Date: Fri 03-Oct-1997

Publication: Bee

Author: ANDYG

Quick Words:

Iroquois-pipeline-repair

Full Text:

Lightning Strike Forces Pipeline Repair

(with photo)

BY ANDREW GOROSKO

A preliminary inspection of a damaged Iroquois Gas Transmission System

pipeline section in Sandy Hook indicates it was struck by lightning, according

to an Iroquois spokeswoman.

Anita Flanagan of Iroquois said Tuesday a basic inspection found pockmarking

on a concrete jacket surrounding the natural gas pipeline, indicating a

lightning strike.

Monday at about 9:30 am, workmen vented gas from the pipeline near the

intersection of Church Hill Road and Walnut Tree Hill Road. The venting caused

an earsplitting noise similar to that of a large jet aircraft. A plume of

condensed water vapor shot directly up from the pipeline valve. The area was

redolent with an odorant mixed with natural gas to alert people to its

presence.

Gas is vented from the pipeline when major repairs are made to prevent

explosions.

After the gas was vented, workers about six miles away began to remove and

replace the damaged pipe section beneath Route 34 in Sandy Hook. The damaged

section was beneath Route 34 west of Great Quarter Road and east of Jordan

Hill Road.

In preparation for the pipeline repair, workmen had done substantial site

work. Sections of pipeline had been excavated on both sides of the road.

The workers used cutting torches to remove the damaged section. They then slid

a new length of pipe into place and welded it shut, covering it with a

concrete pipe jacket. The pipeline is 2 feet in diameter. Its surrounding

concrete jacket is 2« feet in diameter.

The pipeline section that had been vented of gas Monday morning was refilled

at about 10 pm that night after the repairs were made, Ms Flanagan said.

The damaged pipeline section will undergo metallurgical testing, she said.

To prevent damage from lighting strikes, the pipeline has a web of negatively

charged wiring affixed to it, Ms Flanagan said. The pipeline itself apparently

wasn't damaged in the lightning strike, she said.

Because Iroquois is dedicated to pipeline safety, the company took a very

conservative approach in the repair project, according to Ms Flanagan. The

375-mile-long pipeline stretches from Ontario, Canada, through New York State

and Connecticut, beneath Long Island Sound, and to Long Island.

Iroquois detected the imperfection in the pipeline beneath Route 34 by using a

tool known as a "smart pig." The tool was propelled through the pipeline by

gas pressure. The tool electronically scans the inner and outer surfaces of

the pipeline and finds pipe sections which aren't completely smooth. The "pig

run" through pipeline indicated there was an imperfection in the pipe section

beneath Route 34.

After such an imperfection is located, a visual inspection typically is made

to verify the data collected by the smart pig, according to Ms Flanagan. Such

an inspection typically is done by excavating the soil around the pipe. But

because the pipe section was located in a 30-inch-diameter concrete casing

beneath a state highway, a conventional inspection was impractical, according

to Iroquois.

Because the exact nature of the problem was unclear, Iroquois officials

considered the best approach to be completely removing the affected section

and replacing it with a new section rather than attempting maintenance work on

the flawed pipe in the field, Ms Flanagan said. Doing such field maintenance

takes several days rather than the one day needed for pipe replacement, she

added.

The area excavated on both sides of Route 34 to install the new pipeline

section will be restored, according to Ms Flanagan.