A LOOK AT THE BRITTLE-LIKE CRACKING OF THE GAS PVC TRANSMISSION OR DISTRIBUTION PIPES THAT CAUSED SIGNIFICANT LOSS OF LIFE AND PROPERTY DAMAGE
The exact cause of the natural gas explosion that killed eight people, injured at least 68, and displaced 100 others when it leveled two buildings in East Harlem in March hasn’t been determined, but it is known the block was serviced by a leaking 127-year-old cast iron main.
A considerable amount of degradation and some corrosion, probably from repair parts for the 1880s-era system, was visible as crews installed a new section of polyethylene pipe under the street in New York City.
In the first half of the 20 century, cast and wrought iron pipe were used, which resist corrosion but can be damaged by ground settlement, freezing/thawing, and excavation. These pipelines were built to transport manufactured gas, but when they were switched to drier natural gas, pipes dried out and became brittle.
Cast iron pipe is not the only source of leakage: construction techniques of welding and joining have changed and improved over the century, but many older systems suffer from leaks due to outdated methods. However, cast iron pipe tops the list of problem pipelines.
As a result of that special investigation, the National Transportation Safety Board issued recommendations to the Research and Special Programs Administration, the Gas Research Institute, the Plastics Pipe Institute, the Gas Piping Technology Committee, the American Society for Testing and Materials, the American Gas Association, MidAmerican Energy Corporation, Continental Industries, Inc., Dresser Industries, Inc., Inner-Tite Corporation, and Mueller Company.
There are 2 million plus miles of distribution pipeline in the country. The Pipeline and Hazardous Materials Safety Administration (PHMSA) estimates that less than 3% are cast or wrought iron. Since 2004, the number of cast iron main lines decreased by 16% and service lines by 66%, replaced by plastic or steel pipelines. In 2012, however, there were still 34,000 miles of cast iron main lines and 15,000 miles of service lines.
How dangerous are deteriorating pipes? In addition to causing deaths and injuries, leaks and subsequent explosions damage property, disrupt business and power to consumers. Leaks can damage the environment and released methane is a greenhouse gas.
Reporting of actual incidents has become mandatory only recently, and accuracy is problematic because, as PHMSA states, reporting criteria “has changed both significantly and multiple times over the years.” Giving this caveat, PHMSA recorded 2604 incidents between 1994 and 2013, with 289 fatalities and 1,080 injuries.
PHMSA data in 2009 indicates that there was one leak per every 8 miles of main line and one leak per every 2 miles of service lines. Not all these leaks are attributable to faulty pipe, but PHMSA reports that 31% of incidents between 2008 and 2010 are attributable to material and/or weld failures. Cast iron pipe poses the most significant problem:
- 11% of all main line incidents involve cast iron, but it comprises only 2.6% of the lines
- 37% of iron main line incidents caused a fatality or injury, other materials caused a fatality in 21% of incidents
- 67% of iron service line incidents caused a fatality or injury, other materials caused a fatality in 32% of incidents
What has been done about this problem in the past? PHMSA reports that incidents involving death or injury have been reduced by half over the last 20 years, because of pipelines “gradually improving safety performance.” This improvement comes from better material, better construction techniques and better leak detection technology.
Why do we still have a problem with aging, deteriorating pipe? Although the technology exists to improve the entire distribution system, many challenges exist. First, operators have to know where to replace pipe, cast iron or not. PHMSA only recently began to “become a data-driven organization” for collecting data on our pipeline infrastructure and industry performance, and only recently have operators been required to report the type of material in pipelines and their history of incidents.
Second, deteriorating pipe may be difficult to replace. Unfortunately, much of the old cast iron pipe is buried in densely populated urban areas. Access is very problematic, as well as gas service disruption, traffic disruption and getting local authorities to issue permits.
Third, inspections require highly trained technical personnel. Even now, expertise and sheer manpower may be lacking, according to the NTSB and engineering experts. PHMSA does have a “Training and Qualifications” team that communicates new regulation to operators and conducts seminars, but more technical assistance is needed and companies must satisfy the operator qualification rules.
Because of the difficulties involved, the cost to accomplish replacement is in the billions of dollars. This is money that most companies may not have, and probably will not have because of the current approach to rate-making at both the Federal and State level.
As reported by PHMSA in 2011, many States have mandated pipeline replacement programs for some types of older pipes. Some states have incentivized operators to replace cast iron pipe by providing operators with rate relief to accelerate replacement. However, some of these replacement programs in the larger states are not scheduled for completion for many decades.
In fact, The PHMSA reports that the ten states that have 80% of the cast iron main lines in the country, have extremely long-term, if any, replacement goals:
These programs must be accelerated if more deaths, injuries and property damage are to be avoided. PE is the plastic replacement material of choice for modernizing the natural gas distribution system — so much so some are concerned about resin and pipe shortages. However, Performance Pipe expects the plastics industry to keep up with demand. Our concern though is with quality of the pipe, considering the significant demand and the rush to meet it.
Demand for next-generation plastics, like PE pipe, started rising in 2009 and really picked up in 2011. That’s when the federal government required natural gas utility operators to have a distribution integrity management plan (DIMP) in place to address the highest risk segments of their systems. There’s still roughly 30,000 miles of cast iron in the ground in distribution, but 10 years ago there were 40,000 miles so it is being replaced over time.
Plastic pipe has several advantages over steel pipe; however, plastic is more susceptible to damage from digging, static electricity and it requires the use of tracer wire to locate during excavations. Bar codes are gaining traction.
New Jersey Gas Pipeline Problem
New Jersey’s aging gas mains last year had twice the number of hazardous leaks than the nation’s gas mains on the whole. Faced with alarms raised by federal authorities over the safety of old pipes, the four gas utilities operating in New Jersey are working to replace older stocks of bare-metal or coated but unprotected mains with plastic or steel pipes that have protective coating. North Jersey-based Elizabethtown Gas Co. has the state’s highest leak rate: 97.3 hazardous leaks per 1,000 miles of mains.
New Jersey has 5,000 miles of the type of gas mains that raise the most concern for safety: cast iron. About 17 percent of New Jersey’s 34,000 miles of gas mains were made up of cast iron or bare steel at the end of 2013 — or 6,437 miles. The national average is 7 percent.
Between 2007 and 2013 in New Jersey, cast-iron mains have been reduced by 717 miles and bare-steel mains by 574 miles, according to the BPU.
That dropped the miles of bare-metal mains over that six-year period by about 3.3 percent a year. If the pace continues, the old mains would be replaced in 30 years.
And in the six-year period, 101,376 bare-steel service lines have been replaced with new pipe. At the end of 2013, there were about 270,000 bare-steel service lines — those that run from gas mains to customers’ buildings. If that rate of replacement continues, it would take about 16 years to switch them all. There are no cast-iron service lines.