Packing Support Grid RFQs: What Information Determines the Support Design?

A support grid is sometimes quoted as though it were simply:

SS316L support grid, diameter 2000 mm.

Diameter and material are important.

They do not define the required structure.

The supplier also needs to know what load the grid supports and how it interfaces with the vessel.

Packing Type

The supplier should know whether the grid supports:

metal random packing, plastic random packing, ceramic packing, or structured packing.

Their weights and load characteristics differ significantly.

Bed Height

Packing type without bed height does not define the total supported load.

The RFQ should therefore state the height of packing above the grid.

Bulk Density

If known, the design bulk density should be provided.

If the supplier provides the packing as well, it may use its approved packing data.

For third-party packing, the buyer should supply the relevant value.

Liquid Load and Other Design Loads

Depending on project requirements, the support may need to account for:

liquid holdup, fouling, maintenance load, or upset conditions.

The structural design basis should be agreed rather than guessed.

Tower Interface

The supplier needs information about:

support ring, beams, clips, bearing width, and elevation.

Without this interface data, it cannot finalize how the grid is supported.

Required Open Area

Hydraulic open area should be included where process design sets a minimum requirement.

The structural design should meet the load without unnecessarily restricting flow.

Packing Retention

The supplier should know the smallest packing dimension so that openings do not allow packing to fall through.

Manway

Large support grids normally require segmentation.

The clear access opening should be supplied at RFQ stage.

Structural Responsibility

The quotation should make clear whether the supplier is responsible for:

fabrication only or structural design and verification.

If calculations are required, state this before commercial evaluation.

Engineering Takeaway

A support grid price based only on diameter and alloy may not represent a complete engineered support.

Packing load, open area, vessel interface, segmentation, and calculation scope should be fixed before the order becomes fabrication-ready.