bottom head flush inlet connection (2 in. ) Piping assembly after tack welding.
Dye check
Welding quality
Gasket type
Gasket positioning
Bolting tightness
-Sampling connection (3/4 in.) Piping assembly after tack welding.
Dye check
Welding quality

FINAL INSPECTION/ BOTTOM HEAD FINAL CLOSURE

Procedure Hold points
– Final inspection Cleanliness
Gaskets installation
– Bottom head manhole closure Gasket position, type
Tightness of bolting
– Pumparound nozzle closure Temporary Gasket installation

NEXT TRAY SUPPORT BEAM INSTALLATION

Procedure Hold points
– Preparation
The support beams are laid down on trestles at ground. 		Cleanness (no rust)
Number of support beams
Main beam installation
During beam installation, Axens inspector must supervise the
beam installation from inside the tower if possible.
To check level, flatness of the upper surface and alignment use
spirit levels (short and long).
In case of beam rocking, shim plates of different thickness must be
used and tack welded on support beam.
Signed up on all checking points with a paint marker as
following Axens marking procedure 		Rocking
Centering inside support ( delta max: 1 mm)
Centering of the beam between the 2
supports ( delta max: 5mm )

Alignment

  • beam upper face with center pipe support ring upper face (tolerance :-1; + 3 mm)
  • beam upper face with shell support ring upper face (tolerance:-1; +3 mm)
– Secondary beam installation

During beam installation, Axens inspector must supervise the beam

installation from inside the tower if possible.

To check level and alignment use spirit levels.

In case of beam rocking, shim plates of different thickness must be

used and tack welded on support beam.

Signed up on all checking points with a paint marker as following Axens marking procedure

Follow the Axens sequence of installation Rocking

Centering inside support ( delta

max: 1 mm) and

shim plates tack welded.

Centering between the 2 supports

(delta max: 5mm with the shortest

distance between beam angle and

shell).

Alignment

  • beam upper face with center

pipe support ring upper face

(tolerance :-1; +3 mm)

  • beam upper face with shell

support ring upper face

(tolerance: -1; +3 mm)
– Axis tracing

Trace main beams axis only using a ruler with a paint marker.

Using as reference, on each side of the center pipe, the middle of the

length between the two longest secondary beams, mark up the center

pipe and the shell for further vessel dimension measurement at 700

mm from the screen.

Axis paint marking on Main beam axis, shell & center pipe.

FIXED THERMOCOUPLE VERIFICATION ON BED 2, 6, 12, 14, 18, 24

Procedure Hold points
Check any damage on the thermowell

Pack some rope in the nozzle to minimize dead volume

Status of the thermowell

Rope packing in the nozzle

TRAY FINAL CLEANING

Procedure Hold points
– Preparation

Remove the section of ladder present in the bed

Remove all debris and tools. Vacuum clean the neoprene

sheets before removal.

Remove all neoprene sheets and vacuum clean the screen.

Wear shoes protection before starting the tray final cleaning

to avoid damaging the screen

Shoes protection to be worn all the time

Bed free of ladder

TRAY FINAL INSPECTION

Items for inspection : Laser meter, ruler (3m), pen, wrench XX, spirit levels (short & long), flash light, Axens tray doc., small knife

Procedure Hold points
– Adsorber conditions
Dry air must be blown to ensure a dry atmosphere before sieve
loading		 Dry air in service
Access to bed during loading
– Ladder Bed free of ladder
– Screen status & slot spacing Slot spacing checking with feeler gauge
– Rope packing Rope packed everywhere
– Seal plates Position
Welding
– Beam conditions
Walk on it to detect any rocking 		Rocking
Level
Axis marking (beam axis)
– bottom head piping
Look for any uncompleted work, absence of gasket… (and presence
of the additionnal piping needed as V3 complement) 		Bolting ( checked with a wrench)
Gasket type
– Cleanness
Look for remaining tools, dye stains, welding stains. In case of dust or dirt, ask for more cleaning (vacuum cleaner). 		Shell / center pipe
Upper part of beams
Support Ring on center-pipe / shell
Screen surface
– Thermocouple Position
– Collect data for volume calculation Bed diameter measurement
Height measurement

BEFORE LEAVING THE BED CHECK THAT ALL TOOLS USED FOR INSPECTION HA VE BEEN COLLECTED

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