Saint-Gobain PAM SA v Fusion Provida Ltd
| Jurisdiction | England & Wales |
| Judge | Lord Justice Jacob,Lord Justice Scott Baker,Lord Justice Peter Gibson,LORD JUSTICE PETER GIBSON |
| Judgment Date | 25 February 2005 |
| Neutral Citation | [2005] EWCA Civ 177,[2005] EWCA Civ 258 |
| Court | Court of Appeal (Civil Division) |
| Docket Number | A3/2004/2441,Case No: A3/2004/2441 |
| Date | 25 February 2005 |
[2005] EWCA Civ 177
IN THE SUPREME COURT OF JUDICATURE
COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE HIGH COURT OF JUSTICE
CHANCERY DIVISION (PATENTS COURT)
The Hon Mr Justice Pumfrey
HC 04 C00060
Royal Courts of Justice
Strand, London, WC2A 2LL
Lord Justice Peter Gibson
Lord Justice Scott Baker and
Lord Justice Jacob
Case No: A3/2004/2441
Alastair Wilson QC and Peter Colley (instructed by Messrs Browne Jacobson Llp) for the Respondent/Claimant
Roger Wyand QC and Jonathan Hill (instructed by Messrs Bird & Bird) for the Appellants/Defendants
This appeal is from a judgment of Pumfrey J given on 3 rd November 2004. By the time the matter came before him the only issue was the validity of the European Patent (UK) No 0686246. It was and is accepted that if the patent is valid then the defendants (between whom there is no material difference) infringe. The Judge held the patent valid and accordingly infringed. The only issue is an obviousness attack.
The patentees, for whom Mr Wilson QC appeared, are Saint-Gobain PAM SA. This is a very large company in, inter alia, the underground pipe (typically for sewage or water supply) manufacturing business. The defendants are also in that business but are a much smaller enterprise. Mr Wyand QC argued their case.
Dates and other basic matters
The agreed priority date of the Patent is 18 th February 1993. It is accepted that the case turns solely on the obviousness or otherwise of claim 1. It is said to be obvious having regard to the disclosure in a paper called Johnsson published by the Swedish Corrosion Institute on 18 th December 1992 – just before the priority date.
Common General Knowledge
The Patent is directed to the "person skilled in the art" whose attributes I summarised at paragraphs 6–10 of Technip France's Patent [2004] RPC 46. There is no dispute about the kind of person involved. It is an unimaginative person (or team) in the research department of a company in the underground pipe manufacturing trade. He would have considerable knowledge of the problems of corrosion suffered by buried pipework.
Such a notional person would know, and have as part of his/her background knowledge that:
(a) It was obviously desirable that buried pipe should be resistant to corrosion over very long periods, not least because corrosion was not readily detectable in use and the cost of replacement generally higher than for accessible pipes.
(b) Such piping was typically made of cast iron.
(c) "Black pipe" was and had for many years been in widespread use as a successful form of corrosion resistant iron piping for buried use. It was made from three layers: the main, structural layer of ductile cast iron, a layer of Zn and a layer of bitumen.
(d) Absent the protective coating, the iron would corrode very readily, particularly in hostile (e.g. acid or saline) soil conditions. You hardly need to be a "skilled man" to know that!
(e) The protective coating of Zn was not provided by hot dipping or true galvanisation (i.e. electrolytic deposit). It was sprayed on and so was slightly porous. The outermost layer, sometimes called the "pore-sealing" layer was also slightly porous.
(f) For non-buried (above-ground or marine) iron or steel (which itself is mainly iron) a coating of Zn can provide protection by two distinct mechanisms. Firstly, it can simply act as a protective coating preventing water and oxygen from reaching the iron – like a coating of paint or bitumen. Second, however, there is the possibility, if the Zn coating gets wet, of electrolytic action. This is also called "galvanic" or "sacrificial" protection. When iron and Zn are in contact and the combination is in water containing an "electrolyte" (free ions, as for instance in acid conditions) the Zn will preferentially corrode. It is not necessary to explain more here – though every A-level (and probably GCSE) chemistry student will know this.
