Deadly South Auckland blast: How it may have happened

One contractor was killed and four people were injured when a tank exploded at Salters Cartage. Photo / Nick Reed

Flame cutting and welding could cause an industrial fire or explosions if proper safety procedures were not in place, an industry expert says.

Jamey Lee Bowring, 24, of Huntly, died in an explosion at an industrial site in South Auckland yesterday.

The explosion rocked buildings kilometres from the scene and sent eyewitnesses diving for cover. It was so violent that one nearby worker thought an aircraft had come down.

Salters Cartage managing director Ron Salter said two contractors had been on site, measuring some walkways. One decided to do some welding, without permission, causing a tank to explode.

Emergency services rushed to the industrial site. Photo / Greg Bowker

Senior Welding Engineer for the New Zealand Welding Centre Alan McClintock said while he was not able to comment specifically on yesterday's accident, in general, flame cutting and welding could be a cause of industrial fires and explosions if suitable safety procedures were not implemented.

Mr McClintock said in New Zealand all welding must be carried out in accordance with the applicable standards and statutory regulations.

"In cutting and welding the elimination of heat is not possible, therefore most strategies are based on elimination of fuel and oxygen while minimising the spread of heat.

"Therefore close monitoring and supervision of welding activities are required to prevent incidents."

According to codes all hot work must be supervised by a person who is responsible for the safe execution of all operations.

Before hot work was carried out in any location, that person had to ensure the hazards of the location were identified and appropriate safety measures were put in place to minimise risks.

Mr McClintock said that also included testing to ensure that no flammable gas or vapour was present.

A large fragment of what is believed to be a fuel tank has been propelled about 100 through the air and landed on the roof of a car. Photo / Greg Bowker

No hot work was permitted without compliance with all of the requirements of the standard, he said.

"If implemented properly, welding safety procedures will provide a sufficient safety margin to prevent welding-related accidents form occurring," Mr McClintock said.

"The key to achieving this is adequate staff training in particularly at the level of the person supervising the welding."