Troubleshooting Process (part 1)
There are three main parts involved in the process of troubleshooting
mechanical seal failures. These three parts correspond to steps
1.through 4.in problem solving. Steps 5.through 7.in the problem
solving process will require experience, data evaluation, and
retained knowledge to apply them towards mechanical seal troubleshooting.
The three main parts of seal troubleshooting are listed below:
- Gathering all of the
ACCURATE APPLICATION DATA available
- Gathering all of the
SYSTEM INFORMATION available
- Making notations of the
PHYSICAL EVIDENCE as you are inspecting
each individual seal component during disassembly
The key to quick, accurate, and effective seal failure analysis
is to be able to inspect the physical evidence (seal and
rotating equipment) and relate the physical evidence to
and/or system data. It is very important that all three parts
of the information be available in order to make the proper
recommendation to solve the problem.
There is no better place to perform a failure analysis than
at the site the failure took place. The physical evidence and
the application and system operation data is fresh in everybodyÕs
mind. Troubleshooting mechanical seal failures is not a simple
process, but with experience, product knowledge, and confidence
you can be providing solutions to your customer and improving
product reliability, thereby reducing plant downtime.
Be aware that there are often factors other than the mechanical
seal that contribute to premature seal failure.
Some of the other factors that should be considered are:
- FLUID CHARACTERISTICS
- EQUIPMENT CONDITIONS
- SYSTEM OPERATION
- SYSTEM/EQUIPMENT DESIGN
- ENVIRONMENTAL CONTROLS
- MAINTENANCE PRACTICES 4
Listed below are common factors that contribute to early seal
failure along with some helpful questions that will improve
your troubleshooting skills.
- Does it crystallize?
- Does it coke?
- Does it harden or setup?
- What is the % concentration?
- Is it a lubricating or non-lubricating fluid?
- Measure the radial and axial movement.
- What is the condition of the bearings?
- Are there alignment problems?
- Is the impeller balanced and positioned properly?
- Does the system run dry?
- Is thermal shock an issue for the seal?
- What are the system cleaning procedures?
- Is it a cycling process?
- Is there water hammer?
- Is cavitation a problem?
- Where is the pump operating on the curve?
- What is the shaft L/D ratio?
- What is the valve/piping arrangement?
- Have there been any piping changes?
- Are filters or strainers being used?
- What is the flush pressure?
- Is it reliable?
- Do you need a dual seal?
- Do you need to consider a steam quench?
- Is there a cooling jacket?
- What are the seal installation practices?
- Do the maintenance personnel require product training?
- Is the pump repaired when the seal is installed?