Hugh Kerr, a retired Waterloo professor who specialized in welding processes and metallurgy and has trained some of Canada's top pipeline engineers, agrees.

"Automatic ultrasonic testing is much better at picking up defects from different orientations and lots of people are saying that."

Yet it costs more and can slow down the pace of construction. "Industry would rather get the pipe in the ground and deal with the problems afterwards," explains Vokes.

When industry opts not to use best practices such as AUT, the reasons can be accounting or scheduling decisions.

Kinder Morgan's Rocky Express pipeline again makes a perfect example. Although Kinder Morgan did employ AUT for the main line of the pipe, all repairs were inspected with a less reliable method that didn't catch hundreds of cracks.

The following eyewitness industry email obtained by the Tyee documents the scale of the negligence (hundreds of digs to repair the line) as well as the inadequacy of the company's welding inspection system.

"The repair process was set in place that a 24 hour delayed inspection was not necessary due to the metallurgical properties of the welding rod that was supposed to be used. Repair welders on the pipeline thought it was much easier to weld using Cellulosic welding rods and made the executive decision themselves to go that route not realizing the ramifications of their actions. Obviously the client was not aware of the change in the procedure and therefore did not mandate a post 24 hr inspection requirement and when it came time to Hydro-Test there were multiple failures all propagating from the repair areas due to post 24 hr cracking caused by the use of Cellulosic welding rods without proper inspections. All repairs done using the Cellulosic rod had to be excavated and re-repaired or cut-out causing major delays and massive financial repercussions also giving a black eye to the industry."

The National Energy Board issued a safety order against the company and its TransMountain pipeline in 2011, saying its inspection system for cracks was inadequate. Moreover, its chosen system was "not presently an accepted practice by industry."

Northern Gateway inspection issues

Similar issues dog the proposed Northern Gateway project. Enbridge, for instance, has told the National Energy Board that it may or may not use radiography and a process technically known as sectoral scan ultrasonics to check for bad welds.

The technology resembles the ultrasound machine used to scan fetuses in the womb: "Just as determining a baby's sex can be as problematic, finding a crack with a sectoral scan is more difficult than AUT -- the resolution for ultra sonic isn't that good," explains Vokes.

Although gamma radiography is a traditional technique in pipeline construction, it is also known as "the welder's friend" because of its inability to pinpoint defects. "You can see them but you don't know what they are." Companies proposing technically difficult projects in challenging northern geographies should not be allowed to use radiography as their only examination tool, says Vokes. Nor does he think regulators should allow only radiography to test welds.

A second problem with non-destructive examination concerns conflict of interest. An independent third party should do it, and not the contractor hired by the company to weld the pipe.

Yet in many cases pipeline companies don't hire an independent contractor to inspect the welding procedures or weld quality during the construction process. Alberta's provincial regulation, for example, does not prohibit contractors from hiring all inspection in house -- an inherent conflict of interest.

However federal regulations require all non-destructive examinations under Construction of Pipelines CSA Z662 to be performed "by an independent contractor retained by the company." (Yet the same federal regulation allows the companies to set the techniques and qualifications of inspection, adds Vokes.)

There are other problems with the state of non-destructive examination. The skill requirements under some codes for inspectors allows for inexperienced people to conduct and interpret welding inspections. After a short course, just about anyone can write a qualifying test in pencil, explains Vokes and he doesn't think that sort of training is rigorous enough. "It's another inherent conflict of interest in the whole process."

The failure of in line inspections

Industry lobbyists claim that safety programs routinely protect the public and the environment from pipeline failures with scheduled in-line inspections that might include x-rays, machines called pigs, special monitors or aerial surveys.

Yet companies fail to detect problems on their pipelines all the time, says Vokes.

A recent review of U.S. pipeline data by InsideClimateNews found that 19 out of 20 pipeline leaks aren't detected by remote sensing systems. Landowners and employees at the scene of ruptures report the majority of all incidents.

The U.S. National Transportation Safety Board also makes a similar point in its sweeping critique of Enbridge safety practices on Line 6B prior to the Michigan bitumen spill.

Reports the NTSB: "Despite their sophistication, the detection capabilities of in-line inspection tools have limitations. Each tool technology has a stated minimum defect size that can be detected and the tool can be subjected to interference from nearby anomalies or geometry."

As a consequence pipelines routinely fail and crack without warning.

In 2007 Enbridge's Line 3, for example, ruptured, spilling oil near Glenavon, Saskatchewan.

Both the company and the NEB had identified the line as susceptible to cracking because of 10 major incidents from seam failure to metal fatigue on the line since 1989.

Nevertheless a 2002 field inspection and a 2006 ultrasonic test failed to detect the anomaly responsible for the 2007 rupture because it "was not identified as requiring immediate repair since its depth was in the 12.5 to 25 per cent range" of wall thickness. (Cracks grow to become like half ellipses, before fracture occurs.)

Investigators concluded, "It is apparent that a degree of uncertainty can exist during the non‑destructive examination of the pipe in the field" while it is in service.

In 2009 Enbridge's Line 2 crude oil pipeline from Edmonton to Cromer, Manitoba, also cracked and spilled oil. A landowner found the leak thanks to a strong petroleum odor downstream of the Odessa pump station.

Despite a battery of inspections in 1998, 2004, and 2008 for cracks and metal loss and other problems, Enbridge missed the dent and gouge that resulted in the crack.

In fact, the dent that eventually turned into a crack had escaped detection since the pipe was laid in 1953 until 2004. Noted a 2009 incident report by the Transportation Safety Board of Canada: "The dent was detected during the 2004 metal loss in-line inspection. However, the metal loss associated with the gouge was below the detection limit of the ILI tool and the location was not flagged as a dent with secondary damage. No follow-up was performed after the 2004 inspection as the size of the dent was within company specifications. In 2008, the dent was again detected during the geometrical discontinuity in-line inspection. Again, as it did not meet Enbridge's damage reporting criteria, it was not flagged for further follow-up."

In 2011 an Enbridge pipeline carrying oil from Norman Wells to Alberta cracked and leaked more than 1,000 barrels of oil. The leak was due to a small crack on a girth weld on the pipeline and is currently under investigation. The Board ordered the company to conduct aerial surveys of the pipeline as well as reduce the pressure at which oil is pumped through the line.

NEB 'knows' inspections miss defects: Vokes

Vokes says the Norman Wells leak not only represents another failure of in-line inspection but also highlights the difficulty of keeping pipe safe in challenging terrain and climate.

"Does the National Energy Board know that in line inspection misses defects? It knows," says Vokes. "In line inspection won't take care of all latent defects found near girth welds."

In other words the best defense against leaks, cracks and ruptures lies in proper welding procedures. Next comes an immediate and rigorous inspection process enforced by transparent regulators, says Vokes.

Given that the pipeline industry proposes to double the nation's pipeline capacity over the next decade, the issues raised by Vokes deserve careful regulatory and political scrutiny.

"The engineers are doing the best they can. But the companies push them to get the pipe down by so many kilometres a day," adds Kerr, the retired welding expert.

"We are all shareholders in this process and want larger returns and that happens by cutting costs in the industry. It seems to me that this process can be a race to the bottom unless we make sure that the pipeline companies fabricate and properly maintain well designed pipelines."

Next: Evan Vokes on Gateway: "A pipeline without a seatbelt."