| Dry running or inadequate lubrication | Rapid leakage, discolored faces, heat checking, cracked carbon, or a sharp burnt odor. | Loss of liquid at the seal chamber, blocked flush path, incorrect startup sequence, or operation below the required liquid level. | Startup and trip history, seal-chamber level, flush-flow records, face color, and carbon-face condition. | Verify flush flow and pressure; inspect the seal faces and review operating conditions during startup and shutdown. | Evidence of thermal damage combined with documented loss of liquid or insufficient flush during the failure event. | Prevent dry operation, improve instrumentation, clear blocked lines, revise startup procedures, and select a seal arrangement suitable for the service. | High |
| Excessive heat generation | High leakage rate, face distortion, thermal cracks, elastomer hardening, or repeated failures after short operating periods. | Excessive closing force, inadequate cooling, high sliding speed, incorrect face combination, or excessive friction caused by contamination. | Process temperature, seal-face temperature, shaft speed, pressure, flush temperature, and face-wear pattern. | Compare actual speed, pressure, and temperature with the seal design limits; check cooling and calculate the operating duty. | Thermal damage is consistent with the calculated heat load and cooling capacity. | Restore cooling or flush capacity, correct operating conditions, reduce friction, and review the face materials and balance ratio. | High |
| Misalignment or shaft runout | Uneven face wear, localized wear bands, fretting, fluctuating leakage, or visible movement of the rotating assembly. | Pipe strain, worn bearings, bent shaft, incorrect assembly, soft foot, or excessive shaft runout. | Shaft runout, end play, bearing condition, coupling alignment, pipe-support condition, and seal-face wear pattern. | Measure shaft runout with a dial indicator, check alignment, inspect bearings, and verify pipe strain after installation. | Measured movement exceeds the seal or equipment tolerance and matches the observed non-uniform wear. | Correct alignment, remove pipe strain, repair bearings or shaft defects, and verify equipment tolerances before reinstalling the seal. | High |
| Vibration or unstable operation | Intermittent leakage, face opening, noisy operation, fretting marks, or accelerated wear of secondary seals. | Hydraulic instability, cavitation, resonance, unbalanced rotating parts, bearing defects, or operation away from the pump's stable region. | Vibration spectrum, operating point, suction conditions, bearing data, and the timing of leakage relative to speed or load changes. | Perform vibration analysis, check for cavitation, compare operation with the pump performance curve, and inspect rotating components. | Vibration or hydraulic instability occurs at the same operating conditions as the leakage or face-opening event. | Correct the hydraulic operating point, remove the vibration source, repair rotating components, and improve support or piping conditions. | High |
| Chemical attack or elastomer incompatibility | Swollen, cracked, softened, hardened, or permanently deformed elastomers; corrosion or discoloration of seal components. | Incorrect material selection, unexpected process chemistry, concentration changes, incompatible cleaning fluid, or excessive temperature. | Process composition, concentration, pH, temperature history, cleaning chemicals, and condition of elastomers and metal parts. | Compare chemical compatibility data with actual service conditions and perform laboratory examination of affected materials. | Material deterioration is consistent with exposure to the identified chemical and operating temperature. | Select compatible elastomers, faces, and metal parts; control chemical concentration and verify cleaning procedures. | High |
| Abrasive or particulate contamination | Grooves across seal faces, rapid wear, scratched surfaces, leakage that increases progressively, or blocked springs. | Solids in the process fluid, inadequate filtration, product crystallization, poor flush quality, or contamination introduced during assembly. | Particle type and size, filter condition, flush-fluid cleanliness, face scratches, spring condition, and equipment cleanliness. | Inspect faces microscopically, analyze deposits, check filtration, and verify flush pressure and flow direction. | Wear tracks and deposits contain particles capable of producing the observed abrasion or blockage. | Improve filtration or flushing, prevent crystallization, clean components thoroughly, and use faces or designs suited to solids service. | High |
