Glass Fiber Folded PALL Replacement Filters for Steel & Power Plant Hydraulic Precision Filtration

Glass Fiber Folded PALL Replacement Filters for Steel & Power Plant 

Hydraulic Precision Filtration

1. Working Condition Characteristics & Core Matching Logic

1.1 Harsh Medium Environment of Steel & Power Station Hydraulic Systems

Hydraulic stations of hot rolling mills, continuous casters, blast furnace auxiliary equipment in steel plants, and EH oil stations, turbine lubrication systems, boiler actuators in thermal power plants operate under continuous complex load conditions, where high-performance Replacement PALL Filter Elementsserve as core spare parts to sustain qualified oil cleanliness:

Continuous oil temperature ranges from 90℃ to 120℃, with instantaneous thermal peaks up to 130–150℃ caused by furnace radiation, sudden load surges and insufficient cooling circulation;

Pollutants in hydraulic oil include iron oxide abrasive particles, metal wear debris, varnish, oil sludge, sulfide corrosive substances and tiny pipeline rust fragments;

Frequent pressure fluctuation, cyclic flow impact and intermittent high-flow shock will cause fatigue damage to filter media with poor structural strength;

Strict cleanliness requirements for servo valves and precision actuators, requiring stable long-term oil cleanliness per ISO 4406 standard.

Ordinary single-layer paper filter elements or low-strength thin glass fiber media face multiple irreversible failures in such working conditions: rapid differential pressure rise due to insufficient dirt holding capacity, resin thermal decomposition leading to fiber delamination, sealing aging leakage under high temperature, unstable filtration efficiency after long-cycle operation, resulting in scratch failure of precision valve spools and unplanned production shutdown. Only upgraded multi-layer composite Replacement PALL Filter Elements can resist high heat, abrasive pollutants and frequent hydraulic shocks to eliminate these hidden operational risks.

1.2 Core Advantages of Glass Fiber Pleated Pall Replacement Filter Elements

This interchangeable filter series adopts multi-layer gradient borosilicate glass fiber pleated media, and these professional Replacement PALL Filter Elements are fully consistent with the dimensional interface, installation size and internal valve parameters of original Pall HC/UE series filter elements, realizing direct plug-and-play replacement without modifying filter housings. The overall design targets the high-temperature, high-pollution, vibration-prone characteristics of steel and power plant hydraulic systems, focusing on four core performances: stable precision filtration, large dirt holding capacity, high temperature & pressure fatigue resistance, and medium compatibility with industrial hydraulic oil, phosphate ester fire-resistant oil and water-glycol fluid. For harsh metallurgical and thermal power working conditions, wear-resistant long-service-life Replacement PALL Filter Elements can effectively reduce frequent replacement frequency and system failure risks. This document systematically interprets media grading parameters, structural matching standards, on-site working condition classification selection, operation parameter control and common fault disposal.

2. Graded Technical Parameters of Multi-Layer Gradient Glass Fiber Pleated Media (Core Filtration Barrier)

All glass fiber media comply with ISO 16889 multi-pass filtration test standard and ISO 3724 flow fatigue test standard, divided into three temperature-resistant grades according to oil temperature of steel and power plant hydraulic stations. The gradient asymmetric pore structure realizes step-by-step interception of pollutants: coarse outer fiber layer traps large metal debris, middle fiber layer adsorbs oil sludge and oxide colloid, dense inner fiber layer intercepts micron-level fine abrasive particles, avoiding rapid surface blockage.

2.1 Grade 1: Standard Medium-Temperature Glass Fiber Media (For oil temperature ≤100℃, cold rolling auxiliary & low-load power plant lubrication stations)

Composite structure: 3-layer homogeneous gradient borosilicate fiber, low-temperature cross-linked phenolic resin full impregnation;

Quantitative performance indicators:

Continuous stable operating temperature range: -10℃ ~ +100℃; resin thermal deformation temperature 112℃;

Filtration efficiency: βₓ≥200 (interception efficiency ≥99.5%) for 1/3/5/7/10μm optional precision;

