Company will use underground cameras to target problem pipes

Inspectors for the company that operates Boston's 22 miles of subterranean steam pipes will use miniature underground cameras and infrared aerial photography to identify areas that are leaking or could rupture, officials said yesterday.

Trigen-Boston Energy Corp. also plans to inspect its roughly 240 manholes and has hired an outside engineering firm to examine the company's operating and maintenance procedures.

The moves are part of a comprehensive assessment of the steam network requested by Mayor Thomas M. Menino after one pipe burst last month and another released a blast of steam. Representatives from Trigen met with city officials yesterday and offered an update of the review, which is scheduled to be completed by mid-December.

"We've asked them to use the latest state-of-the-art technology in completing the assessment," said James W. Hunt, the city's chief of environment and energy, as they look for "any breach of the integrity of the pipes, fissures, or cracks."

The cameras will be threaded into select pipes to inspect joints and other areas subject to weakening. In the next two weeks, inspectors with infrared cameras will fly over the city and create a thermal map to pinpoint sections of pipe that are too hot or too cold and need to be inspected. As a part of regular maintenance, Trigen employees will also visually inspect sections of pipe.

The process will be reviewed by Braintree-based Tri-Mont Engineering Co.

"We feel like [this process is] going to result in a better system and better service for our customers," said Nancy Sterling, a Trigen spokeswoman.

At yesterday's meeting, Trigen detailed the preliminary investigation of two recent steam pipe mishaps that sprayed several streets with insulation containing asbestos.

A burst pipe at Summer and Otis streets on Sept. 12 was probably caused by a phenomenon called a "water hammer," which occurs when hot steam hits cold water and changes the pressure in the pipes.

An Oct. 6 steam leak at New Chardon and Merrimac streets was probably caused by a bad expansion joint.

Both incidents remain under investigation.