“….I would accept that in the case of the coupling the warranty was still continuing up to the date, some three to six months before the accident, when it first became known to the farmer that the handle of the locking mechanism was missing. Up to that time the farmer would have had a right to rely upon the dealers warranty as excusing him from making his own examination of the coupling to see if it were safe…..After it had become apparent to the farmer that the locking mechanism of the coupling was broken, and consequently that it was no longer in the same state as when it was delivered, the only implied warranty which could justify his failure to take the precaution either to get it mended or at least to find out whether it was safe to continue to use it in that condition, would be a warranty that the coupling could continue to be safely used to tow a trailer on a public highway notwithstanding that it was in an obviously damaged state. My Lords, any implication of a warranty in these terms needs only to be stated, to be rejected…..In the state in which the farmer knew the coupling to be at the time of the accident, there was no longer any warranty by the dealers of its continued safety in use on which the farmer was entitled to rely. ……The farmer’s liability arose, not from the defective design of the coupling but from his own negligence in failing, when he knew that the coupling was damaged, to have it repaired or to ascertain if it was still safe to use. The issue of causation, therefore, on which the farmer’s claim against the dealers depended, was whether his negligence resulted directly and naturally, in the ordinary course of events, from the dealers’ breach of warranty. Manifestly it did not.” ii) In the unreported case of Schering Agrochemicals Ltd v Resibel NVSA [1992] CA Transcript 1298, the defendants were employed by the plaintiffs to provide safety devices to guard against the known risk of fire. The safety devices were defectively designed and did not provide that protection. The result, on the 30th September, 1987, was a serious fire. However, on the 8th September, so some three weeks earlier, there had been very small fire, which disclosed to the plaintiffs that the safety device did not work. Both the eminent Judge at first instance (Hobhouse J, as he then was) and the Court of Appeal (Purchas LJ and Nolan and Scott LJJ, as they then were) held that the defendants were not liable in respect of the loss occasioned by the 30th September fire. Their reasons for doing so differed, spanning a break in the chain of causation, a failure to mitigate and remoteness of damage. It is unnecessary to explore those differences of reasoning here. The striking feature of Schering was that the 8th September incident was sufficient to disclose to the plaintiffs that a breach of contract had occurred and made it reasonable to expect the plaintiffs to take appropriate steps to minimise the consequences. A highly dangerous situation had been revealed; the production line ought to have been stopped so that a proper investigation could take place. It may further be noted that, as in Lambert v Lewis (supra), the plaintiffs’ knowledge of the breach and the need to address it took place some period of time before the later incident in respect of which the (bulk of) the damages were claimed. On the facts of the case, viewed as a matter of causation, the plaintiffs’ failure to do what was reasonable “…destroyed the further causative potency of the pre-existing breach of contract…”: Hobhouse LJ, explaining Schering, in County Ltd v Girozentrale(supra), at p.858. Even though the warning on the 8th September had been “purely fortuitous” (Nolan LJ, at p.16 of the Schering transcript), the defendants were entitled to pray it in aid. iii) By contrast with Lambert v Lewis and Schering, the plaintiff in County Ltd v Girozentrale (supra) did not know of the defendant’s breach of contract. This case concerned a share issue. The plaintiff bank agreed to underwrite a placement of the shares; the defendant brokers made representations to potential investors outside and in breach of the terms of the engagement letter; for its part, the bank failed to check on the status of indicative commitments obtained by the chairman of the company. In the event, a significant number of shares were not taken up, leaving the bank with a loss. The Court of Appeal held that the bank was entitled to recover its loss from the brokers. In so doing, the Court of Appeal reversed the decision of the trial Judge who had held, inter alia, that “the brokers’ representations were not of equal efficacy with the bank’s decision to accept the quality of the indicative commitments…without making proper inquiries” (see, the head note, at p.834). Against this background, Hobhouse LJ said this (at p.857 b-d): “ Where a plaintiff does not know of a defendant’s breach of contract and where he is entitled to rely upon the defendant having performed his contract, it will only be in the most exceptional circumstances that conduct of the plaintiff suffices to break the causal relationship between the defendant’s breach and the plaintiff’s loss. The plaintiffs’ conduct was not voluntary in the sense of being undertaken with a knowledge of its significance. Conduct which is undertaken without an appreciation of the existence of the earlier causal factor will normally only suffice to break the causal relationship if the conduct was reckless. It is the character of reckless conduct that it makes the actual state of knowledge of that party immaterial. …”
“ …It seems to me that what will constitute such conduct is so fact-sensitive to the facts of any case where the issue arises that it is almost impossible to generalise. If one must do so, I would say that it must be some unreasonable conduct, not necessarily unforeseeable….., a new cause coming in and disturbing the sequence of events….., not necessarily reckless….., which may result from an accumulation of events which in sum have the effect of removing the negligence sued on as a cause….., which accumulation of events may take place over time….”
