System Engineering / Pressure Equipment

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PED Professional 6

Vibration fatigue failures on a compressed gas bottle

   

Fig. 1
General view of the compressed gas bottle
Fig. 2
Cracks extending in axial direction on the inner surface of the pres-sure vessel
Fig. 3
Area from where the cracks have started, with the characteristics of vibration fatigue failure near the inner surface

 

Description:
Premature cracks have occurred in alternating load tests on a compressed natural gas bottle used as fuel tank for a motor vehicle, in the area of the cylindrical shell. The pressure vessel itself consists of an aluminum liner reinforced by a wrapping of fiberglass-reinforced plastics on its outer surface (Fig.1).  

Failure cause:
Die Schadensursache sind Schwingbruchrisse, die auf der Innenoberfläche des Druckgasbehälters starten (Abb.2). Die Schwingbrüche sind wanddurchdringend (Abb: 3). Wie metallographische Untersuchungen bestätigen, haben rissinitiierend kleine Korrosionsnarben auf der Innenoberfläche gewirkt.

Remedy:
It has been recommended to keep the surfaces of the aluminum liner free from defects in material. Particular care has to be dedicated to avoiding the development of pitting corrosion, in the production of the liner.

Our services – your benefits:
Knowing the cause of damage, the customer is in a position to aim his efforts for further development towards the introduction of his product in the market on corresponding improvements and on reducing a possible source of failure in future service of the product to a minimum.

Consulting services from:
TÜV SÜD Industrie Service GmbH