May 15, 2006
Rust, wear, and dirt cost tube fabricators and producers millions of dollars annually, and they can be the bane of tube processes. Analyzing the criteria for selecting the lubricant, cleaner, and rust preventative can help provide maximum protection.
This guide is part of an article series "Flushing out four-letter words-rust, dirt, and wear; Part II: Removing soils effectively," by Mike Pelham, International Chemical Co., Philadelphia, reprinted from the June 2006 issue of The Tube & Pipe Journal®. The article addresses how to eliminate tube producing and fabricating problems related to dirt, rust, and wear. To read the article series online, enter "Pelham" in thefabricator.com search field.
Problem | Cause | Corrective Action |
Poor Cleaning | Mechanical | |
Plugged spray nozzles resulting in poor coverageLow pump pressure or damaged pump impeller. Insufficient coverage and inadequate direction of cleaner solutionExcessive foam | Inspect and clean nozzles; clean and descale washer if necessary Check, repair or replace impeller; adjust pump pressure See Foam section | |
Chemical | ||
Incorrect cleaner concentration; cleaning temperature too low Change in soils being cleaned; a new lubricant or coolant may not be effectively removed with the existing cleaner or at the current temperature | Adjust concentration to manufacturer specs; increase temperature. Evaluate cleaner and adjust temperature accordingly; cycle times may need to be monitored | |
Foam | Mechanical | |
Air leaks in the piping to the pump inlet or in the pump itself, causing aeration and/or cavitation of the cleaner solution resulting in excessive foaming Sump level is below pump intake level which causes aeration and subsequent foaming | Determine where the leak is and seal it; check all hose clamps for tightness Raise solution to correct level | |
Chemical | ||
Check cleaner concentration—it may be too low or high, depending on cleaner Incorrect cleaner temperature Contamination of cleaner solution with a foreign material | Adjust concentration to manufacturer's recommended level Adjust temperature to manufacturer's recommendations Use a defoamer as a short-term solution, then identify the contamination and cause of the foam. For a one-time occurrence, dump and recharge washer; if foam is continually changing, change cleaning product | |
Streaking or Spotting | Mechanical | |
Part configuration causes uneven coating; resulting in uneven washing Rinse nozzles misaligned Rinse temperature and/or cleaner temperature too high, causing flash drying or cleaner breakdown | Insert or adjust air blowoff; tilt or angle parts to facilitate drainoff of excess solution Adjust and modify nozzles Refer to manufacturers' requirements for correct temperature | |
Chemical | ||
Cleaner concentration elevated in the rinse because of excess carryover / flowover of cleaner on the parts or overspray running into rinse tank Cleaner cannot be removed effectively Cleaner or rinse temperature too high, resulting in detergent dry-on. Parts won't dry off | Tilt parts to facilitate excess drain-off Align nozzles to eliminate over spray Change to a nonsilicated cleaner; consult with cleaner manufacturer; check soils in bath Adjust temperature as required; consult cleaner manufacturer See Wet Parts section | |
Rusting of Cleaned Parts | Mechanical | |
Rust protective film rinsed from the work by fresh water Parts rusted before entering the washer Parts not clean Work left in the washer over a shutdown period Contact between wet parts Wet parts in general | Make sure cleaner concentration level per manufacturers recommendation Verify where parts came from in process and what may be the cause See Poor Cleaning section Ensure washer is free of parts before shutting down; keep washer doors open to reduce humidity Separate wet parts with dividers. A water-displacing rust preventive may be required See Wet Parts section | |
Chemical | ||
Incorrect cleaner concentration Incorrect cleaner for nature of soils | Adjust cleaner concentration to manufacturers' required level Consult cleaner manufacturer | |
Wet Parts | Mechanical | |
Air blowoffs out of alignment Rinse temperature too low Conveyor speed has increased | Adjust direction and temperature of air blowoffs Adjust temperature to manufacturer's recommendation If new rate is implemented, increase temperature and add or improve air blow off; consult with cleaner manufacturer | |
Hard Water | Cleaner not suited for use in high water-hardness; hardness or solids so high that residue remains in spite of cleaner | Change to suitable cleaner; use softened or deionized water in the rinse; use a rinse aid |