OSHRC Docket No. 13591

Occupational Safety and Health Review Commission

September 30, 1982


Before ROWLAND, Chairman; CLEARY and COTTINE, Commissioners.


Office of the Solicitor, USDOL

Albert H. Ross, Regional Solicitor, USDOL

Edward J. Dempsey, for the employer




This case has been remanded to us by the United States Court of Appeals for the Second Circuit. Pratt & Whitney Aircraft v. Secretary of Labor, 649 F.2d 96 (2d Cir. 1981). The court reviewed our decision in Pratt & Whitney Aircraft, Division of United Technologies Corp., 80 OSAHRC 38/A2, 8 BNA OSHC 1329, 1980 CCH OSHD P24,447 (No. 13591, 1980) and, inter alia, after vacating our action affirming both the alleged violation of 29 C.F.R. 1910.94(d)(7)(iii) in the serious citation and one of the two alleged violations of 29 C.F.R. 1910.132(a) in the nonserious citation, remanded for further proceedings consistent with its opinion on those two items. We have examined the briefs of the parties on remand and carefully reevaluated the record. We conclude that the section 1910.94(d)(7)(iii) allegation should be affirmed under the "significant risk" test adopted by the court. We vacate the section 1910.132(a) allegation on the Secretary's motion to withdraw the item. [*2]


The section 1910.94(d)(7)(iii) n1 allegation concerns Pratt & Whitney's ("P & W's") ventilation practices in its plating department. Its seven plating lines contained tanks of both cyanides and acids; one line also contained tanks of hydrogen peroxide, glacial acetic acid, and heated slushing oil. Each tank in each line had a separate exhaust duct, but those ducts merged into a common duct for each line, from which all the chemical exhausts from the line were vented through a stack in the roof. The Secretary alleged that the use of a common duct to ventilate both acid mists and cyanide mists in each line, and the use of a common exhaust duct in one line to ventilate the tanks of hydrogen peroxide, glacial acetic acid, and heated slushing oil constituted noncompliance with the cited standard. Acid mists and cyanide mists used in the plating processes, the Secretary alleged, are exhausted into the common duct system where they can combine into hydrogen cyanide gas ("HCN"), a highly poisonous and explosive substance. Also, the Secretary contends, when hydrogen peroxide and heated slushing oil are mixed there is a possibility of explosion, and the mixture of hydrogen peroxide [*3] and acetic acid results in potentially explosive peracetic acid.

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n1 Section 1910.94(d)(7)(iii) provides in pertinent part:

1910.94 Ventilation

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(d) Open surface tanks --

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(7) System Design.

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(iii) Two or more operations shall not be connected to the same exhaust system where either one or the combination of the substances removed may constitute a fire, explosion, or chemical reaction hazard in the duct system. Traps or other devices shall be provided to insure that condensate in ducts does not drain back into any tank.

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Judge Abraham Gold vacated the section 1910.94(d)(7)(iii) allegation for failure of proof. He ruled that the Secretary's evidence does not demonstrate the existence of hydrogen cyanide gas or peracetic acid in the common duct system, and that it does not demonstrate hydrogen peroxide and slushing oil combine in the common duct. The judge stated:

The Secretary has presented textbook theory, without obtaining redily available information which would show whether [*4] there existed at Respondent's facility those specific conditions required for the creation of a fire, explosion, or chemical reaction hazard. He has offered nothing more than conjecture. In addition, he suggests that a hazard might arise . . . by virtue of a ventilation breakdown, malfunction of the heating systems for the various solutions, spontaneous combustion caused by an employee's smoking, heat caused by mechanical failure, a down-draft of effluent or "by some yet unimagined happening." We have no showing of any reasonable likelihood of such mishaps; the Secretary might just as well have suggested the possibilities of arson or insurrection.


