API RP 1170 and 1171 Second Editions: A Practical Procedure Gap-Analysis Workflow

PHMSA incorporated the second editions of API Recommended Practice 1170 and API Recommended Practice 1171 into 49 CFR Part 192 effective January 1, 2026. For underground natural gas storage operators, the resulting task is easy to describe but difficult to execute:

Determine what changed, identify which facilities and activities are affected, and verify that current procedures and supporting records address the applicable requirements.

That is not a simple document-comparison exercise. A revised provision may affect several procedures, roles, forms, training materials or record systems. Conversely, one operating procedure may address several requirements. The relevant evidence may be distributed among controlled manuals, facility-specific instructions, integrity-management documents, inspection records, engineering analyses, database records and scanned legacy files.

A defensible gap analysis therefore needs to show more than whether similar language appears in two documents. It must show how each applicable requirement is implemented and what evidence supports that conclusion.

What PHMSA changed

The 2025 direct final rule replaced the previously incorporated 2015 editions with:

• API RP 1170, second edition, November 2022 - Design and Operation of Solution-mined Salt Caverns Used for Natural Gas Storage.
• API RP 1171, second edition, November 2022, including Errata 1 from September 2023 - Functional Integrity of Natural Gas Storage in Depleted Hydrocarbon Reservoirs and Aquifer Reservoirs.

At a high level, RP 1170 applies to solution-mined salt cavern storage and addresses the cavern well system and related integrity, operating, monitoring, maintenance, safety and abandonment practices. RP 1171 applies to storage in depleted hydrocarbon and aquifer reservoirs and addresses storage wells, reservoirs and fluids throughout design, construction, operation, monitoring, maintenance and documentation.

The regulatory context matters. Section 192.12 of 49 CFR requires UGS operators to prepare and follow facility procedures for operations, maintenance, and emergency preparedness and response. It also requires records needed to administer those procedures and periodic review and updating of the manuals. The integrity-management provisions require written procedures and records supporting decisions, calculations, changes, justifications and actions.

The practical implication is that an operator cannot close a gap solely by pointing to a paragraph in an O&M manual. The operator must determine whether the requirement is applicable, whether the controlled procedure implements it, and whether the organization can produce the records demonstrating execution.

Why a text comparison is not enough

A basic redline between the first and second editions can help reviewers locate changed language. It cannot answer the operational questions that follow.

Applicability varies

Applicability may depend on storage type, facility characteristics, asset history, activity, operating context and the provisions incorporated through 49 CFR 192.12. State requirements and operator policies may add another layer. A reviewer needs a documented applicability rationale, not merely a list of differences between editions.

Requirements rarely map one-to-one to procedures

One requirement may be implemented through an O&M procedure, a separate integrity-management process, a facility-specific appendix, a training program and a record-retention rule. The gap analysis must preserve those relationships instead of forcing every requirement into a single-document match.

Procedure language is only part of the evidence

A procedure may define what personnel are expected to do, but evidence of implementation may live elsewhere. Depending on the workflow, supporting material might include monitoring records, inspection results, approved calculations, operating-limit tables, work orders, training records, management-of-change documentation or evidence that a prescribed response occurred.

Version errors can produce false assurance

The correct procedure may have been found, but the reviewer may be looking at a superseded revision, a draft or an appendix that does not apply to the facility under review. Every mapping should therefore capture document identity, revision and effective date.

“Not found” does not mean “does not exist”

This distinction is essential. A search may fail because a document was not included in the reviewed corpus, was stored under an unexpected name, was poorly scanned or remains in another system. A defensible result says not found in the reviewed sources and identifies the unresolved evidence request. It does not silently convert a retrieval failure into a compliance conclusion.

A seven-step procedure gap-analysis workflow

01Establish scope and decision authority

Define the facility or facilities, storage type, procedure family, review period and governing sources. Identify who can make applicability decisions and who will approve the final disposition of each finding.

The scope should also state what the review does not cover. Without that boundary, a gap matrix can appear more complete than the underlying review actually was.

02Assemble a controlled source set

Create a source register before starting the analysis. It should include:

• Customer-authorized copies of the applicable standards
• Current federal and state requirements
• Controlled O&M and emergency-response procedures
• Integrity-management plans and supporting procedures
• Facility-specific instructions and appendices
• Referenced forms, tables and operating limits
• Relevant training and qualification materials
• Representative implementation records

Record the owner, revision, effective date and control status of every source. Preserve superseded versions when they are relevant to work performed during earlier periods.

03Build an applicability register

Break the review into individually traceable requirement or obligation records using the operator's authorized copies of the governing sources. Do not publish or redistribute licensed standards content.

