How to Troubleshoot & Resolve NDT Cleaning Problems

How to Troubleshoot & Resolve NDT Cleaning Problems

5 basic steps to identify and solve a NDT aqueous cleaning issue, and a troubleshooting guide with common problems and solutions

By David Geis, Product Manager

Cleaning parts using aqueous solutions are usually only one part of a much larger manufacturing process. When a problem arises in the process, technicians and engineers need to trace the source of the problem and determine the best solution.

Sometimes a problem will appear immediately after the step causing it. In those cases, troubleshooting can be simple and straightforward.

Other times, problems will only appear after several more processing steps. In these cases, tracing back the root causes can be difficult.

In this article, we outline 5 basic steps you can take to identify and resolve an issue with your aqueous cleaning system, and give you a list of common problems associated with water-based cleaners along with solutions for each.

5 Steps to Resolve an Aqueous NDT Cleaner Problem

Identify: Identify the stage in the process where the problem first becomes apparent. Closely observe that stage to find out what makes the problem visible.
Find the source: Starting with the identified stage where the problem becomes apparent, work backwards through the process and closely observe each stage to identify the source of the problem.
Monitor: When the stage causing the problem is found, monitor that stage to find out if the problem is transient, if it is periodic or if it is inherent to the process.
Dig deeper:
1. If the problem is transient or temporary, identify whether any materials or conditions have changed. Sometimes a simple change in material can introduce unforeseen problems.
2. If the problem is periodic or sporadic, observe the environment and nearby process stages. Sometimes seemingly unrelated operations can influence each other to create a problem.
3. If the problem appears to be inherent in the process stage, collect as much information as possible. Evaluate whether the problem can be eliminated by changing the stage where the problem originates, or by changing the stage where the problem becomes apparent. Determine whether subsequent process stages would be affected.
Take action: Based on the information you have, implement the best solution to the problem.

Common Problems with Aqueous Cleaning

If you have concerns or troubles with your process that are not covered in this list, please contact us so our experts can help you find the right solution to your cleaning issues.

Part is not clean (general)

Possible Causes	Solutions
Cleaner concentration is too low	Check cleaner concentration and adjust if necessary.
Temperature is too low	Check temperature controller and adjust if necessary.
Parts are not cleaned for long enough	Increase the time that the part is processed.
Cleaning solution is loaded with too much soil	Check soil levels. If necessary, dump cleaning solution and clean out reservoir to remove soil sediment. Refill with fresh cleaning solution.
Parts are not rinsed enough	Increase rinsing time. Increase flow of rinse water. Check rinse water for contamination.
Cleaner solution is not aggressive enough	Switch to a higher pH, higher alkalinity cleaner.

Part is not clean (hand scrubbing)

Possible Causes	Solutions
Parts are not scrubbed enough	Increase scrubbing action on part

Part is not clean (soak tank, agitated tank, ultrasonic tank)

Possible Causes	Solutions
Dirt is not being lifted off surface because ultrasonic power is too low	Adjust ultrasonic power setting
Large particles not removed because ultrasonic frequency is too high	Adjust ultrasonic frequency setting
Small particles not removed because ultrasonic frequency is too low	Adjust ultrasonic frequency setting
Too many parts loaded in bath at one time	Decrease number of parts processed at one time

Part is not clean (spray washing)

Possible Causes	Solutions
Too many parts being processed at one time	Decrease number of parts processed at one time to allow more space
Parts are arranged so that spray is inconsistent	Rearrange parts in basket

Part surfaces are dark after cleaning

Possible Causes	Solutions
Cleaner concentration is too high	Check bath concentration and dilute if necessary
Bath temperature is too high	Check bath temperature controller and adjust if necessary
Metal surface is being attacked by aggressive chemistry	Switch to lower pH, l ower alkalinity cleaner solution
	Switch to a solution with more corrosion inhibitors

Parts have a rainbow pattern similar to heat burn

Possible Causes	Solutions
Bath temperature is too high	Check bath temperature controller and adjust if necessary
Dryer temperature is too high	Check dryer temperature controller and adjust if necessary

Part surfaces show pitting, but part surface is otherwise clean

Possible Causes	Solutions
Metal surface is being attacked by aggressive chemistry	Switch to lower pH, lower alkalinity cleaner solution
	Switch to cleaner solution containing more corrosion inhibitors
	Add low-concentration corrosion inhibitor to rinse water
	Use a protective coat of machine oil for long-term parts storage

Part surfaces have starburst pattern

Possible Causes	Solutions
Part surface being damaged by ultrasonics	Decrease ultrasonic power
Part surface being damaged by ultrasonics	Increase ultrasonic frequency

Cleaning solution turns yellow or brown

Possible Causes	Solutions
Bath temperature too high	Check bath temperature controller and adjust as necessary
Cleaner concentration too high	Check cleaner concentration
Cleaning solution oxidized over time	Ambient air can cause certain cleaner formulations to oxidize and darken over time. This does not affect the usefulness or cleaning ability of the solution.
Cleaning solution loaded with too much emulsified oil	Check soil levels. If necessary, dump cleaning solution and clean out reservoir to remove soil sediment. Refill with fresh cleaning solution.