The Commission reversed Judge Gold and affirmed the citation item. The Commission concluded that the use of the word "may" in the cited standard requires a violation to be found whenever a hazardous combination of substances in a duct system is possible. The Commission held that it is not necessary for the Secretary to prove that a chemical reaction was reasonably likely or that the prohibited hazards actually threatened employees at the time of inspection. The Commission further found, however, that the Secretary's proof demonstrated [*5] the "realistic possibility" that hazardous HCN gas could be formed and that fire or explosions could result from a reaction in the duct of heated oil and either hydrogen peroxide or peracetic acid.


The Second Circuit, citing the U.S. Supreme Court's decision in Industrial Union Department, AFL-CIO v. American Petroleum Institute, 448 U.S. 607, 100 S.Ct. 2844, 2864-66 (1980) ("the Benzene Case"), held that section 1910.94(d)(7)(iii) can properly be interpreted as proscribing an employer's use of a common exhaust system only where there exists a "significant risk," not a mere possibility, that a combination of the substances removed will cause a fire, explosion, or chemical reaction hazard. Although the court acknowledged that the Commission had also used the term "realistic possibility" in setting out its findings, the court found Commission use of those terms ambiguous and therefore vacated and remanded, stating:

The OSHRC on remand may conclude that the risk of an explosion, fire, or chemical reaction hazard in Pratt & Whitney's ductwork was, indeed, significant. This decision is best left to the OSHRC in the first instance. It is the agency, not the courts, that possesses [*6] the required expertise to make such decisions. . . .

The court further stated, however, that it was

. . . compelled to point out . . . that implicit in the opinion of the ALJ is a determination that the Secretary failed to establish even the remotest possibility of such mishaps occurring.

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. . . while the OSHRC is not bound to accept the factual findings of the ALJ, the latter's determinations are entitled to some weight and should not be disturbed without explanation.

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In arriving at its determination that the ductwork of petitioner's plant posed a possibility that a hazardous event might occur, the OSHRC relied upon the "textbook theory" rejected by Judge Gold. Additionally, the OSHRC noted that the Secretary's expert, Mr. Padden, had not recalled seeing similar ductwork in the "100 or so" other plating departments he had visited. The latter testimony, however, conflicted with that of petitioner's expert, Mr. Doyle, . . .

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Furthermore, petitioner conducted scientific tests which revealed not a trace of the dangerous substances that the Secretary claimed might form. On remand, the OSHRC is obligated to weigh carefully all of the latter evidence in determining [*7] whether the Secretary has demonstrated by a preponderance of the evidence that the common ductwork at petitioner's plant violated 1910.94(d)(7)(iii). Again, we express no view as to the proper outcome of this reconsideration: our concern is rather to assure that all the evidence is given appropriate weight and that the conclusion reached is adequately supported by a reasoned explanation.

The Commission invited the parties to file briefs on remand and both parties did so. Their arguments on remand are, for the most part, those made earlier when this case first came before us for decision. The Secretary argues that the record shows the hazard created by P & W's common duct system was the "probable formation" of deadly poisonous hydrogen cyanide gas. The gas could be hazardous to employees working on the roof where the gas was emitted, the Secretary contends, and to plating department employees should down-drafts return gas to the plant floor. The gas in the ducts, the Secretary asserts, presented a fire or explosion hazard. Finally, the Secretary reasserts that the record establishes that the combination of hydrogen peroxide and heated oil, and the combination of hydrogen peroxide [*8] and acetic acid presented fire and explosion hazards.

The Secretary also contends that the Second Circuit should not have applied the significant risk concept to this case. He argues that the Supreme Court in the Benzene Case, supra, specifically limited the requirement for a finding of significant risk to "permanent" standards promulgated under section 6(b) of the Occupational Safety and Health Act ("the Act"), as opposed to those standards, like the one involved here, which were promulgated under section 6(a) of the Act. n2 This view is supported, the Secretary asserts, by the Seventh Circuit Court of Appeals in Super Excavators, Inc. v. OSHRC, 674 F.2d 592 (7th Cir. 1981), cert. denied, 102 S.Ct. 2958 (June 21, 1982). n3 With the significant risk concept read out of the case, the Secretary argues, any possible vagueness in the cited standard could be cured by the application of the "reasonable person" test to the interpretation of the standard, i.e., the standard would be read to require that a reasonable person perceive a hazard under the circumstances of the case.

