gas mains from corrosion and to inspect its mains periodically to insure that the mains continue to be protected adequately.
On December 18, 1973, natural gas seeped into the drive-in branch of the Marine Bank located on West 38th Street between Liberty and Poplar Streets in Erie, Pennsylvania. The gas exploded and injured the plaintiff, Lou Ann Karle, who worked as a bank teller at the drive-in branch. The gas escaped from a 20" distribution main running underneath West 38th Street, and seeped into the bank through a telephone conduit. The defendant, the National Fuel Gas Distribution Company (hereinafter, "NFG"), operated and maintained the distribution main since its installation in 1950.
To recover for the personal injuries, the plaintiffs Lou Ann Karle and her husband Michael sued NFG in this court, claiming diversity jurisdiction. The Karles contend that NFG failed to protect adequately its 38th Street main from corrosion and failed to inspect the main regularly to insure that the main was not leaking. In addition, the Karles assert that NFG is liable under theories of strict liability and negligence per se as the result of the gas company's violation of federal regulations on corrosion control.
The deteriorating effect of underground electrical currents on underground metal pipe, called corrosion, is at the heart of this lawsuit. Corrosion occurs when an underground electrical current leaves the pipe and re-enters the surrounding soil. The pipe corrodes at the point of the current's departure. The more susceptible a particular soil is to the passage of electrical current, or the lower its "resistivity",
the more likely it is that pipes buried in that soil will corrode.
To prevent the corrosion of underground pipes, utility companies commonly use a procedure known as "cathodic protection." Cathodic protection seeks to prevent electrical currents from passing from the pipe to the soil by directing a stronger current onto the surface of the pipe which, essentially, overpowers and negates any current which would otherwise leave the pipe and corrode the pipe at that point.
Utility companies generally select one of two methods of cathodic protection to prevent corrosion -- impressed current and galvanic. The impressed current method achieves cathodic protection by attaching an external source of direct current directly to the pipeline. The galvanic method involves attaching to the pipeline anodes made of zinc or magnesium -- metals more electrically active than the metal of the pipeline. The interaction of dissimilar metals in the medium of an electrically resistant soil creates a flow of electricity from the anode to the pipeline. As a result of this interaction, the metal of the anode corrodes. These anodes are sometimes called "sacrificial anodes" because the metal of the anode corrodes instead of the metal of the pipeline. The electrical flow from the anode to the pipeline, like the flow from the battery to the pipeline in the impressed current method, overpowers any electrical current which would otherwise leave the pipe and corrode it in the vicinity of the anode. The effectiveness of the anode in reducing corrosion is greatest in the immediate area of the anode, and diminishes progressively further away from the anode. Accordingly, to protect a pipeline from corrosion over a distance of hundreds of feet, many anodes are generally required.
Electrical potential measures the facility with which electricity can leave a pipeline at various points, and it is possible to measure the likelihood that a particular section of pipe will corrode by calculating the electrical potential of the pipeline at various points. Electrical potential is measured in millivolts (mv.) by conducting pipe to soil potential surveys.
The same pipeline may have different potentials if the soil is different at one point than at another. Generally, the higher a pipeline's electrical potential, the more difficult it is for electricity to leave the pipeline and hence, the less likely it is that the pipeline will corrode. Most authorities agree that a pipe to soil potential of 850 mv. indicates relatively little likelihood of corrosion.
Because the installation of cathodic protection should increase a pipeline's potential, one may determine whether a pipeline is adequately protected by comparing pipe to soil measurements taken before and after the installation of cathodic protection.
II. FINDINGS OF FACT
Lou Ann and Michael Karle are residents of Pennsylvania, and NFG is incorporated in New York. The Court has jurisdiction over this lawsuit, in which the amount in controversy exceeds $10,000, on the grounds of diversity of citizenship, 28 U.S.C. § 1332(a) . Pennsylvania law applies.
NFG installed the 20" pipeline which runs underneath West 38th Street in the City of Erie, Pennsylvania in 1950. The pipeline is called a distribution main as opposed to a service main. It carries gas at a pressure of 40 p.s.i. This pressure is greatly reduced when the gas passes through service mains for delivery to the individual customer. The steel wall of the tube is.375" in thickness, and is bare of any corrosion retardant coating. The pipeline was not cathodically protected until November 11, 1963, when NFG installed magnesium anodes at various intervals on the pipeline. The anodes installed in 1963 were generally 250' apart. NFG installed two anodes in 1963 between Liberty and Poplar Streets, in the vicinity of the Marine Bank branch, at points 50' and 300' east of Liberty Street. According to pipe to soil potential surveys conducted before the anodes were installed, the potentials of the 20" pipeline in the area of the Marine Bank branch ranged from 600 mv. to 650 mv. NFG did not conduct a pipe to soil potential survey after the anodes were installed in 1963, and the next pipe to soil survey was not conducted until September 1970.