High-temperature aging benchmark: After 500h constant temperature immersion in 100℃ industrial hydraulic oil, media tensile strength retention ≥83%, filtration efficiency attenuation ≤3%;

Dirt holding capacity: 1300–1500g/㎡, pleated structure expands effective filtration area by 3–4 times compared with flat media of the same outer diameter;

Matching accessories: NBR nitrile rubber sealing ring, galvanized perforated steel support skeleton, polyurethane end cap adhesive;

Applicable working conditions: Cold rolling finishing hydraulic stations, low-temperature circulating lubrication systems of small auxiliary power units, flue gas fan hydraulic stations with stable oil temperature below 95℃ and no furnace radiation heat source interference.

2.2 Grade 2: Reinforced High-Temperature Glass Fiber Media (Mainstream matching for hot rolling lines & conventional power plant EH oil stations, oil temperature 100–120℃)

Composite structure: 4-layer thickened gradient high-temperature modified borosilicate glass fiber, high cross-linking heat-resistant phenolic impregnating resin with solid content 14–16%;

Quantitative performance indicators:

Continuous long-term safe operating range: -10℃ ~ +120℃; resin thermal deformation temperature reaches 138℃, retaining 18℃ safety margin above the continuous temperature limit;

Transient peak temperature tolerance: Short-time instantaneous oil temperature up to 130℃, single continuous duration ≤30min without resin softening or fiber interlayer dislocation;

High-temperature aging benchmark: After 1000h alternating cyclic immersion of 110℃ constant temperature + 130℃ short thermal shock, media tensile strength retention ≥91%, filtration efficiency attenuation ≤1.8%;

Anti-oil-sludge characteristic: Surface calendering treatment forms a dense isolation layer, high-temperature oxidized oil sludge only accumulates on the outer fiber surface without deep embedding;

Matching accessories: FKM fluororubber high-temperature sealing ring, 304 stainless steel seamless rolled skeleton, fluorine-containing epoxy hot-melt end cap adhesive;

Applicable working conditions: Medium-load hot rolling roughing mill hydraulic systems, continuous casting secondary cooling hydraulic stations, conventional thermal power unit EH fire-resistant oil stations with oil temperature fluctuating 105–120℃ and occasional instantaneous temperature surges caused by equipment heat radiation.

2.3 Grade 3: Ultra-High Temperature Customized Glass Fiber Media (For furnace front heavy-load hydraulic stations & peak-temperature power plant boiler actuators, oil temperature 120–140℃)

Composite structure: Modified high-temperature glass fiber substrate with PTFE anti-oxidation isolation thin film on the surface, full fluorinated anti-acid & anti-oxidation finishing;

Quantitative performance indicators:

Continuous ultimate temperature resistance: -10℃ ~ +140℃; PTFE auxiliary film maintains stable performance below 260℃, isolating acidic oxidation by-products generated by high-temperature oil decomposition;

Transient peak tolerance: Instantaneous oil temperature up to 150℃, single duration within 20min without media performance attenuation;

Coupled aging resistance index: After 1200h immersion in 140℃ high-temperature oxidized hydraulic oil containing sulfide impurities, fiber strength retention ≥96%, no embrittlement or perforation risk under long-term thermal shock;

Matching accessories: Modified full-fluorine FKM sealing ring, 316L molybdenum-containing stainless steel anti-corrosion skeleton, high-temperature resistant integral injection molded end cap;

Applicable working conditions: Heating furnace front hydraulic cylinder systems, heavy roughing mills with insufficient cooling circulation, boiler main actuator hydraulic stations of thermal power plants with long-term oil temperature above 125℃ and frequent 140–150℃ instantaneous thermal spikes.

2.4 Performance Degradation Replacement Judgment Threshold of Glass Fiber Media

When the filter element operates beyond the rated temperature and pollution load for a long time, any of the following measurable indicators indicates complete attenuation of filtration performance and mandatory batch replacement:

Media tensile strength retention drops below 75% after high-temperature aging; fiber becomes brittle and prone to tearing under system cyclic flow fatigue impact;

Filtration β value attenuation exceeds 10% within one service cycle; fine abrasive iron powder penetrates the media and causes continuous scratch failure of downstream precision servo valve spools;

Initial differential pressure of new filter element rises more than 120Pa compared with factory calibration value, indicating resin thermal softening narrows fiber pore channels and forms permanent flow resistance increase.