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n2 Section 6(a) of the Act authorized the Secretary of Labor to adopt as an occupational safety or health standard any national consensus standard or any established federal standard without the necessity of complying with the procedural requirements of the Administrative Procedure Act ("APA"), 5 U.S.C. 551-559, 701-706 (1977). The procedural requirements thus omitted include: publication in the Federal Register of notice of proposed rulemaking, opportunity for interested persons to express their views on the proposed rule, a statement in the rule of its basis and purpose, and publication in the Federal Register of the rule as adopted. The Secretary's authority to adopt standards without adhering to these procedural requirements expired two years after the effective date of the Act. In order to promulgate any standard after that period, the Secretary must comply wth the procedural rulemaking requirements contained in the APA and section 6(b) of the Act, 29 U.S.C. 655(b), which include, among other things, notice of proposed rulemaking and opportunity for interested persons to comment.

n3 We point out to the Secretary that we must comply with the Second Circuit's order to use significant risk in this case on remand because the Second Circuit's decision constitutes the law of the case. See Briggs v. Pennsylvania R.R., 334 U.S. 304, 306 (1948). Furthermore, the Commission is required to comply with remand orders of the courts of appeals. Butler Lime and Cement Co. v. OSHRC, 685 F.2d 544 (7th Cir. 1981); Frank Irey, Jr., Inc., 77 OSAHRC 192/F11, 5 BNA OSHC 2031, 1977-78 CCH OSHD P22,283 (No. 701, 1977).


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P & W argues that all the Secretary offered to show was that if acid mists of certain concentrations were to mix with cyanide mists of certain concentrations in the common duct, HCN would evolve; and that if hydrogen peroxide mists of certain concentrations were to mix with heated slushing oil in the common duct at a certain temperature, there would be a fire or explosion potential; and that if peracetic acid mists of certain concentrations formed by the combination of hydrogen peroxide and glacial acetic acid were to combine with heated slushing oil in the common duct at a certain temperature, there would be a fire or explosion potential. P & W asserts that the Secretary utterly failed to prove the factual predicates which support the premises leading to his conclusions. P & W's testing, however, demonstrated that there was no HCN hazard because HCN was not present in the common duct, that the air velocity over the tanks containing oil and hydrogen peroxide resulted in duct temperatures too low to create fire or explosion hazards, and that slushing oil was not entering the common duct to create a [*10] fire or explosion hazard.


Our consideration of this case on remand is governed by the instructions of the Second Circuit as quoted above. We interpret the cited standard at section 1910.94(d)(7)(iii), when applied under the "significant-risk" test to encompass the protection of employees from fire, explosion or chemical reaction hazards that are unusual or infrequent. Thus, the absence of proof of the actual existence of hazardous chemical combinations in P & W's common duct system does not conclusively establish that P & W's employees were not exposed to a significant risk of harm.

The Secretary contends that acid mists and cyanide mists from the tanks in P & W's plating department could combine in its common duct to form deadly HCN gas, which poses a fire and explosion hazard because of its low flash point (0 degrees F.). The Secretary also contends that, because HCN is poisonous, the gas could be hazardous to employees working on the roof of the plant should it be vented through the roof stacks, and to employees in the plant itself should a down-draft return the gas to the plating department.

