IMP Guidance Docs - Pipeline Risk

Guide to the Guides

Here is a quick evaluation of some of the key documents offering guidance on pipeline system risk assessment and risk management. Not all of these are guidance docs, some are industry stds but we’re listing them as ‘PHMSA’ because they are, per PHMSA, either mandatory or suggested elements of compliance with US regulatory pipeline IMP

We’ve also added a few PHMSA-sponsored research studies, commissioned to help in the understanding of IMP related issues

Basis of Ratings:

Useful?
Complete?
Correct?

‘Summary’ in the table below is a soundbite of our criticism or advice on whether its worth your time to review or read. The former implies gaining some familiarity while the latter implies really trying to use the content in your own operation.

It may be tempting to believe that government-issued or endorsed guidelines are the result of the best and brightest minds coming to complete agreement using the latest science and technology. The reality is that, due to lack of technical clarity, expert consensus, or maybe due to liability concerns or need for compromises, we don’t always get the best advice, especially in the early versions.

Title	Focus	Summary	url	Rating	More
Risk Modeling Group	RA methodologies	good summary of current practice; decent conclusions; errors regarding ‘threat interaction’	URL	B	don’t compromise your risk model; PRA is a subset of QRA; sections on CoF and Appendix on conversions from scoring systems are good; NO threat interaction system is ever needed in a properly designed risk assessment
Re assessment interval	largest remaining defect and degradation rates	must read and implement	URL	A	this is a short doc and the title is misleading. but worth a read. it highlights the essential aspect of estimating a TTF as part of an IMP. TTF is estimated via two inputs: largest remaining defect and degradation rate. basic stuff, but surprising how many are not making this a part of their IMP, regulatory or not.
Guided Wave	uses and limitations	know that it exists	URL URL2	C	Sometimes proposed as an alternative to ILI or pressure test, this technique has pros and cons; not fully quantified in guidance
Inspection Protocols	Auditors’ expectations	must review		A	These are sometimes used directly in a regulatory inspection.
PHMSA FAQ’s	must review	should review		A	Always a good source for clarifications
Baker TTO5	impact radius estimates and assumptions	know that it exists; note all assumptions		C	see PIR
Baker TTO4	impact radius estimates and assumptions	know that it exists; note all assumptions		C	see PIR
B31.8S	full IMP gas trans	become familiar; note significant errors in how risks and threats are addressed		C	Updating guidance docs
API 1160	full IMP haz liq	repeated errors in B31.8s		C	same issues as with ASME B31.8s
NPRM Fed Register		must read		A	Usually very well written and full of useful background information on proposed or new regs.
SHRIMP	DIMP RA	disregard		D	Overly simplistic, does not lead to true understanding of risk.
195 IMP Appendix	RA for IMP	very outdated advice		D	Overly simplistic, does not lead to true understanding of risk.
LDS study	Leak detection capability study	become familiar		C	Good background discussions; insufficient guidance on capability analysis
EFRD study	Emergency Flow Restricting Device Study	become familiar; has a fatal flaw		C	Good discussions but erroneous conclusions