Refractory Failure Analysis
There are a great number of issues that can lead to a refractory failure. Some of these failures are very common to similar industries, types of systems and equipment and others are quite unique. Gold Coast Refractory Service has associates that have extensive experience performing refractory failure analysis in the many different conditions and scenarios that can occur around refractory failures.
Finding the root causes of a refractory failure can be a complicated matter involving issues such as:
- Improper storage, mixing, installation of refractory materials.
- Material not properly suited for the application.
In all cases, the first phase of refractory failure analysis begins with collecting all available information on the system’s equipment, material selection and storage, plant operations, other chemicals and fuels used and installation, and drying procedures.
During the first phase of refractory failure analysis, the following information should be discovered and detailed documentation of the data should be created:
- Material samples and data sheets of the existing brick or refractory lining, ash clinkers and slag
- Chemical analysis of the fuel
- Storage location and duration prior to installation
- Manufacture date and quantity installed of the refractory material
- Ambient condition at the time of the installation
- Installation or application method (pneumatically, poured, toweled, shotcrete, etc.)
- Material curing or drying methods, and procedures that were used
The second phase of any refractory failure analysis should include an examination of the existing refractory material, or lack of refractory material, for symptoms of the root cause of the failure. When reviewing this existing lining or images of the existing lining, the following should be considered:
- Material exposure to extreme temperatures (excessive shrinkage, glazing, etc.)?
- Equipment, furnace or boiler failure due to operator error?
- Improper installation of refractory material (i.e., porous or popcorn-like texture)?
- Material failure due to thermal shock (large sections of the top surface area sheared away)?
- Indications of mechanical abuse (broken and jagged edges or holes)?
When materials are gathered for testing, they should be sent out for a cold crush test which verifies the strength of the installed material. The results of the cold crush test can be matched to the manufacturer’s material data sheets. If it appears that the strength of the installed material is too low, it is likely that the mix was too wet when installed.
Chemical analysis should be conducted on samples of the existing slag and ash clinkers. In addition, a pyrometric cone equivalent (PCE) test should be performed on the slag samples to confirm the minimum temperature to which the refractory material was exposed. This type of documentation of the environment to which the refractory material was exposed is the third phase of refractory failure analysis.
Another way to do this is to calculate the base-to-acid ratio (b/a), using values taken from the data received from the completed chemical analysis testing. This b/a value will give an idea as to what type of refractory material should have been selected.
In the fourth phase of refractory failure analysis, all collected data is examined. Service conditions must be studied carefully in order to see any impact on the installed/failed material. This includes the raw materials or fuel being burned, used startup fuel, ash and slag composition, gas temperatures, and plant operations.
The final fifth phase is an analysis of proper installation procedures. All of the items listed below could stop a refractory material from reaching its correct strength and must be evaluated. A refractory material that cannot reach its designed strength for any reason has the highest chance of failure.
- Manufacture Date and Storage
- Quantities
- Correct Installation
- Mixing Water
- Equipment and Pot Life
- Ambient Conditions
- Curing Procedures
- Drying Procedures
We, at Gold Coast Refractory Service, have experience and expertise around conducting these investigations, and can help you get to the bottom of any refractory failure you may experience.