Mr. Padden, the Secretary's expert witness, testified that if the surfaces of [*11] the acid or cyanide solutions were agitated by the immersion or retrieval of a part dipped into those solutions "mists and small gobblets [sic] would be readily drawn up into the main trunk line [of the common duct]" because of the about 200 feet per minute velocity of the air in the ventilation system blowing across those tanks. The solutions were heated and testimony indicated that heated solutions gave off more easily-transported mists and vapors than did cold solutions. n4 Dunstan, P & W's industrial hygienist, acknowledged that it is not good practice to vent cyanide and acid mists through a common duct and that it can lead to HCN formation and fire and explosion hazards. P & W's expert witness, Mr. Doyle, acknowledged that cyanide mists could be drawn into the ductwork in the case of highly agitated solutions. Since parts were constantly being immersed into the solutions, we find that the solutions could become sufficiently agitated that cyanide mists could be drawn into the ductwork, react with the acid mists and vapors that were undisputedly already there, and form HCN.

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n4 The acid tanks in the plating department ranged in temperature from room temperature to 120 degrees F.; the cyanide tank temperatures went from room temperature to about 150 degrees F. If the steam valves malfunctioned, as they had on occasion, the temperatures of the acids and cyanides could go up even higher. If the temperatures exceeded the boiling point, larger globules of the particular solutions would be carried into the common duct, thereby increasing the potential for HCN formation.


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Doyle's conclusion that there was not a hazard of HCN formation must be deemed modified by his acknowledgment that cyanide mists could be drawn into the ductwork in the case of highly agitated solutions. The fact that P & W's testing did not disclose the presence of any HCN gas in the common duct does not rebut this finding. P & W's evidence shows only that HCN was not present when the tests were made. It does not show that the conditions necessary for HCN formation would not arise.

If a down-draft occurred, HCN already formed in the common ducts could be swept back into the plant. The record shows that down-drafts could occur if P & W's ventilation system broke down, such as by a malfunctioning of the belts in the system. It is undisputed that ventilation system breakdowns had occurred in P & W's plant, and that one such breakdown had even occurred during the inspection of the plant. Belts in the system had broken. Further, the ventilation system in the plating department itself had broken down. These hazards were heightened by the fact that P & W had not provided for an alarm system to warn [*13] its employees of breakdowns in the ventilation system. Witness Champney, an employee in the plating department when the breakdown there occurred, described how he had become aware of the breakdown: "You started to smell and choke a little bit, and you realized that you were smelling acid." Because HCN gas is one of the most potent of poisons, employees were therefore subjected to the hazard of being poisoned due to down-drafts occurring after ventilation system breakdowns.

The evidence also indicates that in the event of a down-draft acid mists could flow from the common duct down through the separate cyanide ducts, combine there with cyanide mists and enter the plating department. Thus, employees could be exposed to HCN formation due to a down-draft even if no cyanide mists had entered the common duct. We conclude that the Secretary has therefore proven that there was a significant risk of HCN poisoning from ventilation system breakdowns and resultant down-drafts.

The Secretary also contends, with respect to one of P & W's plating lines, that hydrogen peroxide and heated slushing oil could combine in the common duct to cause a fire or explosion. He alleges further that hydrogen [*14] peroxide and acetic acid, both of which were contained in one of the line's tanks, could combine to form peracetic acid; peracetic acid could combine with oil mists in the common duct and create fire and explosion hazards.

P & W's industrial hygienist, Dunstan, admitted that hydrogen peroxide and heated slushing oil entered the common ductwork. He conceded that there was a high hazard of an instantaneous explosion if the two chemicals were mixed. He further testified that peracetic acid was an explosive chemical formed by the mixing of hydrogen peroxide and acetic acid. He acknowledged that it is not good practice to vent the various chemicals in this line through common ducts and that it can result in fire and explosion hazards. Mr. Larsen, an industrial hygienist who testified for the Secretary and inspected P & W's plant, stated that peracetic acid is an extreme oxidizing agent which should be kept away from organic materials and that exhausting peracetic acid and heated oil through the same duct presented fire and explosion hazards.

