Aerospace engine, propulsion system, aircraft hydraulic and fuel pipelines are ultra-high-grade precision piping. Tiny foreign objects remaining on the inner pipe walls, such as metal chips, welding slag, oxide scale and rolling oil contamination, pose direct risks to the safe operation of core components including rocket engines and servo valves. Conventional processes like pickling, solvent flushing and high-pressure purging suffer from blind cleaning spots, chemical residue, damage to precision inner surfaces and inability to collect or verify contaminants. The APS AM-2 pneumatic pipe cleaning gun, paired with custom high-density foam projectiles and a projectile collection unit, adopts a dry physical cleaning process. It has become the preferred solution for foreign object control, pre-delivery pretreatment and pre-assembly cleaning of precision pipelines in the aerospace industry.

1. System Composition

APS AM-2 Pipe Cleaning Gun Built with a lightweight aerospace-grade aluminum alloy body, it fits 5–50 mm aerospace stainless steel precision pipelines. Equipped with a full range of sealed adapter nozzles, it rapidly connects to various interfaces of aerospace conduits. Powered by dry compressed air or high-purity nitrogen with adjustable pressure, it adapts to clean workshop environments for aerospace manufacturing. Handheld operation by a single operator and storage inside a portable toolbox support batch pipe cleaning and on-site pipeline pretreatment.

Aerospace-Grade High-Density Foam Projectiles Made of highly elastic polyurethane, the outer diameter of each foam projectile is 10%–20% larger than the pipe inner diameter. Once inside the pipeline, elastic deformation enables tight contact with the pipe wall. Driven by airflow, the projectile travels forward at high speed while rotating, scraping off and stripping inner-wall contaminants in a full 360° coverage. The soft material prevents scratches on precision stainless steel surfaces and smoothly navigates complex aerospace piping geometries including 90° elbows, U-bends and tees, wrapping and carrying out welding slag, metal dust and oil sludge. Standard cleaning projectiles and abrasive foam projectiles are available for graded rough cleaning and fine cleaning according to specified cleanliness requirements.

Projectile Collection Unit Installed at the pipeline outlet, it features a sealed collection chamber and filter structure. Foam projectiles exiting the pipeline enter the collector directly, trapping projectiles and all captured contaminants to prevent secondary splashing and contamination inside cleanrooms. Operators can visually inspect projectile soiling to quickly assess cleaning quality. Contaminant sampling for pipeline cleanliness testing is supported, delivering visual and traceable cleaning results that meet aerospace archival requirements for foreign object control.

2. Working Principle

Powered by high-purity nitrogen or dry compressed air, a size-matched foam projectile is loaded into the chamber of the AM-2 cleaning gun, and the gun nozzle forms a sealed connection with the pipeline inlet. When the gas supply is activated, air pressure propels the foam projectile into the precision pipeline. The projectile stays pressed against the pipe wall and rotates as it advances, stripping foreign matter through compressive friction. Contaminants are encapsulated within the foam and carried out together into the collection unit. Multiple firing cycles can be performed repeatedly until discharged projectiles remain clean to complete the cleaning procedure. This fully dry physical process uses no water or chemical solvents. Pipes stay dry after cleaning with zero chemical residue and require no secondary drying, complying with strict cleanroom standards for aerospace production.

3. Core Advantages for Aerospace Applications

✅ Blind-spot-free cleaning for complex bent piping Aerospace propulsion pipelines feature abundant bends, reducers and tees. The deformable foam projectile navigates all irregular piping structures, resolving the recurring issue of residual contaminants at elbows and low points common in traditional flushing methods.

✅ Non-damaging cleaning to preserve precision inner walls Flexible foam material avoids scratching stainless steel precision pipe surfaces, generating no secondary metal debris and causing no corrosion, preserving the integrity of aerospace piping.

✅ Full contaminant capture for aerospace foreign object control The collector centrally contains foam projectiles and stripped pollutants to stop metal dust dispersion in clean workshops. Captured contaminants can be sampled directly for particle size testing, enabling verifiable and traceable cleaning records.

✅ Dry process with zero chemical residue Eliminates pickling and solvent immersion. No waste liquid or hazardous waste is produced. Pipes remain dry post-cleaning, removing risks of internal rusting and process fluid contamination caused by moisture or solvent residues.

✅ High efficiency suitable for batch pretreatment Single-pipe cleaning cycles are short. Batches of bent pipes and conduit prefabricated parts can be processed rapidly to shorten pretreatment lead times and match high-volume aerospace component production schedules.

4. Standard Operating Procedure for Aerospace Pipelines

Pipeline Pre-inspection: Visual inspection, removal of burrs at pipe ends, fixture mounting for both pipe ends. Connect the AM-2 cleaning gun to the pipeline inlet via a dedicated sealed nozzle and fit the projectile collection unit to the outlet. Projectile Selection and Loading: Select aerospace foam projectiles matching the pipe inner diameter and load them into the AM-2 gun. Graded Cleaning: Adjust gas supply pressure and launch foam projectiles. Use abrasive projectiles first for rough cleaning to remove welding slag and oxide scale, then pure white high-density foam projectiles for fine cleaning to progressively raise cleanliness levels. Cleanliness Verification: Check soiling on recovered foam projectiles inside the collector. Endoscopy and particle testing may be deployed as required to confirm compliance with cleanliness specifications. Pipe Sealing: Once inspection passes, seal both pipe ends to prevent recontamination before transferring to subsequent assembly workflows.

5. Application Scenarios

Widely deployed for production pretreatment, pre-assembly cleaning and maintenance cleaning of rocket engine fuel pipelines, hydraulic servo pipelines, precision aircraft instrument conduits, aerospace bent pipe prefabrications and propulsion system piping. It safeguards the cleanliness of aerospace fluid piping systems and eliminates critical safety hazards such as valve jamming and pipe abrasion triggered by microscopic foreign debris at the source.

6. Conclusion

Aerospace engineering imposes extreme requirements on pipeline cleanliness, and foreign object control is critical to mission success. The integrated dry physical cleaning solution combining the APS AM-2 pneumatic cleaning gun, foam projectiles and projectile collection unit balances powerful cleaning performance, pipe protection, contaminant containment and result validation. It delivers an efficient, safe and traceable new technical pathway for precision aerospace pipeline foreign object removal and supports quality control upgrades for high-end aerospace equipment manufacturing.