| Pressure reversal or incorrect pressure balance | Unstable leakage, face opening, extrusion of secondary seals, or damage that changes with pressure fluctuations. | Incorrect seal orientation, pressure exceeding the design limit, reverse pressurization, blocked pressure-relief paths, or incorrect balance ratio. | Pressure at the seal chamber, suction and discharge pressures, transient events, seal orientation, and installation records. | Trend pressure during startup, shutdown, and upset conditions; verify the seal arrangement and calculate pressure loading. | Recorded pressure conditions exceed the design envelope or create a direction of loading not supported by the seal design. | Correct installation orientation, control pressure transients, restore relief paths, and select a pressure-rated arrangement. | High |
| Improper installation or assembly damage | Leakage immediately after installation, chipped faces, cut O-rings, loose components, or incorrect spring compression. | Dirty assembly area, damaged handling surfaces, incorrect dimensions, missing parts, over-tightened fasteners, or incorrect setting length. | Installation records, component measurements, gasket and O-ring condition, setting dimensions, and photographs before operation. | Compare assembly dimensions with the equipment drawing, inspect components under magnification, and verify installation sequence. | The defect is present before significant operating wear and corresponds to an assembly or handling error. | Standardize installation procedures, use clean tools and work areas, train technicians, and verify critical dimensions before startup. | Medium |
| Secondary-seal sticking, extrusion, or loss of movement | Leakage that changes with temperature or pressure, localized wear, torn elastomers, or evidence that the seal face cannot follow axial movement. | Elastomer swelling, hardened deposits, excessive clearance, pressure extrusion, corrosion, or incorrect secondary-seal material. | Elastomer hardness, surface condition, groove dimensions, pressure and temperature history, and deposits on sliding surfaces. | Inspect grooves and sliding surfaces, measure clearances, test elastomer condition, and compare material limits with service data. | Restricted movement or extrusion damage explains the loss of face contact under the recorded operating conditions. | Clean or redesign grooves, control clearances, select a compatible elastomer, and limit pressure and temperature excursions. | Medium |
| Corrosion or galvanic attack | Pitting, component thinning, spring failure, surface roughness, or leakage that worsens after extended service. | Incompatible metallurgy, aggressive chemistry, stagnant fluid, oxygen ingress, or galvanic coupling between dissimilar metals. | Corrosion morphology, process chemistry, metal composition, electrical contact between metals, and location of attack. | Conduct visual and microscopic inspection, identify materials, analyze deposits, and review corrosion-control conditions. | The corrosion pattern and material combination are consistent with the process environment or galvanic mechanism. | Use compatible materials, isolate dissimilar metals where appropriate, control chemistry, and eliminate stagnant or contaminated zones. | Medium |
| Normal wear or end-of-life degradation | Gradually increasing leakage, predictable face wear, reduced spring force, or performance decline after long service. | Expected wear from operating hours, fluid lubricity, sliding speed, pressure, temperature, or maintenance interval. | Operating hours, leakage trend, face-width measurements, spring condition, and maintenance history. | Compare wear measurements with historical data and expected service life; rule out thermal, chemical, and mechanical damage. | Wear is uniform, progressive, and consistent with service duration without evidence of a sudden abnormal event. | Set condition-based replacement criteria, monitor leakage, and review the maintenance interval using actual service data. | Low |
| Incorrect operating conditions or process upset | Failure follows a change in speed, pressure, temperature, fluid composition, flow rate, or startup and shutdown frequency. | Operation outside the design envelope, frequent cycling, pump cavitation, blocked discharge, or unplanned process changes. | Time-synchronized process trends, alarm history, operator logs, seal leakage records, and maintenance timestamps. | Perform a timeline analysis linking process changes to leakage, temperature, vibration, and pressure behavior. | The failure begins after a specific operating excursion and the excursion is technically capable of damaging the seal. | Control the process envelope, add alarms or interlocks, revise operating procedures, and reassess seal selection for actual duty. | High |