Padden, testifying for the Secretary, explained that if P & W's ventilation system failed, and the production of heated slushing oil and hydrogen [*15] peroxide continued, small globules of oil and chemicals would be emitted from the plating line tanks which could be drawn through the exhaust system into the common duct and cause a chemical reaction. When Padden was asked about the effect of a failure of P & W's ventilation system on the mixture of peracetic acid and slushing oil mists, he testified that the two substances would meet without diffusion. These reactions could result even if a down-draft did not occur. As noted above, the Secretary's industrial hygienist, Larsen, had testified earlier that exhausting peracetic acid and heated oil through the same duct presented fire and explosion hazards. Mr. Dupre, P & W's safety engineer, testified that a fire had previously occurred in P & W's ductwork. n5 Consequently, in light of the above testimony and particularly in light of the abundant testimony from both the Secretary's and P & W's witnesses about failures in P & W's ventilation system, we find that the Secretary has proven there was a significant risk of fire and explosion in P & W's common duct system as a result of a combination of the aforementioned substances.

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n5 This fire was attributed to careless smoking. However, ignition sources were not eliminated in the plating department. One employee testified that he smoked there and never had been instructed against it. Thus, there was a demonstrated possibility of ignition of the flammable or combustible mists and vapors by cigarette sparks.

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The Court has asked us to consider two other matters: (1) the Court points to an apparent conflict in the testimony of Padden and Doyle with respect to the type of ductwork most commonly used in the ventilation systems of other industrial plating departments; and (2) the Court points out that P & W's scientific testing did not reveal any trace of the dangerous substances the Secretary claimed might form.

Regarding industry ventilation practices, Padden testified that it was not the practice in any of the plants he visited to use separate exhaust ducts flowing into a common duct. In over 400 or 500 visits to 100 or so plants with plating departments in the United States, Padden could not recall any departments that vented acids and cyanides [*17] into a common duct. He testified that it was "a very unsafe practice to use a common duct on any type of material that could cause fire or an explosion."

Doyle testified that he had visited "possibly fifteen or twenty plants" that used plating lines similar to P & W's and that some had individual ducts and others had common ducts. However, when asked if he recalled those plants with common ducts, Doyle named one plant that he thought had common ductwork, one that used both kinds of ductwork, and one that he believed had used common ductwork but that he had not visited since the late 1940's. On the basis of Padden's testimony, which we find substantially more compelling, we conclude that the usual practice in the industry was to use individual ductwork. This is hardly surprising in light of the testimony of P & W's own industrial hygienist, Dunstan, noted above, that it was not good practice to vent the chemicals used in P & W's plating lines through a common duct because the incompatible chemicals could mix, generate HCN, and cause a fire or explosion. n6

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n6 Dunstan specifically testified on direct examination by the Secretary as follows:

Q: Now, did you have any conversations with Mr. Larsen [OSHA's compliance officer] about the common ductwork used for the various chemicals that we have just discussed?

A: There may have been.

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Q: Did you express any opinion as to whether or not these chemicals should be carried out through a common duct?

A: I may have.

Q: And what would that opinion be?

A: That it would not be good practice.

Q: Why wouldn't it be good practice?

A: Because of intermixing of incompatible materials.

Q: The intermixing of incompatible materials?

A: Yes, sir.

Q: It can cause what?

A: Hydrogen cyanide generation.

Q: Could it also cause a fire hazard?

A: Could be.

Q: Could it also cause an explosion hazard?

A: Could be.

Larsen testified that he asked Dunstan during the inspection why all the plating lines vented into a common ductwork, and "he just shook his head and he said, well, it was a matter of economics. He further stated that this was a poor excuse, but what can I say."