3. Full Set High-Temperature Matching Structural Accessories (Consistent Interchangeability with Original Pall Filter Elements)

The complete filter assembly’s temperature and pressure resistance depends on the coordinated matching of media, sealing rings, end cap adhesive, support skeleton and built-in bypass valve; mismatched accessories will cause oil leakage and bypass pollution before media aging, and all structural dimensions maintain interchangeability with original Pall HC/UE series filter housings.

3.1 Graded High-Temperature Sealing Ring Matching

NBR nitrile rubber standard seal (only matched to Grade 1 ≤100℃ media): Continuous operating temperature -40℃ ~ +100℃, instantaneous peak maximum 110℃; long-term operation above 105℃ leads to sharp drop of compression rebound rate, rubber hardening and micro-cracking, volume swelling rate reaches 16–22% after 500h immersion in high-temperature oxidized oil, forming tiny oil leakage gaps at end cap assembly surfaces; prohibited for hot rolling and power plant high-temperature hydraulic circuits above 100℃.

Standard FKM fluororubber high-temperature seal (matched to Grade 2 120℃ mainstream media): Continuous stable operation -20℃ ~ +120℃, short-time instantaneous peak tolerance up to 130℃; volume swelling rate ≤3% after 1000h immersion in 120℃ industrial hydraulic oil, compression rebound rate ≥92% after alternating cold-hot temperature cycles, resisting acidic oxidation by-products produced by high-temperature oil decomposition.

Modified full-fluorine FKM special seal (matched to Grade 3 140℃ ultra-high temperature media): Continuous long-term safe temperature -20℃ ~ +140℃, transient peak up to 150℃; optimized anti-oxidation molecular chain structure, no elastic loss under long-term furnace radiation high-temperature immersion, compatible with aged high-viscosity oxidized hydraulic oil in steel and power plant heavy-load stations.

3.2 End Cap Bonding Adhesive Technical Index

Two types of adhesives differentiated by temperature grade are used for full-circumference bonding of end cap and glass fiber media:

Standard polyurethane adhesive (matched with NBR seal, ≤100℃): Heat resistance ceiling 110℃; long-term immersion above 105℃ will hydrolyze and delaminate, forming internal bypass channels for unfiltered high-temperature oil.

High-temperature fluorine-containing epoxy hot-melt adhesive (matched with FKM series seals, ≥120℃): Continuous temperature resistance up to 145℃, peel strength ≥50 N/cm; no degumming separation under 130℃ cyclic thermal shock, eliminating hidden danger of high-temperature oil short-circuit pollution in hydraulic systems of steel mills and power plants.

3.3 Built-In Bypass & Anti-Drain Valve Calibration Parameters

All interchangeable filter elements integrate stainless steel spring valve cores and rubber valve gaskets, whose temperature resistance must be consistent with the main sealing material grade; the opening pressure setting (standard 3bar ±10%) is fully consistent with original Pall parameters to ensure equipment protection consistency:

NBR valve gasket standard version: Valve opening pressure tolerance drifts ±0.5 bar at 100℃; above 110℃, the gasket softens and the bypass opening pressure drifts seriously, losing overload protection function when the filter element is fully blocked.

FKM fluororubber valve gasket high-temperature version: Valve opening pressure remains stable within the full range of -10℃~130℃; stainless steel spring elastic coefficient does not change under long-term high-temperature oil immersion, no jamming failure under full-blockage high differential pressure of steel and power plant hydraulic systems.

3.4 Support Skeleton Anti-Temperature & Anti-Corrosion Matching

Two skeleton grades are configured for different thermal load and humidity environments of steel and power plants:

Galvanized carbon steel skeleton (≤110℃ light thermal load): Galvanized layer peels off under long-term 120℃ high-temperature oil immersion, rust debris falls into hydraulic oil and aggravates secondary system pollution; only applicable to low-temperature clean lubrication circuits of auxiliary equipment.

