European Space Agency

Plastic Liners for Pressure Tanks

Objectives

The objective of the project was the design, manufacture and testing of an engineering model of a high pressure gas tank using a plastic liner. The plastic liner has to be compatible with Xe,He,N2 and must act as a gas barrier for these mediums. From a mechanical point of view, the liner has to be designed so that one can produce a tank with liner overwrapping without inside support.

The scalability of the 40l engineering model tank to a 90l tank should be demonstrated with a mathematical analysis.

Challenges

The plastic material of the liner has to have a low permeation. Furthermore, the liner has to be designed to ensure a reliable, low-cost producibility. Development tests on material samples supported the liner design and material selection.

Benefits

The main benefits of the developed pressure tank with plastic liner are the low manufacturing costs and also the shorter production and lead time of the tank compared with metallic liner tanks.

Features

The developed tank consists of a Polyamide (PA) plastic liner, manufactured through the Extrusion Blow Moulding process. Two metallic bosses, one on the tank port-side as an adapter for test setup and one on the tank end-side as an adapter for the composite winding machine, are attached to the plastic liner. The bosses are fixed, when the liner is finally overwrapped with composite.


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Plan

The plastic liner of the pressure tank has be designed to replace the current metallic liner – in particular in respect of:

  • Lead time for a tank
  • Costs (production costs)

Current status

The current design of the developed Engineering Model of the High Pressure Tank with Plastic liner has a cylindrical shape with a length of about 940mm and a diameter of 260mm.

The outcoming tank content is 39 liter. The tank has a total weight of 11kg (including metallic I/F adapter). The plastic liner only has a weight of 2,4kg.


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The total tank has a measured leak rate of 1,6 x 10-2mbar.l/sec 5 years. That means that still 134,4bar He ( 67% of 200bar test pressure) is available after the period.

There is still room for improvement in the leak rate, which could be decreased by modifications on the junction of the headstock boss to the plastic liner.

Status date

Tuesday, May 21, 2013 - 14:34