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With respect to the testing issue, the fact that the Secretary did not test scientifically for the presence of the allegedly hazardous combinations of substances and that P & W did so and did not detect any such combinations does not invalidate the Secretary's case. The Secretary's case is not premised on the normal occurrence of hazardous combinations. The standard requires no such proof. The standard's purpose is preventative and its protection extends to unusual conditions and infrequent occurrences. Interpreted with the significant risk requirement mandated by the Second Circuit, the standard requires that the Secretary prove that either one or a combination of the substances removed through P & W's common duct system presented a significant risk of a fire, explosion, or chemical reaction hazard in that ductwork. The evidence discussed above and in our earlier decision convinces us that the Secretary has discharged his burden of proof under the standard.

The Secretary proved that there was a significant risk that unusual conditions would indeed occur. That such conditions were only likely [*19] to occur infrequently does not provide any reasonable basis for the administrative law judge to suggest that the possibility of their occurrence was so minimal "that the Secretary might just as well have suggested the possibilities of arson or insurrection." Nor does it preclude a finding of noncompliance with the standard under the significant risk test, nor, more importantly, does it diminish the need to prevent such occurrences. The hazardous substances involved here could combine to quickly, perhaps with virtually no warning, bring death or serious physical harm to P & W's employees. It is our conclusion that the cited standard was drafted to prevent such eventualities; interpreting it to require proof of the actual existence of hazardous chemical combinations in the duct system undermines the standard's preventative purpose and essentially means that a showing of noncompliance with the standard's terms would have to await employee injuries from hazardous chemical combinations.

We have given due weight to the judge's conclusions. However, we find that the evidence that the usual industry practice is to use separate exhaust ducts for the chemicals involved here, the acknowledgment [*20] by P & W's industrial hygienist that common ductwork is not good practice and can result in HCN formation as well as fire and explosion hazards, and the testimony of the Secretary's expert outweigh those conclusions.

Accordingly, we reaffirm our earlier decision on the Secretary's section 1910.94(d)(7)(iii) allegation. We also grant the Secretary's motion to withdraw the section 1910.132(a) allegation concerning the failure of the employee operating the "spider" mechanism to wear a hardhat.




ROWLAND, Chairman, dissenting:

I dissent from the majority's opinion finding that the Secretary proved noncompliance with section 1910.94(d)(7)(iii) under the "significant risk" test required by the Second Circuit. Despite the majority's claim that it is deciding this case in accordance with the terms of the court's remand order, it in reality applies the test rejected by the court, that the likelihood of occurrence of a hazard be merely possible as opposed to significant. As the court specifically stated, "[t]he occurrence of a freakish event constitutes a possibility, but we believe . . . that safety standards may not be so broadly interpreted so as to embrace such slight [*21] risks of harm." Pratt & Whitney Aircraft v. Secretary of Labor, 649 F.2d 96, 104 (2d Cir. 1981). Yet in affirming the citation allegation in issue, the majority reasons that the standard applies to "unusual conditions" and "infrequent occurrences," thereby adopting the broad interpretation which the court has expressly disavowed. Furthermore, despite the court's admonition that the Commission evaluate all of the evidence of record, the majority has not given proper consideration to the evidence submitted by P & W in rebuttal to the Secretary's case.

With respect to the Secretary's contention that acid mists and cyanide mists could combine in the common duct to form hydrogen cyanide ("HCN") gas, the majority cites the testimony of the Secretary's expert witness, Padden, who stated that chemical mists would be drawn into the ductwork if the surfaces of the acid or cyanide solutions were agitated. The majority also notes P & W expert witness Doyle's statement that cyanide mists could enter the ductwork if the cyanide solutions were highly agitated. As the majority itself concedes, however, this evidence shows nothing more than a possibility that acids and cyanides could enter [*22] the common duct. The majority states, "[w]e find that the solutions could become sufficiently agitated that cyanide mists could be drawn into the ductwork. . . ." (emphasis added). Furthermore, the record does not contain any evidence about the extent to which the surfaces of the acid and cyanide solutions were agitated during actual plant operations, nor does the evidence show any appreciable likelihood of HCN being formed as a result of agitation of the surfaces of the acid or cyanide solutions. Indeed, P & W's expert, Doyle, testified from personal experience that the cyanide solutions in the tanks only released water vapor and an ammonium compound into the air to be carried into the ductwork above the cyanide tanks. He further testified that any combination of ammonia with acid would produce only a white salt. n1 Therefore, Doyle concluded that the plating lines did not present a chemical reaction, fire, or explosion hazard. The opinions of highly qualified witnesses who testify from personal experience are entitled to substantial weight. n2 Kelly Springfield Tire Co., OSAHRC Docket No. 78-4555 (Aug. 27, 1982) (dissenting opinion).

