Revamps 2025 Issue

Probable causes of on-site failures

Problem category

Probable causes

1. Design

• Wrong tolerances selection • Improper sealing gasket material and thickness • Less design experience in executing similar projects

2. Fabrication

• Out of tolerance in column inner diameter (ID) • Difficulty in achieving correct ID of column throughout the column length • Intermediate weld joints not properly ground flushed • Fabricated tray bundle outer diameter (OD) is not as per fabricated column ID • Not following standard guidelines for inspection • Quality of gasket material not properly inspected • Limited experience in inspection activities for similar projects • Improper handling of columns during transportation • Damage to the column due to poor road conditions at some places • Improper storage of column and trays at site • Ovality in column due to self weight during transportation

3. Inspection

4. Logistics

5. Installation

• Tolerances mismatch between tray and column OD/ID • Sealing gasket is not compressing properly • Delay in tray bundle installation activity • Improper erection of column

Table 1

Site cartridge tray installation problem and HSE risks Installing cartridge trays presents its own set of challenges. Typically, cranes with long booms are used to lift the car- tridge tray bundles to considerable heights above the col- umn flanges. The complexity increases significantly when either the column or the tray bundles are fabricated outside their specified tolerance limits, resulting in oversized or undersized trays relative to the column shell. If a tray bun - dle becomes stuck during insertion due to these discrepan- cies, in-situ modifications to either the column shell or the tray assembly become necessary. Such modifications turn an already high-risk opera - tion into a laborious and hazardous task. The installation team may often be required to enter the erected column by being lowered with a crane (or similar means), to man- ually remove excess material (typically unground welding beads that remained post-shop fabrication). This operation exposes personnel to toxic fumes and fine metallic dust in a confined space, posing serious health risks. Additionally, working at elevated heights under these conditions further compounds the safety hazards. The efficiency of distillation columns heavily depends on the proper functioning of their internals. Improper installa- tion of these internals can lead to severe and immediate consequences, such as reduced product quality, unsched- uled shutdowns, and operational disruptions. Hence, metic- ulous inspection of the internals, aligned with approved drawings and design specifications, is critical. Specialist inspections and prompt resolution of any identified punch points are essential to ensure optimal column functionality. This proactive approach not only prevents potential issues but also minimises the need for costly and time-consuming

Figure 2 Cartridge tray bundle

Revamps 2025