A film of oil develops on top of the cleaning solution

Possible Causes	Solutions
Cleaner concentration too low	Check cleaner concentration and adjust as necessary
Bath temperature too low	Check bath temperature controller and adjust as necessary
Oil-phase de-foaming agent added	If an oil-based de-foaming agent is in use, the film of oil on top of the solution is there to prevent the formation of foam
Oil loading in cleaner tank too high	Check soil levels. If necessary, dump cleaning solution and clean out reservoir to remove soil sediment. Refill with fresh cleaning solution
Cleaner chemistry not compatible with soils being cleaned	Switch to a different cleaner that is chemically compatible with the base material and soils being cleaned.

Excessive foam

Possible Causes	Solutions
Too much agitation	Decrease agitation until foaming stops
Spray pressure and volume too high	Check pressure and flow regulators and adjust if necessary
Recirculation pump cavitating	Check condition of pump and check for flow blockage
Cleaner concentration too high	Check cleaner concentration and adjust as necessary
Bath temperature too low	Check bath temperature controller and adjust as necessary
Cleaner de-foaming agents used up	Replenish de-foaming agents
Foaming soil or additive introduced to bath	If soil is naturally foaming, a different cleaner formulation may be required, or additional de-foaming agents may need to be used.

Parts have a film of oil when removed from the cleaning solution

Possible Causes	Solutions
Parts not completely cleaned	See above recommendations for Part is not clean
Oil loading of cleaner bath too high	Check soil levels. If necessary, dump cleaning solution and clean out reservoir to remove soil sediment. Refill with fresh cleaning solution
Oil contamination of rinse water	Check rinse water to make sure only clean water is used for parts rinsing
Parts have excessive grease or heavy oils before cleaning	Add pre-cleaning step to remove excessive grease and heavy oil from parts
Cleaner chemistry not compatible with soils being cleaned	Switch to a different cleaner that is chemically compatible with the base material and soils being cleaned.

Parts have a white film or powdery residue

Possible Causes	Solutions
Parts not sufficiently rinsed after cleaning	Check rinse water to make sure only clean water is used for rinsing
	Increase rinsing time or add second rinse stage
	Increase rinse water flow or agitation in rinse tank.
Hard water scale forming on parts	Install water conditioners on the processing line
Hard water scale forming on parts	Switch to a different cleaner that has better hard water tolerance.
Silicates precipitating on parts	Switch to a different cleaner that does not use silicates.

Excessive scale buildup on tank fixtures or heater

Possible Causes	Solutions
Hard water scale	Install water conditioners on the processing line
Hard water scale	Switch to a different cleaner that has better hard water tolerance.
Silicates precipitating on parts	Increase maintenance routines to clean scale off more frequently
Silicates precipitating on parts	Switch to a different cleaner that does not use silicates.

Part surfaces appear grainy after cleaning

Possible Causes	Solutions
Part is being etched by galvanic action between dissimilar metals	Verify that all equipment and cleaning tanks are properly grounded. Verify that part baskets or fixturing are properly grounded
Part is being attacked by aggressive cleaner chemistry	Switch to a cleaner that is compatible with the base metal of the parts.

Color of alloy changes after cleaning

Possible Causes	Solutions
Part is being anodized by galvanic action between dissimilar metals	Verify that all equipment and cleaning tanks are properly grounded. Verify that part baskets or fixturing are properly grounded
Part is being attacked by aggressive cleaner chemistry	Switch to a cleaner that is compatible with the base metal of the parts.

Cleaner tank begins to rust at comers

Possible Causes	Solutions
Galvanic action is corroding metal of cleaner tank	Verify that all equipment and cleaning tanks are properly grounded

Cleaner system begins to leak

Possible Causes	Solutions
Galvanic action is corroding metal of cleaner tank	Verify that all equipment and cleaning tanks are properly grounded
Rubber gaskets and seals being attacked by oils removed from parts	Verify all seals used in cleaning equipment are compatible with the oils and solvents being removed from parts at the temperatures being used