On January 13, 1970, the pipeline leaked at a point 247' east of the centerline of Liberty Street, and a quantity of gas escaped into the Marine Bank drive-in branch office at 38th and Liberty Streets, which was the same structure eventually destroyed by the explosion of December 13, 1973. NFG repaired the 1970 leak with a clamp and workmen excavated approximately 6-12' for visual inspection and conducted leak survey tests. NFG installed one or two more anodes on the pipeline at the point of the 1970 leak. A pipe to soil potential survey, done for NFG in September 1970, indicated that the pipe to soil potential of the 20" pipeline between Liberty and Poplar Streets was generally greater than 900 mv.
On December 18, 1973, the pipeline leaked again, this time at a point 230' east of the centerline of Liberty Street. The gas escaped through a telephone conduit into the Marine Bank drive-in branch. The gas exploded, demolished the drive-in branch, and injured Lou Ann Karle seriously. The cause of the leak was active galvanic corrosion. Immediately following the explosion, NFG workmen excavated the pipeline in the area of the 1973 leak and removed objects which may have been anodes. On December 19, 1973, a pipe to soil potential survey disclosed potentials of 650 mv. and 680 mv. in the area of the rubble of the drive-in branch. In addition, from 9:45 a.m. on December 18, 1973 -- the time of the explosion -- to 11 a.m. on December 19, 1973, NFG employees located gas escaping from the ground in explosive concentrations at several points around the drive-in branch.
From September 1970 to December 19, 1973, no pipe to soil potentials were conducted in the vicinity of Poplar and Liberty Streets on the 38th Street pipeline. NFG conducted other tests periodically to detect the presence of escaped gas.
On April 3, 1976, plaintiffs' expert witness conducted soil resistivity tests in the area of Liberty, Poplar, and 38th Streets, and found the average soil resistivity was about 6000 ohms-centimeter. The plaintiffs' expert witness, Fitzgerald, testified that these readings indicate that the soil in the drive-in branch area was moderately to very corrosive and that these readings reasonably indicate the soil condition at least since 1963.
Other facts established will be discussed in the context of the discussion of the legal principles to which they apply.
A. COMMON LAW NEGLIGENCE.
To establish liability under common law negligence, a plaintiff must prove that the defendant breached its duty of care to the plaintiff and that this breach of care was the proximate cause of the plaintiff's injuries. The extent of one's duty to another is variable and depends upon the probability and magnitude of harm and the cost of inconvenience of acting to prevent the harm from occurring, United States v. Carroll Towing Co., 159 F.2d 169, 173 [2d Cir. 1947].
In delimiting the duty of care of gas and electric companies, Pennsylvania courts have emphasized the extreme dangers that elements like gas and electricity present. "Where explosive compounds are in play, the measure of care arises with the degree of hazard involved," Hemrock v. Peoples Natural Gas Co., 423 Pa. 259, 223 A.2d 687, 692 . The power of uncontrolled gas and electricity
to destroy and disfigure is so great, that upon their purveyors the law imposes the "highest standard of care practicable," Densler v. Metropolitan Edison Electric Co., 235 Pa.Super. 585, 345 A.2d 758, 761 , quoting with approval Fitzgerald v. Edison Electric Illuminating Co., 200 Pa. 540, 543, 50 A. 161-2 . In the maintenance and repair of underground gas pipes, a gas company must take "every reasonable precaution suggested by experience and the known dangers of the subject." Moidel v. Peoples Natural Gas Co., 397 Pa. 212, 154 A.2d 399, 402 , quoting with approval Koelsch v. Philadelphia Co., 152 Pa. 355, 362, 25 A. 522, 524 . And when deciding if a gas company has met this very high standard of care, its conduct is not appraised by the knowledge of the intelligent layman, but rather by that of the expert in underground pipe corrosion, Hemrock v. Peoples Natural Gas Co., supra, 223 A.2d at 690. Finally, the existence of particular facts -- such as the age of the pipeline or the corrosiveness of the soil -- may elevate the gas company's standard of care to even higher levels, see Goodman & Theise, Inc. v. Scranton Spring-Brook Water Service Co., 352 Pa. 488, 493, 43 A.2d 111 .
A gas company's general duty of care with respect to underground pipes was summarized by the court in Hemrock v. Peoples Natural Gas Co., supra.
The responsibility of a gas company is to see to it that the highly inflammable commodity it is selling is contained within a casing, formidable enough to withstand the pressure or violence to which it could foreseeably be subjected.
223 A.2d at 689.