304/316L stainless steel thickened perforated skeleton (≥110℃ hot rolling & power plant main hydraulic stations): Wall thickness ≥1.2mm, seamless rolled integral forming without spot welding crevice corrosion points; consistent thermal expansion coefficient with glass fiber media, no inward deformation and pleat compression under high differential pressure; 316L molybdenum-containing material is selected for high-humidity power plant pump rooms to resist condensate chloride pitting corrosion.

4. Graded Selection Scheme for Typical Steel & Power Plant Hydraulic Working Conditions

Working Condition 1: Cold rolling auxiliary hydraulic station, continuous oil temperature ≤100℃, instantaneous peak ≤105℃

Matching filter element: Grade 1 standard glass fiber pleated media + NBR nitrile rubber seal, interchangeable with original Pall HC/UE low-temperature series;

Operation restriction: Install heat insulation baffles around filter housings to avoid direct radiation heat transfer from furnace doors; regularly drain accumulated water at the bottom of oil tanks to reduce medium moisture content.

Working Condition 2: Conventional hot rolling roughing/finishing line, power plant EH oil station, continuous oil temperature 100–120℃, instantaneous peak 125–130℃, single peak duration ≤30min

Matching filter element: Grade 2 reinforced high-temperature glass fiber pleated media + standard FKM fluororubber seal, mainstream interchangeable replacement scheme for 90% of steel hot rolling and thermal power main hydraulic systems;

Operation restriction: Optimize hydraulic oil cooling circulation flow to avoid continuous oil temperature exceeding 120℃ for more than 4h; record differential pressure per shift to track media aging speed.

Working Condition 3: Heating furnace front heavy-load hydraulic cylinder station, boiler main actuator hydraulic station, continuous oil temperature 120–140℃, frequent 140–150℃ transient thermal peaks

Matching filter element: Grade 3 ultra-high temperature full fluorine composite glass fiber media + modified high-temperature FKM seal + 316L stainless steel skeleton, customized interchangeable filter element for extreme thermal load working conditions;

Operation restriction: Add auxiliary oil cooling heat exchangers to limit average oil temperature below 130℃; shorten filter element replacement cycle by 30% compared with medium thermal load working conditions.

5. Core System Operation Parameter Control Standards to Extend Service Life

5.1 System Flow Velocity Limit

High-temperature hydraulic oil has low viscosity; excessive flow velocity intensifies thermal scouring and fatigue impact on glass fiber pleated media:

Grade 1 medium-temperature media flow velocity ≤0.8 m/min, reserve 20% flow margin;

Grade 2 reinforced high-temperature media flow velocity ≤0.7 m/min, reserve 25% flow margin;

Grade 3 ultra-high temperature media flow velocity ≤0.6 m/min, reserve 30% flow margin to reduce fiber fatigue damage caused by high-speed oil flow impact.

5.2 Compressed Air Purification Standard for Online Backwash (If Equipped)

For hydraulic systems with filter element online backwash function, the backwash air source must be equipped with refrigerated dryer + double-stage oil-water separator, air source dew point ≤-20℃, residual oil ≤0.1ppm; oil-containing air will form tar sticky layers on glass fiber media surface, accelerate pore blockage and shorten service life by more than 40%. Backwash pressure shall be controlled within 0.4–0.5MPa to avoid pleat collapse and fiber breakage.

6. Common Mismatch & High-Temperature Failure Cause Analysis & Disposal Solutions

Fault 1: End cap oil leakage after short-term use, sealing ring hardening and surface cracking

Root causes: NBR standard sealing ring mismatched for hydraulic circuits with oil temperature above 100℃; filter housing is continuously heated by furnace radiant heat without heat insulation protection.

Solutions: Replace the full filter element with FKM fluororubber high-temperature interchangeable version; wrap 20mm thick heat insulation cotton outside the filter housing to isolate external radiant heat.

Fault 2: Filter element differential pressure surges rapidly, filtration efficiency declines, servo valve spools scratch frequently

Root causes: Low-temperature ordinary glass fiber media applied under continuous 120℃ oil temperature; impregnating resin undergoes thermal decomposition leading to fiber interlayer separation, fine metal dust penetrates downstream; cooling circulation system fails to stabilize oil temperature.

