The Discworld series of novels by Terry Pratchett present an entertaining combination of comedy and sardonic commentary in a bizarre fantasy world. (Pratchett also shows a very good grasp of scientific and technical matters.) In Thief of Time a senior monk says to a novice something like “That’s why we have rules – so you think before you break them”.
Quotes like this hint at an important lesson about design and standards.
It’s impossible for a complex standard on a complex subject (such as AS 2885) to cover every conceivable situation. Certainly a standard must contain some rules, but the philosophy of AS 2885 is that it is a standard for design (and operation) by thinking, not by blind application of rules. If robotic applications of rules was possible someone could make pipeline engineers redundant by codifying it all into a software package.
So pipeline engineers are required to think, within the constraints of the rules set down by the standard, but those rules are not necessarily absolute. Let me point you to Clause 1.6.2 of AS 2885.0:
1.6.2 Departures from the Standard
It is not intended to prohibit the use of any materials, designs, methods of assembly, procedures or practices that do not comply with the specific requirements of the Standard, or are not mentioned in it, but do give equivalent or better results to those specified. Such departures shall be approved.
Relying on this clause is not something that you do lightly. On the other hand it shouldn’t be overlooked when you are confronted by a situation where black-letter application of the rules leads to an outcome that is seriously sub-optimal.
For example: Not so long ago I was involved in a project where under very unusual conditions there was a slight possibility that pressures could temporarily exceed MAOP. Clause 7.2.1 of AS 2885.1 allows up to 110% MAOP under transient conditions, which for gases it defines as having a duration of “seconds or minutes”. In this case the duration was possibly many hours, although the probability of it occurring at all was very small. This seemed to be a situation where the AS 2885 safety management study approach would be helpful in analysing the failure that would lead to the temporary overpressure – assess the likelihood of occurrence (very small), assess the consequences (nil, for all practical purposes), determine the risk rank, and then decide if the risk is tolerable.
Unfortunately the issue attracted the attention of other disciplines and management who were not in touch with the risk-based approach and who could not see past the apparent breach of Clause 7.2.1 and its definition of “transient”. I don’t think it’s going to far to say that there was an obsession with black-letter compliance with the code, regardless of common sense. Ultimately common sense did prevail, but only after the expenditure of what must have been hundreds of hours of engineering time including an all-day risk assessment workshop involving lots of highly paid people.
I’m not suggesting for a moment that this “breach” of the AS 2885 rules should have been glossed over. It deserved serious assessment of the likelihood and a good understanding of the consequences, and it all needed to be properly documented and approved. The point I am making is that AS 2885 explicitly allows its own rules to be breached when the the proper process is followed. Obsession with strict compliance is misguided.
Another quote I like is from Douglas Bader (the double amputee WWII pilot known as “Tin Legs Bader”): “Rules are for the obedience of fools and the guidance of wise men.” But you need to be very careful about applying this too liberally. Bader lost his legs by breaking the rules, apparently lacking sufficient wisdom at that stage of his career.
So we have rules, to be followed strictly wherever possible, and for guidance the rest of the time provided you think before you break them.