“ A plaintiff is under no duty to mitigate his loss, despite the habitual use by the lawyers of the phrase ‘duty to mitigate’. He is completely free to act as he judges to be in his best interests. On the other hand, a defendant is not liable for all loss suffered by the plaintiff in consequence of his so acting. A defendant is only liable for such part of the plaintiff’s loss as is properly to be regarded as caused by the defendant’s breach of duty. As Viscount Haldane, LC, put it in British Westinghouse Electric and Manufacturing Co. Ltd v Underground Electric Railways Co. of London Ltd.,[1912] AC 673 at p.689: ‘The fundamental basis is thus compensation for pecuniary loss naturally flowing from the breach; but this first principle is qualified by a second, which imposes on a plaintiff the duty of taking all reasonable steps to mitigate the loss consequent on the breach, and debars him from claiming any part of the damage which is due to his neglect to take such steps.’ …… Whether a loss is avoidable by reasonable action on the part of the plaintiff is a question of fact not law. This was decided in Payzu Ltd v Saunders[1919] 2 KB 581 .”
“ It is often easy after an emergency has passed to criticise the steps which have been taken to meet it, but such criticism does not come well from those who have themselves created the emergency. The law is satisfied if the party placed in a difficult situation by reason of the breach of a duty owed to him has acted reasonably in the adoption of remedial measures, and he will not be held disentitled to recover the cost of such measures merely because the party in breach can suggest that other measures less burdensome to him might have been taken.”
“ The pH control system in process systems such as that existing at the …plant, is designed to counter organic acids that may form in the furnace outlet stream during normal operating conditions…..The pH control systems are not designed to counteract hydrofluoric acid as this is not an acid that one would expect to encounter in an ethylene plant….”
“ ….this is a slow system so that there is no high priority on this alarm. …we know from experience that we can operate this system for a long period with low pH so there is no need for immediate response….”
“ In our knowledge there was no strong acid. We didn’t know anything about that. We only knew …that the system is constructed for a slow build-up of acid in the process. This is a low capacity ammonia system. It has no big capacity to take care of anything larger than that.”
“ ….that the pH system….was designed and the introduction of ammonia was designed to neutralise acids that have formed from oxygenates that appear in the feed….. Carbonic acid is a weak acid. So we are dealing with a system that has been principally designed to remove CO2 in the form of its weak acid in aqueous solution….. So we have a system designed to remove weak acids….. ….downstream of the heat exchangers and before the compressors ….carbon steel is used and is attacked by weak acids. The reason why the ammonia system is there in the first place is to protect the downstream plant, it is as simple as that. ….the corrosion rate of …[these]…weak acids is very low. So there is no real urgency in adjusting the pH…..”
“ The purpose of the pH system, ……the fact that the pH system was itself a low priority alarm, the fact that it was not designed to deal with contaminants in the feeds such as fluorides, ……the experience of how the plant operates were all accepted by Mr. Lumley as relevant factors when considering Borealis’ response to the pH alarm and drop in pH…. ”
“The pH value must be maintained at 5.5 – 6.5. At a higher pH value emulsion problems may arise in D-1681, and at low PH’s corrosive attacks on the material increase.”
“ ….people do not furnish evidence against themselves simply by adopting a new plan in order to prevent the recurrence of an accident. I think that a proposition to the contrary would be barbarous. ”
“ A pH alarm is present with the LLA set at 5.0. No actions were taken. There was no knowledge at production department or among operators about the potentially damaging effects of hydrofluoric acid on titanium. The alarm was later tested and found to be working. The low pH condition persisted for approximately 59 hours.”