(g) In the case of black pipe a further anti-corrosion effect comes into play. Because it is slightly porous, the surrounding (corrosive) medium penetrates within the Zn. A rigid impermeable layer of Zn corrosion products forms. In due course all the Zn is consumed. So galvanic protection stops. But by then there is a layer of Zn corrosion products. This is itself so tough and coherent that it forms a physical barrier to corrosive products. This barrier lasts for many years. So one gets protection extending well beyond "the life" of the Zn.
(h) During the early period of this process another important and remarkable phenomenon occurs. It is hardly surprising that when pipe is being buried it is liable to take a few knocks and get scratched. So some of the underlying iron will get exposed. This is an obvious and serious danger – exposed iron should, in principle, corrode much faster than protected iron. But it turns out that the Zn corrosion products actually migrate to the exposed iron – to the site of the damage. The protective skin of Zn corrosion products builds up on this too. This is obviously very important indeed.
(i) There were particular problems with very acidic soils. In these the Zn corrosion product skin would not form. There was a need for a better form of corrosion protection for buried pipe – one that could cater for more stringent conditions than could the existing Zn based black pipe.
(j) Mixtures of Zn and Al (as an alloy) were also well-known for general use in corrosion protection. They had been used for years for above-ground and marine uses. But not for buried pipes. It was not known whether such an alloy would also form a protective corrosion skin or would do so as well as Zn alone. The purpose of the Al in the known uses was to slow down the erosion of Zn by galvanic effects.
The Patent in Suit
This begins by acknowledging a prior art proposal for an above ground steel pipe provided with a sacrificial Zn/Al surface covered with an epoxy resin. It goes on to say corrosion of ferrous metals by soil "is a phenomenon whose nature is different from atmospheric corrosion" and points out that soil conditions are diverse and that pipes may have their external surfaces damaged.
It then sets out the purpose of the invention:
"The purpose of the invention is to provide a coating technique for a buried iron-based pipe member which is suitable regardless of the purpose of the piping, particularly for water supply and drainage, in most types of soil, at an acceptable cost."
Next it sets out the invention in what is effectively claim 1, which I set out now:
"1. An iron-based, in particular cast iron, pipe member for buried piping, which is provided with an external coating comprising:
- a first porous layer of zinc/aluminium alloy containing 5 to 60% of aluminium; and on this first layer,
-a second porous layer, called the pore-sealing layer, based on organic or inorganic binder in aqueous, solvent or powder phase, between 100 and 140µm thick."
In the body of the specification there are two passages setting out the point of the invention:
"Through the action of corrosive agents in the soil this layer is converted into a protective layer of stable corrosion products in the environment in which it develops. The alloy layer is also called a "sacrificial" layer with respect to the cast iron, in the sense that it can be consumed progressively by oxidation as a result of the electrochemical cell formed by the cast iron, the alloy and the soil, to protect the cast iron underneath or bared at [sic] defects in the layer of zinc-aluminium alloy, through the formation of the said protective layer.
…… It has been found that the two-phase structure of the Zn/Al alloy favours the trapping of Zn corrosion products."
And
"The finishing layer, called the pore-sealing layer, is then deposited by spraying. This pore sealant both slows down corrosion of the zinc and consolidates the layer of zinc corrosion products, in order to maintain their protective effect. The thickness of the pore sealant should be sufficient to ensure that this retention takes place, but sufficiently thin for the pore sealant to remain porous, failing which the active species could no longer migrate to the first layer of the coating in order that this first layer plays its part as explained above. Furthermore, too great a thickness of the pore sealant would trap water beneath it and form blisters."
Nothing turns on the detailed parameters of the claim. In substance the invention consists simply in using Zn/Al alloy in place of Zn for buried pipe. The patent tells you this will form a protective layer of corrosion products and that this layer will form on iron "bared at defects" as well as on the iron which remains coated. It also tells you that the upper, pore-sealing layer both slows down Zn corrosion and consolidates the protective layer of Zn corrosion products. It may be noted that the Al does not itself form a corrosion product – its function is to help trap the Zn corrosion product.
Johnsson
This is entitled "Corrosion resistance coatings of Al, Zn and their alloys. Results of 11 years' exposure in soil." It is not well-written – largely one has to try to find out what was done from the tables of results. It is worth noting at the outset that it contemplates "a technical service life of approximately 20 years." This is much too short a period for the skilled man concerned with buried pipes. He wants 50 years as a minimum and often more. So the paper is not one which self-evidently would be of interest to the buried pipe man. The paper's general...
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