Failure Analysis

Membranes and Seals

Failure Analysis

Membrane failures can be categorized by:

INSTALLATION PROBLEM

LOSS OF NITROGEN CHARGE

EXCESSIVE NITROGEN CHARGE

HEAT FAILURE

CONTAMINATION

BLANK FIRING

Membranes

Failure Analysis

Membranes are identified with manufacturing data and stamped “gas side” for proper installation.

Proper InstallationNitrogen “gas” side

MEMBRANE INSTALLATION FAILURE

Improper installation

Failure Analysis MEMBRANELOSS OF N2 CHARGE

Failure appears to originate on centersection of membrane.

Loss of Nitrogen thru a damaged U-sit seal is caused by over torque (15 ft-lb) during charging procedure.

Rim area tears allowing oil to enter nitrogen chamber and push membrane thru screen.

N2 gas escapes

Rim tear

Screen

Failure Analysis MEMBRANEBLANK FIRING

Blank firing occurs when the tool is not in full contact with pistonduring firing cycle.

Oil volume from the accumulator pushespiston past impact point with tool.

The oil volume normally retained betweenthe membrane and screen is lost and the membrane contacts the screen.

The membrane extrudes thru the screen until a hole is developed.

Membrane

Screen

Failure Analysis MEMBRANE EXCESSIVE CHARGE

Failure is caused by over charging nitrogen gas in accumulator. Inspection of membrane: Screen contact surface is ripped and an has an overall fish scale appearance.

Failure Analysis MEMBRANECONTAMINATION

Contamination in hydraulic oil can puncture the membrane.

Foreign particles from: Quick couplersExposed hose end fittingsDirty oil

Failure Analysis MEMBRANEHEAT FAILURE

Operation: Hammering in one spot to long.

Installation kit: Line size to small for oil volume. Hose damage causing restriction. Quick coupler failure. Ball valve partially closed.

Carrier hydraulic circuit. Pump worn out. Relief valve to low or fatigued.

Internal to hammer. Piston seizures.

Heat is always a symptom of a bigger problem.

Failure Analysis SEALS

Inspection of seals allows analysis of failure mode.Seal change color with time and oil temperature.

New 0 hours 1000 hours

Failure Analysis SEAL FAILUREHEAT

Heat failure caused by : Relief valve problem. High operating temperature. Low cooling capacity. Improper operation.