“ Understanding about the potential corrosive effects of low pH, and the need to react to low pH alarm, have to be communicated to all operators.”
“ No actions were taken to increase the pH (e.g., increase NH3). Causal Factor 4 ◦ Historically the unit has run without NH3 with a pH of ~ 4 for extended periods without damage. ◦ In earlier years, the pH meter was unreliable and more emphasis was put on lab sampling of pH. ◦ Lab samples are not routinely taken during the weekend. ◦ …….. ◦ There has been no experience to show that low pH is harmful to titanium. Causal Factor 5”
“ pH trend was noted for the first time” ◦ Historically the unit has run without NH3 with a pH of ~ 4 for extended periods without damage. ◦ In earlier years, the pH meter was unreliable and more emphasis was put on lab sampling of pH. ◦ Lab samples are not routinely taken during the weekend. ◦ …….. ◦ There has been no experience to show that low pH is harmful to titanium. Causal Factor 5”
“….pH is controlled by manually adjusting NH3 injection rates to the tower overhead. The target range for pH is 5.0 and 7.0. Historically the primary purpose for pH control has been to reduce corrosion of carbon steel in the tower overhead, piping and heat exchanger shells. Under normal operating conditions the primary corroding species is carbonic acid formed from a combination of steam condensate and CO2. Since the bundle metallurgy was changed to titanium there have been a number of incidents when NH3 injection has been interrupted and pH levels have been allowed to fall without neutralization, in at least one case for a period of 2-3 weeks. The resulting overhead pH levels have typically fallen to around 4.6. It was determined that the corrosion rate of carbon steel under these conditions is relatively low and, during routine inspections, no visual indication of titanium has been observed as a consequence of intermittent operation below a pH of 5.0. Nevertheless, long term exposure of carbon steel to lower levels of pH has been deemed to be inadvisable. Until this incident, there have been no pH excursions below 5.0 during the past two years. pH is monitored with an on-line pH meter located in the sour water distillate drum (D-1681). When the on-line pH meter was originally installed it was relatively unreliable. Laboratory samples are taken three times a week to verify pH meter readings. Comparison of recent laboratory measures of pH with the on-line meter has shown that the meter currently tracks pH reliably. However, appreciation of this improvement in reliability is not shared by all operators who are responsible for monitoring pH. ”
“ The drop in pH ….began approximately 1 hour after ….[unloading began]…of a shipment of N-butane from the Henning Maersk into the UC731 storage cavern. The cavern inlet from the dock is in close proximity to the unit feed pump suction line. Past experience has shown that the effects of new feed are typically observed in the unit in approximately 1 hour from the time that unloading begins. This observation is viewed as further confirmation that corrosion of the E-1651 and E-1656 is related to contaminants in the butane that was shipped on the Henning Maersk.”
“ 4. No action was taken in response to dropping pH. 5. Experience has never indicated that low pH is potentially damaging to Ti. ”
“ The investigative team interviewed a number of operators and other members of the production staff to gain a better understanding of this oversight. Our objective was to determine the extent to which this could be explained by past operating experience with pH, lack of knowledge and understanding of the potential damaging effects of low pH, or simple failure to follow reasonable standard operating procedures.”
“ ….operating experience for the past 20 years suggested that pH was a relatively unimportant operating parameter. It was certainly true that essentially no one in the production department was aware of the potentially damaging effects of hydrofluoric and/or hydrochloric acid on titanium or even for the potential for HC1 in the primary fractionator tower overhead. This said, it is apparent that the low pH alarm was functional, yet no additional samples were sent to the lab to confirm that the low readings were real. Also, no adjustments were made to NH3 injections which may have mitigated the effects of the HC1.”
“ Root cause category 2a) Lack of knowledge and skills – Historical experience and lack of familiarity of the impact of low pH on the corrosion of titanium, resulted in little or no attention to pH levels below the alarm level. ”
“ The low level pH alarm sounds when the pH in the D1681 distillate drum falls below pH5. When the alarm sounds the alarm indicator light on the panel above the process computer begins to flash. The operator acknowledges the alarm by pressing the flashing light button. Once acknowledged the alarm sound and flashing light will stop. However, the indicator light will stay lit until the pH returns above 5. ”
“ …actual knowledge of the danger to which the defective heat sealer gave rise.”