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n1 Dunstan gave similar testimony. See note 3 infra.

n2 Doyle had about twenty years of experience as a chemical engineer, with extensive experience in industrial abatement of chemical hazards. Although the Secretary's expert, Padden, had comparable experience, he did not dispute Doyle's testimony regarding the chemical reactions resulting from the cyanide tanks.

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Moreover, the results of P & W's testing for HCN corroborate Doyle's opinion. Contrary to the majority, those tests results are entitled to weight. There is no evidence from which to conclude that P & W's tests were not taken under conditions representative of actual plant conditions. n3 See Snyder Well Servicing, Inc., 82 OSAHRC 10/C5, 10 BNA OSHC 1371, 1982 CCH OSHD P25,943 (No. 77-1334, 1982) (concurring and dissenting opinion). As I have previously stated, the burden is on the Secretary to prove by a preponderance of the evidence that there was a significant risk of HCN formation. P & W is not required to prove that there is no such risk.

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n3 The majority contends that breakdowns in the ventilation system were normal occurrences in P & W's plant and that such breakdowns could create down-drafts, forcing HCN present in the ductwork back down into the plant. However, the record does not demonstrate that ventilation system defects brought about the formation of HCN in the first place. The testimony of employee Champney, cited by the majority, shows only that acid fumes, not HCN, were released into the air when the ventilation system broke down in the plating department. Furthermore, Dunstan, P & W's industrial hygienist to whom breakdowns in the system were reported, stated that in the event of breakdowns, ammonia vapor released from the cyanide tanks generally would mix with vapors from the acid tanks, thus forming ammonia compounds.

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The majority opinion also asserts that the likelihood of entry of mists into the common ductwork increases as the temperatures of the solutions in the tanks increases. However, other than a reference to the boiling point of the substances [*25] in the tanks, which itself is based on an unsupported assumption that the boiling point could be reached, n4 Padden's testimony about the magnitude of the solutions' temperatures in relation to the increased hazard of HCN formation is nonspecific and conclusory. It is speculative to conclude from his testimony that a significant risk of hazard results from the temperatures to which the tanks were heated.

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n4 Padden testified that he did not know how much steam was available to the tanks. He could not, therefore, testify whether the steam available was capable of bringing the solutions to boiling. Also, the record does not show that the boiling points of the solutions in the tanks had ever been exceeded.

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The majority also concludes that the Secretary proved hydrogen peroxide and heated slushing oil could combine in the common duct to cause a fire or explosion and that hydrogen peroxide and acetic acid could combine to form peracetic acid, which could then combine with oil mists in the common duct to create fire and [*26] explosion hazards. I disagree.

Even assuming, as the majority states, that P & W's industrial hygienist Dunstan conceded that hydrogen peroxide and oil entered the common duct, n5 Dunstan did not state that the mixing of hydrogen peroxide and heated oil would therefore occur. Rather, his testimony was to the contrary. Dunstan stated that there were two tanks of cyanide solution between the hydrogen peroxide and the oil tanks and that as the hydrogen peroxide moved through the common duct it would be decomposed to water by the cyanides before it could even reach any oil. In fact, Dunstan further stated that he tested for the presence of oil in the ductwork and found only a dry residue, indicating that oil was not present in the ductwork. Dunstan also testified that a reaction between hydroogen peroxide and slushing oil would require a temperature of about 390 degrees F. The temperature of the oil, however, was no more than about 300 degrees F., while the hydrogen peroxide was not heated. According to Dunstan, he measured the temperature of the air entering the duct from the oil tank at about 85 degrees F. Based on a measured air flow of about 6000 cubic feet per minute, Dunstan [*27] estimated the temperature inside the duct to be only about 90 degrees F. He concluded, therefore, that heated oil and hydrogen peroxide did not present a hazard.

