Other recommen-dations include a call for the gas company to improve maintenance records and procedures.

The explosion happened at 21 Linfield Street in the Happyhillock area on October 22, 2000.

William (67) and Mary (58) Bailey died in hospital from injuries sustained in the explosion.

The house next door to theirs was destroyed and their neighbour — a widow in her 60s — was badly injured.

The investigation has concluded the blast was caused by gas leaking from a fracture in a four-inch cast iron main.

The probe was overseen by a special board formed by the HSE because of public concern over previous gas incidents.

It recommended all cast iron mains in the Happyhillock South 2nd Development should be replaced by polyethylene mains. Transco carried out this replacement shortly after the incident.

The board has further recommended any cast iron mains in similar situations in Dundee — those over what was described as “improperly constructed drainage tracks and in close proximity to housing” — should also be “identified, examined and replaced as soon as possible.”

It also asks Transco to take account of “local factors” in its replacement policy; that the company should improve itsmaintenance records and procedures; and that Transco investigate the reasons why the public sometimes do not report gas escapes and to use this information to help improve public awareness and reduce the risks of escapes going unreported.

The HSE’s specialised industries division head, Dan Mitchell, said today that while accidents such as the Linfield Street blast have reduced over the years, each they were always a personal tragedy for those involved.

In June, 2001, the HSE sent a report to the Procurator Fiscal in Dundee in connection with the Linfield Street explosion.

More than two years later it was said no charges were to be laid in respect of the incident. It was also decided there would be no fatal accident inquiry held.

The HSE special board noted a legislative change had been enacted which would require pipeline operators such as Transco to comply with a mains replacement programme agreed by the executive.

In a statement this afternoon, Transco said it noted the decision not to take action against the company following the Linfield Street accident.

“Transco has co-operated fully with all parties involved in the investigation and believes today’s decision is the correct one,” the statement said.

“The company is however acutely aware of the distress felt by the family and friends of Mr and Mrs Bailey, and again wishes to express its deep regret over this tragedy.”

The company con-firmed that immediately following the incident, it replaced all metal gas mains in the vicinity of Linfield Street and the Happyhillock estate.

“In the last few years, Transco has accelerated its programme of replacing metal gas mains with more flexible polyethylene pipe.”

The HSE said today poly-ethylene is now used for all new and replacement low and medium pressure mains.