Cast Iron Pipeline R&D Projects
Key Message: Cast iron gas mains and services (more limited) have been installed since the 1830’s in the U.S. They are still in service in many cities including Boston, New York, Philadelphia, Baltimore, D.C, Detroit, Chicago, and San Francisco. Replacement of pipe in urban areas can be technically difficult, extremely expensive, and pose secondary risks.
It comprises predominantly a gray cast iron tube and was frequently used uncoated, although later developments did result in various coatings and linings to reduce corrosion and improve hydraulics. Cast iron pipe was gradually superseded by ductile iron pipe, which is a direct development, with most existing manufacturing plants transitioning to the new material during the 1970s and 1980s. There is currently almost no new manufacture of cast iron pipe.
Background: Recently there have been two significant incidents possibly resulting from the failure of cast iron mains in natural gas distribution service. One incident occurred on January 18, 2011 in Philadelphia, Pennsylvania and the other occurred on February 9, 2011 in Allentown, Pennsylvania.
Natural gas distribution mains and service lines are composed of several different pipe materials as systems were constructed during the 19th and 20th Century. As of December 31, 2009 plastic and steel pipe made up approximately 97% of the mileage of natural gas distribution pipelines. The remaining 3% is primarily iron pipe, either cast iron or ductile iron. Ductile iron pipe was first manufactured in 1955 and its use was very limited due to the advantages of steel pipe that was available during this time. Cast iron pipelines were first constructed in the 1830s but were widely used in the early decades (pre World War II) of the 20th Century.
Recognizing its age and certain potential risks with cast iron pipe, several states have initiated programs to incentivize operators to replace cast iron pipe in their systems. Some state agencies with pipeline ratemaking authority have provided operators with rate relief to accelerate the rate of replacement. PHMSA’s recently published Distribution Integrity Management Program rule could cause operators to identify concerns resulting in additional cast iron pipeline being replaced on a more expedited schedule.
Major Cast Iron Main Data (obtained from PHMSA database and NAPSR survey)
- At the end of 2004, 41,501 miles of cast iron main were remaining in natural gas distribution service compared to 35,624 miles of cast iron main as of the end of 2009. The mileage of cast iron mains was reduced by 5877 miles (14.2%) over the five year period.
- At the end of 2009 cast iron distribution pipelines were operated in thirty states.
- Fifty percent of the mileage resides in four states: New Jersey, New York, Massachusetts and Pennsylvania.
- Eighty percent of the mileage resides in ten states: New Jersey, New York, Massachusetts and Pennsylvania, Michigan, Illinois, Alabama, Connecticut, Maryland and Missouri.
- The National Association of Pipeline Safety Representatives (NAPSR) has reported (as of 46 responses on 2/13/2011) that (twenty two of the thirty states with cast iron mains) have cast iron main replacement programs. Of the ten states that contain eighty percent of the cast iron main mileage (as described above), Maryland is the only states that does not have a cast iron replacement program. Seven of the eight states (Massachusetts has no projection for completing cast-iron replacement) with replacement programs have reported that their replacement programs should be completed by projected dates as follows: New Jersey – 2035; New York – 2090; Pennsylvania – 2111; Michigan – 2040; Illinois – 2031; Alabama – 2040; Connecticut – 2080; Missouri – 2059.
PHMS Cast Iron Pipe Regulations:
- Gas – 49 CFR Part 192 – 192.275, 192.369, 192.373, 192.487, 192.489, 192.557, 192,753, and 192.755
- Liquid – 49 CFR Part 195 - not allowed
Industry codes and standards:
- ASME/ANSI B16.1 - 1998 - Cast Iron Pipe Flanges and Flanged Fittings -This Standard for Classes 150, 300, 600, 900, 1500, and 2500 Cast Iron Pipe Flanges and Flanged Fittings covers
State Specific Requirements
- Cast Iron Replacement: Some State pipeline safety authorities have mandated operators replace all or parts of their cast iron systems. Atlanta (15 year replacement of all cast iron and bare steel, to be completed in 2013) and the District of Columbia (10 year replacement of the 8-inch and 12-inch cast iron pipes, completed in 2004) are two examples. When State authorities mandate the pipe replacement program, operators are generally assured that they will recover their costs through their rate base. If the program is voluntary, the operator does not know if the cost is recoverable until they file rate case.
- Kansas expanded on 192.755 requirements to include mandatory pipe replacement [K.A.R. 82-11-4 (ee)]
Program Accomplishments: In FY2008, the Pipeline Safety R&D Program completed a research project related to cast iron pipe. A summary follows:
Ultra-low Frequency Pipe and Joint imaging System: Main Objective: The project developed tested and independently assess the commercial viability of a pre-commercial pipe and joint imaging system. An added feature demonstrated is the accuracy location of both horizontal and vertical positions of the pipe and distinguish from other underground clutter in dense environments that are typical of suburban or urban areas. Results: The imaging tool was further developed, tested and successfully demonstrated to prospective commercial partners that it can locate pipes and cast iron joints in all types of soils, including some of the most difficult soils for imaging; clays soils. The imaging tool also successfully demonstrated to the gas utilities the ability to accurately locate cast iron pipes, bell and spigot joints that with existing tools cannot be located or are missed resulting in unnecessary excavations. “Dry holes” and added cost while disruption to the public. For additional information go here.
Future Research plans: Since FY2004 PHMSA’s Pipeline Safety Research Program has sponsored four (4) Government/Industry Forums. The most recent Government/Industry Pipeline R&D Forum was held in FY2009. The 2 day event included representatives from Federal, State and international government agencies, public representatives, research funding organizations, standards organizations, and pipeline operators from the U.S. and overseas.
The objectives of the R&D forums are to facilitate government and industry pipeline stakeholders to develop a consensus on the technical gaps & challenges for future R&D. It addressed both short and long term research objectives for liquid and gas and transmission and distribution pipelines, covering onshore, offshore and Arctic environments. In addition, details of the ultimate research goals, technology demonstrations, and transfer and commercialization were discussed.
The next government/industry R&D forum scheduled for July 18-19, 2012 in Arlington, VA will open up discussions on the technology gaps, standards/regulations updates and general knowledge relating to cast iron pipe usage. The forum will create a roadmap for the necessary future research that will bring solutions to these growing concerns. Please find further details about forum form the event meeting page at http://primis.phmsa.dot.gov/meetings/MtgHome.mtg?mtg=77.