Heat Exchanger Tube Failure - Materials Processing Institute · Section of heat exchanger with...

Address: Materials Processing InstituteEston RoadMiddlesbroughTS6 6USUnited Kingdom

Contact Details: t: +44 (0)1642 382000enquiries@mpiuk.comwww.mpiuk.com

Copyright © Materials Processing Institute UK CS/002/ME/2015

THE PROJECTThe Institute was requested to carry out aninvestigation into a recurring problem withwater leaks on a heat exchanger associatedwith the steel production process route. Therequest was to identify the root cause of theproblem and to suggest remedial action.

The heat exchanger was designed for anoperational life of 15 months, but due toincreasing numbers of leaks it was taken outof service after 12 months. Reduced lifespanof the heat exchangers was noted onsuccessive occasions. Water leaks led todowntime for weld repairs and excessivewater leakage at this location was a safetyconcern.

On-site inspections were carried out followedby sampling. From optical and electronmicroscopy analysis it was found that thewhole of the heat exchanger tube work wassuffering from severe cracking.

THE OUTCOMEIt was determined that the leaks wereoccurring by corrosion fatigue cracking. The mechanism was symptomatic of theplant operating method and necessitateda redesign to give future viability to theoperations. This was done and in the threeyears of operation water leaks have notbeen a problem.

Section of heat exchanger with multiple weld repairs on some tubes

Sample of tube with surface cracks plus cross sectional microstructure

Heat Exchanger Tube Failure

Outer Face(Hot Face)

Outer Face (Hot Face)

Inner Face(Water Side)

Tube Wall

Out

er F

ace

(Hot

Fac

e)

CASE STUDY