Revamps 2024 Issue

Proposed solution

Pros

Cons

• Improved quality as rectification work

• No single point responsibility in project

 Installation of cartridge trays at

column vendor workshop by tray vendor (if required) at column vendor workshop

management

• Equipment delivery may get impacted due to involvement of two separate agencies • Coordination issues between column

with separate MRs

is easier and cost effective

• Reduced standard installation time than

on-site

• Prevents the column from deforming due to its own weight during transportation • Zero rework/repair activity on-site • Elimination of crane requirements for

vendor and tray vendor

• Transportation cost may increase • Vendors may face LD (late delivery)

charges

• Errors in matching column ID and tray OD • Challenges in procuring column through this philosophy • Transportation cost may increase • Supply cost may slightly increase because column vendor may add profit margins

installation on-site • No site hazard

• Project management through single

 Single point vendor responsibility for column and tray under same RFQ

point vendor responsibility

• Rectification work (if required) at

and installation at workshop

column vendor workshop is easier and cost effective • Reduced standard installation time on-site • Prevents the column from deforming due to its own weight during transportation • Zero errors in mismatching of column ID and tray OD on-site • Zero rework/repair activity on-site • Elimination of crane requirements for installation on-site • No site hazard

Table 1 Addressing on-site tray installations

with cartridge trays. The column designer needs to locate the intermediate and top body flanges, considering the maximum of 10-15 trays in a cartridge bundle. When finalising the column layout, the designer should also consider any internal components in the column that could obstruct the installation of cartridge trays. b) Drawing preparation: In the drawings, the tolerance required on critical dimensions, such as column ID and tray outer diameter (OD), should be indicated for columns with cartridge trays. Also, special notes should be included for precise manufacturing, flushing, and grinding inside weld joints as the cartridge tray will be installed in them. c) Use of standard pipes: Standard pipes should be used instead of plate-fabricated columns to ensure the required tolerances, which will help to install cartridge trays easily. d) Gasket size and material of construction (MOC): Other than column and tray tolerances, the MOC size and shape of gaskets play a critical role in correctly installing the cartridge bundle. Gaskets, MOC, and shape/size should be suitable to meet the compressibility/fitment requirement. e) Absolute clearance for column ID to tray OD: In cartridge trays, the tray OD = 0.98 x column ID. Due to this, the clear - ance of the tray OD with shell ID varies for different column sizes. Due to this variation, the selection of gasket size also differs from case to case, and sometimes a suitable gasket size to meet the design requirement may not be available. To overcome this, one can adopt standard absolute clearance, irrespective of column ID. f) Role of manufacturer and inspector: Correct fabrication of cartridge trays and columns plays a vital role in the proper

installation of cartridge bundles inside the column. It is often observed that columns are not manufactured within specified tolerances (mainly columns less than 500mm with a lower tolerance limit), which leads to failed installation. Hence, the manufacturer and inspector must pay careful attention to columns with cartridge-type trays to meet the specified tol - erances on column ID and verify them with Go/NoGo gauges. g) Role of site engineer and tray vendor: The site engineer ensures the column ID throughout the length and gasket compressibility before the start of installation. Designers are not normally present on-site at the time of installation, so the site engineer must ensure all requirements as per the approved drawing are met. Cartridge tray installation challenges: Impacts on HSE, time, cost, and proposed solution: Ensuring the proper installation of cartridge-type trays is a critical phase during job execution. Even minor deviations in the physical equipment from the design requirements can have significant repercussions. Loose or overly tight gaskets can hinder installation, impacting schedule, cost, and overall column or unit performance. Recent projects have shown that mismatches between columns and cartridge trays can lead to issues, especially when separately supplied and installed on-site. The data analysis revealed that mismatches led to modifications in both the column and tray and sometimes even required reordering equipment. This process, including modifications and reorders, took approximately 60 days to install single columns. An average of five such installations per year costs

Revamps 2024