Brewer & Distiller International Article

A recent article in the Brewer & Distiller International magazine explored new developments in keg manufacture, with GPS plastic kegs and casks being featured. Read the full article here or alternately, read on below:

The Keg in 2012

Various changes in the materials of keg manufacture away from stainless steel have been initiated in the last few years, largely driven by financial stimuli.

The spectacular rise in the market price of nickel (the grades of stainless used for kegs contain of the order of 8–12% nickel) followed by the credit crunch, have made any source of stainless steel very attractive to thieves, this black market being driven by a perceived opportunity for any grade to supply the inexhaustible demand of the so-called ‘emerging markets’.

As an example, when nickel prices were at their highest in 2007, the UK container population then owned by TrenStar was ‘shrinking’ by up to 15-20% per annum. Whereas Franke Beverage Systems has concentrated recently on producing a lightweight, and thereby cheaper, keg (as an example, its latest 20-litre keg weighs approximately 50% of their equivalent traditional unit), other initiatives world-wide have moved into plastic kegs, both one and multi-trip.


Multi-trip Kegs


Plastic multi-trip containers are usually manufactured in high density polyethylene (HDPE) in one of two ways, either injection moulding of two part-shells which are secured via adjoining male and female butts, or blow moulding of a complete ‘bottle’. The first of these methods is fraught with difficulties, as any subsequent keg impact can rupture the unit. The second method, as practised by Global Polymer Solutions, yields a very robust keg that has an extremely high resistance against gravitational impact, the results of laboratory drop-tests being at least as good as an equivalent unit in stainless steel.

Being constructed in plastic, the unit tends to deform on impact but because of is elasticity soon returns to its former shape. Other advantages of using plastic rather than stainless-steel to manufacture containers are that:

  • Selling price is about 65% of a comparable stainless-steel unit.
  • Material costs are cheaper than stainless and far less price volatile. It would require a quadruple rise in oil prices to make a significant impact.
  • Unit weights are about half that of the stainless counterpart.
  • Container branding can be incorporated in the moulding process, and hence is more durable than the silk screen printing process used for metal containers.
  • HDPE is easy to recycle, most popularly by shredding and remoulding into locator boards.
  • As a consequence of the designed keg wall thickness, migration of gases into and away from the liquid can be eliminated.


Final developments now nearing completion are aimed at ensuring that the standard criteria for resistance to hydraulic pressure, safe working pressure plus 50% (6.0 barg(2)) can consistently be achieved.

The design used by Global Polymer Solutions is based on a blow-moulded bottle, functioning as an inner pressure vessel, supported by injection-moulded outer sections which fit together and are locked by a central band to facilitate handling and provide additional strength to withstand the normal keg working pressures. The keg rolling rings are made from a polyurethane rubber which is extremely abrasion-resistant.


Expected life


One of the conundrums of keg performance criteria is its expected operational life. Without any external influences, metal kegs will easily survive the normal ‘book write-down’ life of around 15 years. There are many examples of aluminium kegs still working in the market place bearing manufacturing dates as far back as the 1960s. The major factors which detract from achieving such longevity are damage and theft, factors which are far less of an issue with plastic containers, for which accelerated tests
indicate a projected life of approaching 10 years.

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