Solutions: Upgrade to Grade 2 reinforced high-temperature glass fiber interchangeable filter elements; overhaul the hydraulic oil cooling system to stabilize continuous oil temperature below 120℃.

Fault 3: Hydraulic pump vibrates abnormally when filter element is blocked, bypass valve fails to open normally

Root causes: NBR valve gasket matched for high-temperature oil circuits; high-temperature softening causes large drift of bypass opening pressure; long-term oil sludge adhesion on valve core leads to jamming.

Solutions: Replace the integral interchangeable filter element with full FKM high-temperature valve assembly; shorten online backwash cycle to remove oil sludge deposits inside the filter housing.

Fault 4: Rust debris falls into hydraulic oil and causes secondary system pollution

Root causes: Galvanized carbon steel skeleton selected for high-humidity high-temperature pump rooms of steel mills and power plants; condensed water vapor and high-temperature oil jointly peel off the galvanized protective layer.

Solutions: Replace with interchangeable filter elements equipped with 304/316L thickened stainless steel skeletons; regularly drain accumulated water at the bottom of the hydraulic oil tank to reduce system internal humidity.

7. Standardized Daily Maintenance Specifications

Weekly heat insulation inspection: Check the integrity of filter housing heat insulation layer, repair exposed metal shells in a timely manner to avoid direct radiant heat heating of filter elements.

Shift differential pressure recording: For hot rolling furnace front and power plant EH high-temperature hydraulic stations, record real-time filter element differential pressure data per shift to track the aging speed of glass fiber media.

Prohibited operations that damage high-temperature performance:

Forbid high-pressure air gun external flushing of disassembled filter elements: Scratches the high-temperature resin impregnation layer of glass fiber media, accelerates thermal decomposition failure;

Forbid water cleaning or solvent soaking high-temperature filter elements: Cleaning agents corrode FKM fluororubber seals and high-temperature epoxy adhesive, leading to degumming and leakage after reinstallation;

Forbid mixed assembly of NBR standard sealing rings on high-temperature interchangeable filter elements, which completely invalidates the 120℃+ temperature resistance index.

Emergency cleaning restriction: Only low-pressure (0.2MPa) internal backflushing emergency cleaning is allowed for slightly blocked filter elements, with a maximum of 2 repetitions; repeated cleaning will wear the media surface protective resin layer and advance the replacement cycle by 30–50%.

Seasonal correction rule: Ambient temperature rises in summer, furnace radiant heat intensifies, and the filter element replacement cycle shall be advanced by 20–30% to prevent over-temperature failure.

8. Summary

The overall performance of glass fiber pleated interchangeable filter elements for original Pall products under high-temperature hydraulic working conditions of steel mills and power plants is jointly determined by four core parts: graded heat-resistant glass fiber media, fluororubber high-temperature sealing system, high-temperature epoxy bonding structure and stainless steel anti-corrosion support skeleton. The core temperature boundary for safe continuous operation is 100℃: NBR-sealed standard filter elements are only suitable for low-temperature auxiliary stations below 100℃, while hot rolling lines, continuous casting equipment and power plant EH main hydraulic stations with oil temperature exceeding 100℃ must select interchangeable filter elements matched with FKM fluororubber and reinforced high-temperature glass fiber media (continuous temperature resistance 120℃) or customized 140℃ ultra-high temperature versions.

Field maintenance personnel shall select corresponding temperature-resistant grades of interchangeable filter elements according to the long-term average oil temperature and instantaneous peak thermal load on site, cooperate with filter housing heat insulation transformation and hydraulic oil cooling circulation optimization, strictly implement differential pressure patrol monitoring and advance replacement rules, effectively avoid media thermal embrittlement, sealing oil leakage and bypass valve jamming failures caused by over-temperature operation, stabilize the cleanliness of high-temperature hydraulic oil in rolling production lines and power generation units, reduce wear of precision hydraulic components and unplanned shutdown losses, and lower the comprehensive operation and maintenance cost of filter consumables.