The Australian pipeline industry can be proud that there has never been a death or serious injury caused by failure of an operating pipeline. But that exemplary record can hang by a thread …
The APIA/POG pipeline incident database has received reports of two events that I thought were stomach-churning scary:
- A D10 dozer ripping to 1200 mm depth passed over a pipeline twice and stopped just short of another pipeline in the same area; the pipeline crossed was at about 1350 mm depth (phew!)
- A 1.2 m diameter pole auger (for a large power pole) was all set up to drill on a transmission pipeline easement; it was stopped by a patroller for a separate gas distribution business who passed by on other work and just happened to notice the auger (phew!)
If the crews operating the ripper and auger were the type of people who buy lottery tickets on lucky days they should have gone and bought dozens. (But I think that lotteries are a tax on people who can’t do maths.)
Both of these threats had been considered in a generic way in the safety management studies for the pipelines and both had been judged to be adequately controlled by the procedural measures in place. In a sense the controls worked because there was no damage or failure but in both cases the multiple levels of protection were reduced to one (depth of cover in the case of the ripper) and nil plus luck (in the case of the auger, against which there is essentially no effective physical protection). Paring the multiple barriers down to one or just luck is not a comfortable position.
Some general comments prompted by these incidents:
- The industry must never be complacent about the things that might be done to pipelines (complacency is too easy when it comes to low-probability but high-consequence events).
- Procedural protection measures can and do fail despite the fact that there may be several of them (pipeline awareness programs, dial-before-you-dig, warning signs, etc).
- The “controls fail” scenario in an SMS workshop can come uncomfortably true.