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Maintenance
Shell and tube HEX bundle offline spare criteria and storage procedure
This article details the guidelines to identify and establish spare criteria for critical assets ( Shell and tube heat exchangers tube bundles categorized as “ High Risk ”) in order to allow increasing the asset availability and minimize the equipment downtime due to lengthy and costly repairs .
By Miguel Gutierrez , Field Consultant Engineer at GME – Reliability Solutions Department in Saudi Aramco
Objective The main drivers to establish the required guidelines for maintaining a heat exchanger tube bundle spare ( Offline asset sparing philosophy ) are given by the asset criticality classification ( Only applicable for “ High Risk ”), operational requirements , asset interchangeability , failure modes and frequency , lead time for tubes fabrication , logistics and space constraints , cost considerations ( Cost of spare bundles and inventory holding costs ) and repair vs replacement decision . The benefits of implementing an offline bundle sparing philosophy focus on ensuring a reliable plant operation and efficiency which will translate on enhancing plant performance , reduce overall maintenance costs and extend bundle service life .
Expected benefits
• Minimal operational downtime : Ensure critical process has minimal disruption by having spare tube bundles readily available for immediate replacement when failures occur .
• Improved maintenance efficiency : Streamline maintenance activities by cataloging tube materials and having spare bundles available . This allows for unplanned or planned maintenance to be carried out quickly and efficiently without depending on tubes manufacturer delivery or bundle replacement .
• Enhanced equipment reliability : Increase reliability by identifying common failure modes , avoiding prolonged operations under sub-optimal conditions that could lead to a large failure .
• Avoiding costly delays : Production losses and penalties due to long repair lead times ( Extended MTTR ) can be avoided by maintaining a spare parts inventory .
• Reduced unplanned shutdowns : Prevent unplanned shutdowns that can be costly in terms of production losses and associated penalties by ensuring spare tube bundles are readily available in case of unexpected failures .
• Optimized spare parts inventory : Develop an efficient offline asset sparing strategy by holding critical spare bundles without over-
Establish a spare tube bundle criteria ( Offline Asset Sparing Philosophy ) |
Is the tube bundle interchangeable with other similar equipment ?
NO
|
YES |
YES |
Is fabricatin maintaining bundle more cost than pre-ordering retubing a ex especially d
TA cycle
Y
|
Historically , has any particular tube bundle experienced severe fouling / scaling that makes tubes cleaning difficult , costly and time consuming ? |
YES |
In case retubing is necessary , Does the bundle MTTR historically exceed the maximum acceptable time per best industry practices ? |
Fabricate a spare have it available in th preserved in a nitro
Use / install spar whenever is n
|
NO |
|
NO |
|
Pre-order tubes and proceed with retubing during TA . Reevaluate criteria for spare bundle requirement or procure a new tube bundle in advance in case of alloy tubes
* Replacing the tube bundle ( use spare bundle or procure a new bundle ) instead of retubing is more cost effective , especially in those cases where the bundle repair / retub
Shell and tube heat exchanger tube bundle spare criteria for high risk bundles ( offline asset sparing philosophy ) flowchart .
20 Heat Exchanger World March 2025 www . heat-exchanger-world . com