“ ….the HF cannot be neutralised at the entrance to the [primary] exchanger. It doesn’t matter how much ammonia you put in because it is not going to work if it is unstable. If that is the case you must always have the risk of corrosion at the entrance to the [primary] exchangers…if HF is present.”
“…the meat of this secondary case….as the evidence has turned out, is not so much in relation to the costs of the physical repairs….”
“ …..there is no reason to conclude that there were any holes in the heat exchanger tubes any significant time before the gas alarm was triggered. If the feeds had been changed before there were holes in the tubes, the probability …..is that production would have continued – using perfectly acceptable uncontaminated feeds which would cause no further damage to the tubes – for the balance of September….. …….. If they were not leaking ….there would have been no reason to stop.”
“ To suggest that the probable consequence of discovering that your plant has been subjected to a strong acid for 22 plus hours and to then continue at full production ignoring that fact, not even looking at your equipment to discover the level of damage….we say cannot possibly be the probable consequence of ceasing to use the LPG shortly before the perforations occur. One could imagine the scenario in which Borealis were to conduct itself like that and what would be said if two weeks later there was suddenly a major incident arising out of the fact that these pipes have simply been allowed to stay in situ with nobody doing anything about it.”
“ ….during the early part of January, they should have been looking at availabilities of butane to blend with what they could be fairly certain was going to be some heel left there. So by the time they were getting close to completion of lifting of the cargo to Statoil, they should have been close to purchasing a cargo of butane to blend in with what would have been left in the cavern….. ….. ….they would have to wait until they knew what the heel was before they could finally make the purchase, but they could still be determining what cargoes were available prior to that….. ”
“…they were slow, they could have been quicker.”
“ No, I wouldn’t say it was unreasonable.”
“ Now I think a Court of Justice ought to be very slow in countenancing any attempt by a wrong-doer to make captious objections to the methods by which those whom he has injured have sought to repair the injury. When a road is let down or land let down, those entitled to have it repaired find themselves saddled with a business which they did not seek, and for which they are not to blame. Errors of judgment may be committed in this as in other affairs of life. It would be intolerable if persons so situated could be called to account by the wrong-doer in a minute scrutiny of the expense, as though they were his agents, for any mistake or miscalculation, provided they act honestly and reasonably. In judging whether they have acted reasonably, I think a Court should be very indulgent and always bear in mind who was to blame.”
“ I consider that the authorities establish the following propositions. (a) The fact and, if so, the extent of the diversion of staff time have to be properly established and, if in that regard evidence which it would have been reasonable for the claimant to adduce is not adduced, he is at risk of a finding that they have not been established. (b) The claimant also has to establish that the diversion caused significant disruption to its business. (c) Even though it may well be that strictly the claim should be cast in terms of a loss of revenue attributable to the diversion of staff time, nevertheless in the ordinary case, and unless the defendant can establish the contrary, it is reasonable for the court to infer from the disruption that, had their time not been thus diverted, staff would have applied to activities which would, directly or indirectly, have generated revenue for the claimant in an amount at least equal to the costs of employing them during that time.”
“ The learned registrar has allowed nothing for either of these items. I think it is clear that something must be allowed. What the figure may be is a matter for him to decide, but I do not think it can be right to say that the Admiralty have suffered no loss by giving up their dry dock and by using their cranes in doing these repairs. The Nelson occupied the dock to the exclusion of other ships, and made use of the cranes and so on for the purpose of docking and cleaning and coating the bottom, which would be necessary in connection with these repairs. Docks and cranes cannot be used without expense, and there must be some damage to the Admiralty from these matters. The learned registrar says that in respect of these there was not a pecuniary expenditure or loss and, therefore, these items are not allowable. I think that is wrong. I think there was pecuniary expenditure and loss. It may not be actual money paid out to any particular person, but these expensive appliances cannot be utilised without some loss.”
“ ….we had two parallel maintenance works going on at the site….both would have resulted …[in]…a production loss alone but since they were carried out in parallel the production loss that resulted was clearly less than in the case they would have been done at a different time individually.”