Corrosion, Failure Analysis and Materials Selection Specialists

 

 

 

 

 

Corrosion Testing / Failure Analysis

 

 

 

Corrosion Testing

Failure Analysis

Field Investigations

Litigation

Metallography

Technical Papers

CTL Profile

Pricing & Policies

Contact CTL

Quality Assurance

Return to Failure Analysis Case Histories

Dezincification of Brass Heat Exchanger

ENVIRONMENT:

Slightly Alkaline Water

EQUIPMENT:

Heat Exchanger
MATERIAL: Brass

FAILURE:

Plug Type Dezincification

 

This heat exchanger experienced failure due to cracking of the heat exchanger tubes. A dark red/black deposit covering the ID contained several locations with cracks or pits (Figure 1).

A cross section was made of a typical pitted area. The ID pits were filled with a deposit and contained cracks growing from the bottom of the pit (Figure 2). This cross section was examined using energy dispersive x-ray analysis (EDS). EDS clearly showed that the pits were the result of dezincification.

Conditions favoring dezincification are: contact with slightly acid or alkaline water, not highly aerated, low rates of flow of the circulating liquid, relatively high tube-wall temperatures, and permeable deposits or coatings over the tube surface.

 
Figure 1. Crack on the ID of the copper tube Figure 2. Dezincification plug (100X Original Magnification)

Site Index

Site Copyright 1995 - 2007, All Rights Reserved,

Corrosion Testing Laboratories, Inc.

60 Blue Hen Drive

Newark, Delaware USA 19713

Phone: 1-302-454-8200

Fax: 1-302-454-8204

web@corrosionlab.com