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n5 The only testimony which might support the majority's assertion that Dunstan had so conceded is found in the following answers given by Dunstan upon questioning by the Secretary's attorney:

Q: Now, do you use hydrogen peroxide in the Plating Department?

A: Yes, Sir.

Q: Do you use heated oil?

A: Yes, sir.

Q: Do they go up a common duct?

A: Yes, sir.

The Secretary's attorney never specifically asked Dunstan if hydrogen peroxide and oil did in fact enter the common duct. In view of the generalized nature of the Secretary's questions and Dunstan's answers, this testimony shows nothing more than the fact that a part of the ventilation system included a common duct. As noted in the text of this opinion, when Dunstan did specifically address the question of whether oil entered the common duct, he testified that oil was not present in the common duct.

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The Secretary did not rebut Dunstan's testimony. Indeed, the Secretary's own expert witness, Padden, admitted on rebuttal that he did not actually know if hydrogen peroxide or slushing oil entered the common duct. Padden also admitted that a knowledge of the velocities of the exhaust system would have been helpful to him in arriving at his opinion on the likelihood of the occurrence of hazardous chemical reactions. Yet, neither Padden nor the Secretary's industrial hygienist, Larsen, measured the air flow into the duct system. n6

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n6 The record does not show any basis for Padden's reference to an exhaust velocity, noted in the opinion of the majority, of 200 feet per minute.

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The majority opinion also finds that the Secretary proved his allegation of hazards stemming from the formation of peracetic acid. Dunstan, however, testified that a temperature between 140 degrees-180 degrees F. is required for the formation of peracetic acid and that it takes some period of time before any appreciable amount of the acid [*29] can be developed. Although Larsen claimed that heat was not required to produce peracetic acid, he did concede, as did Padden, that peracetic acid did not present an explosion hazard unless it was heated to 230 degrees F.; Padden stated that the flash point of peracetic acid is 105 degrees F. Yet, as previously noted, Dunstan estimated the duct temperature to be only at about 90 degrees F. Larsen admitted that he had made no determination regarding the temperature in the ducts.

Nevertheless, the majority states that a source of ignition for the chemical substances in the plating department existed from cigarette smoking. The employee on whom the majority relies, however, did not testify that he smoked in the vicinity of the tanks. In fact, the employee testified that he had been instructed against smoking in one particular area of the department. DuPre, P & W's safety engineer, testified that smoking was prohibited at certain tank locations. Also, the fire caused by smoking to which the majority refers occurred about ten years before the hearing of this case. There is absolutely no evidence that any fire had occurred more recently than that.

Accordingly, I conclude the judge [*30] properly determined that only a remote possibility of a fire, explosion, or chemical reaction hazard was demonstrated by the Secretary. Since such proof does not establish the "significant risk" required by the court, I would affirm the judge's decision vacating the pertinent citation item. n7

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n7 In view of my conclusion that the Secretary failed to demonstrate the existence of a significant risk of hazard, I do not reach the question of whether individual or common ductwork was the practice in the industry. See Kansas City Power & Light Co., 82 OSAHRC 13/A2, 10 BNA OSHC 1417, 1982 CCH OSHD P25,957 (No. 76-5255, 1982) (dissenting opinion). Therefore, I need not consider whether the majority's conclusion that the industry customarily uses separate ductwork is supported by the evidence.

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