Interlayer bubbling peeling failure refers to corrosive medium, water vapor and gas penetrating into the bonding gap between PFA lining and steel substrate through lining pinholes, microcracks and flange gaps. The trapped substances are gasified and expanded under heating conditions, forming high-pressure bubbles between the lining and the base pipe. The lining is jacked up into obvious bulges. As internal pressure accumulates continuously, the bonding interface peels off in a large range, and the bulged lining is torn and broken under fluid scouring or pressure impact, triggering medium leakage and lining fragment blockage. This defect is a typical secondary failure derived from lining micro-defects, which is common in lined pipelines with incomplete sealing and tiny penetration points.
1. Medium Infiltration and Bubble Expansion Failure Mechanism
The intact sintered bonding layer can completely block external medium infiltration. Once the lining has tiny through defects, process liquid and water molecules will permeate into the interlayer under pressure. When the pipeline heats up, the infiltrated liquid vaporizes into gas, and the volume expands dozens of times, forming closed high-pressure air bags between lining and steel pipe. The bonding force cannot resist the jacking force of internal bubble pressure, so the lining gradually separates from the pipe wall and forms bulges. After cooling, the gas condenses into negative pressure, which further aggravates lining degumming. Unlike thermal expansion buckling caused by thermal stress of the lining itself, this damage is driven by gas pressure generated by foreign matter entering the interlayer.
2. Typical Positions Prone to Bubbling Damage
Flange flanging root gaps where medium easily seeps into the interlayer along the edge;
Lining pinhole and spark detection missing points formed during factory processing;
Crack damage positions after water hammer impact and mechanical scratch on the lining surface;
Welded repair positions of lining with poor sealing and weak anti-permeation ability;
Dead leg pipelines with long-term static medium accelerating infiltration into tiny defects.
3. Core Inducing Factors Accelerating Bubbling Failure
Factory spark leakage detection and air tightness test are not fully implemented, leaving hidden penetrating micropores;
Flange installation gasket is mismatched, leading to medium creeping into the lining edge interlayer;
Lining is scratched and cracked during transportation and hoisting without repair and sealing treatment;
System temperature rises sharply after shutdown and standby, causing rapid vaporization of infiltrated liquid;
Long-term operation without internal inspection, small infiltration points gradually evolve into large-area bubbling peeling.
4. Full-Link Prevention and Control Technical Measures
① Conduct 100% high-frequency spark hole detection and whole-section air tightness inspection before product delivery
Eliminate penetrating micropore defects from the factory source.
② Select size-matched anti-seepage gaskets for flange connections and control uniform bolt pre-tightening force
Block the channel for medium to invade along the flanging edge.
③ Formulate hoisting and transportation protection specifications to avoid hard object scratching the lining inner and outer surfaces
Repair and seal immediately once lining damage is found.
④ Adopt segmented slow temperature rising operation to prevent sudden vaporization and instantaneous pressure surge of interlayer infiltrant
Reduce the growth driving force of interlayer bubbles.
⑤ Carry out periodic endoscopic inspection and pressure difference testing for key pipeline sections
Discover small bulges and hidden degumming areas in advance before large-area peeling.
5. Prevention Effect Comparison Table
表格
| Inspection & Installation Mode | Interlayer Bubbling Risk | Application Suggestion |
|---|---|---|
| Unfinished flaw detection + non-standard flange sealing + lining surface damage | Obvious bulging and lining rupture leakage occur within medium service cycle | Replace defective pipe fittings and re-do full pipeline flaw detection and sealing rectification |
| Strict factory non-destructive testing + standardized flange sealing + finished product protection management | Effectively cut off medium infiltration path and inhibit interlayer bubble generation | Standard quality control specification for PFA lined pipe prefabrication and field installation |
| Modified high-density anti-permeation lining + whole-line online pressure monitoring + annual internal video inspection | Extremely low interlayer bulging and lining shedding blockage hidden danger | Preferred scheme for high-temperature and high-pressure anti-corrosion heating pipeline engineering projects |
Conclusion
PFA lining interlayer bubbling delamination failure is caused by medium penetrating the lining defects into the bonding interlayer, which vaporizes and expands under heating to form jacking pressure and separate the lining from the steel pipe. Core prevention approaches include strict factory defect detection to eliminate micropores, standardizing flange sealing to prevent edge infiltration, protecting lining integrity during construction, avoiding rapid temperature rise and strengthening regular internal inspection. Whole-process closed-loop management of product ex-factory inspection, on-site assembly construction and daily operation maintenance can prevent pipeline blockage and medium leakage safety accidents caused by interlayer bubbling peeling of PFA lined heating tubes.
