Expert says gas could have caused explosion — but Egoli Gas says no

The explosion which rocked Lilian Ngoyi (formerly Bree) Street in the Johannesburg CBD on Wednesday afternoon could have been caused by an impact to one of the gas lines under the street, an expert has speculated.

Twenty-four hours after the explosion, there has been no official word on the possible cause. 

Dr Phathutshedzo Rodney Khangale, senior lecturer in the department of chemical engineering technology at the University of Johannesburg, said on Thursday that natural gas was being transported by companies to clients using pipelines running beneath the streets.

He said natural gas is made of methane and is flammable.

“If you are transporting gas using a pipeline, it will be at a certain pressure — higher than the surrounding pressure,” Khangale said.

He said some gases were transported under pressure.

“If you have a gas like methane, which can easily ignite, even static electricity can spark an ignition. If the temperature changes, the gas expands as particles move quicker with heat.”

Khangale likened this to an inflated balloon — if it was left in the sun it could burst because of the change in temperature.

Khangale said if a gas pipeline was “pinched” and started to leak, this could affect the outside temperature and cause a spark.

“The fact that the explosion caused extensive damage means that the pressure in those gas pipes was very high.”

However, Egoli Gas has said in a statement it believes it is unlikely that the explosion was caused by a gas pipeline leak.

“Our network has experienced no pressure loss, which indicates the gas pipelines are intact. Our customers in the area continue to receive gas uninterrupted,” the utility said.

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