with TGF3, a coal tar base coating. According to Calnev’s cathodic protection-records, the pipe had a minimum negative (cathedic) voltage of 0.85 volts (generally it had a considerably more negative voltage) as measured between the pipe and the soil. A cathodic protection rectifier was located at the Colton Pump Station, and Calnev’s records indicate that there had never been a corrosion leak found on this 14-inch pipeline system. Calnev’s manager of operations testified that if the coating damage existed prior to the derailment Calnev would not have been able to see any change in the cathodic protectton in this case because, "There is a casing that runs under Highland Avenue. At this particular location the casing and the pipe are operating at the same potential. That large casing would probably mask any damage to the coating that might be evident in that location. I don’t think you would have seen a change to the cathodic level there."
The first 107 miles of the pipeline were hydrostatically tested between June 20, 1970, and July 3, 1970; the section through the rupture site (MP 0.0 through MP 25.2) was tested on June 29 and 30, 1970. The pressure test on this section was begun at 8:15 a.m on June 29, 1970, at 2,085 psig and completed at 12:30 p.m. on June 30, 1270, at 2,083 psig. The minimum pressure during the test was 2,075 psig, and the minimum 4-hour internal sustained pressure.was 2,077 psig.
Check Valves.—At the time the pipeline was constructed, Calnev installed check valves in its pipeline to prevent backflow of product from one section of the pipeline to another. These valves also serve to minimize the amount of product that can be released from the pipeline should the pipeline rupture. Generally, Calnev installed top-hinged check valves, and at some locations there are connections installed to bypass the check valves. However, on the 14-inch portion of the pipeline, Calnev installed seven Wheatley "All-Clear Check Valves." These check valves are side-hinged check valves which purportedly provided advantages over the top-hinged check valves by producing less pressure drop and offering less resistance to the passage of spheres and scrapers. Side-hinged check valves were installed at MP 0.0, 6.9, 14.9, 19.2 and 25.7. Calnev’s manager of operations testified that he was not aware that Calnev had ever inspected any of the check valves installed in the pipeline between the Colton pump station and Cajon Pass to determine if the valves operated properly. He further testified that it was his understanding that check valves are not routinely inspected in the industry and that he was unaware of any Federal regulation or industry standard that required such inspection. He stated that following the rupture Calnev made plans to inspect the check valves in this area. In a letter to the Safety Board dated May 21, 1990, Calnev stated, "Calnev has installed four new check valves; three to replace existing check valves and one additional check valve at MP 10.0. Our intention is to replace one more check valve and install a supplemental block valve near another in the next 60 to 90 days."The OPS representative who testified at the Safety Board’s public hearing stated that the proper operation of check valves can be important to the safe operation of pipelines; he also advised that the OPS historically has considered that the regulations do not apply to the maintenance of check valves. The OPS has not issued an interpretation to this effect and it has