Each record should include:

• Source and section reference
• Concise internal description
• Facility and activity applicability
• Applicability rationale
• Required technical or management outcome
• Responsible reviewer

Where applicability is uncertain, classify it as a decision requiring subject-matter review. Do not resolve ambiguity through an automated assumption.

04Map each applicable item to implementation

For every applicable item, identify where the operator implements it. The mapping may include:

• Corporate program or policy
• Controlled procedure and section
• Facility-specific instruction
• Responsible role
• Trigger, limit or decision criterion
• Required record or output
• Training or qualification requirement
• Referenced system or database

The goal is not to maximize the number of document matches. It is to explain the implementation chain clearly enough that another qualified reviewer can follow it.

05Test the supporting evidence

Select representative records appropriate to the scope and ask whether they demonstrate that the mapped process can be executed and verified.

For example, a monitoring workflow might require reviewers to locate:

1. The applicable procedure for the facility and period
2. The relevant operating or response criterion
3. Records covering the required monitoring interval
4. Evidence of any identified exception or exceedance
5. The response prescribed by the procedure
6. Evidence that the response was completed and reviewed

If a required link is absent, the finding should identify the precise evidence gap. A procedure citation alone is not proof that the procedure was performed.

06Assign a controlled coverage status

Use a small, consistently defined status set. One workable model is:

Avoid a single red-yellow-green score without an explanation. A status must be accompanied by source citations, the basis for the classification and any remaining uncertainty.

07Convert findings into governed actions

Each unresolved item should have:

• A specific gap statement
• A proposed corrective action or evidence request
• An accountable owner
• A target date
• Dependencies
• Reviewer and approver
• Final disposition

Compare these two gap statements:

The second statement tells the owner what was reviewed, what was found, what is missing and what must be resolved.

The minimum viable gap matrix

A useful gap matrix should contain at least the following fields:

This matrix becomes more than a spreadsheet when it is maintained as a traceable relationship among requirements, procedures, evidence, decisions and actions.

Where AI can help - and where it cannot

The strongest use of AI in this workflow is not autonomous compliance interpretation. It is reducing the manual work required to assemble and test the review package.

AI-assisted retrieval can help teams:

• Search technical concepts using semantic similarity while retaining exact keyword and identifier search
• Locate cross-referenced procedures, appendices and forms
• Extract searchable information from scans, tables and handwritten legacy records
• Reconcile document names, facility identifiers, well identifiers and dates
• Draft requirement-to-procedure mappings for reviewer validation
• Surface conflicting values and superseded versions
• Identify referenced records that are absent from the reviewed corpus
• Produce source-linked draft findings

But qualified personnel must retain responsibility for:

• Determining applicability
• Interpreting ambiguous provisions
• Deciding whether a procedure is technically adequate
• Resolving conflicting authoritative sources
• Approving corrective actions
• Making legal, regulatory and engineering determinations

An AI system should also expose uncertainty. When evidence is missing, the appropriate result is not a confident answer assembled from the nearest available passages. It is a specific insufficiency statement and a request for the unresolved source.

A practical way to test the workflow

Operators do not need to begin with an enterprise deployment. A bounded proof of concept can test whether the approach improves the quality and efficiency of a real review.

A credible initial scope could include:

• One facility or operating entity
• One procedure family
• A limited, approved document corpus
• A defined subset of applicable requirements or review questions
• Named operator reviewers
• No production-system write access

The deliverables should be agreed before work begins:

• Source and applicability register
• Requirement-to-procedure gap matrix
• Exact document and page citations
• Missing, stale and conflicting evidence log
• Reviewer disposition record
• Evaluation against the operator's current process

Likewise, acceptance criteria should be established in advance. Useful measures include requirement recall, citation accuracy, document-version accuracy, unsupported “covered” conclusions, reviewer acceptance and evidence-assembly time.

The most important measure is the false-clean rate: how often the workflow reports an item as adequately covered when a required procedure or evidence link is actually missing. In a high-consequence technical review, a polished answer with an undisclosed gap is worse than an explicit statement of insufficient evidence.

From procedure comparison to evidence assurance

The second editions of API RP 1170 and RP 1171 create an immediate reason to review UGS procedures, but the durable capability is broader. Operators need a repeatable way to connect changing requirements with controlled procedures, facility context, technical records and accountable decisions.

A well-designed gap analysis provides that foundation. It does not replace the operator's engineers, compliance professionals or legal advisors. It gives them a more complete, traceable and reviewable body of evidence on which to exercise their judgment.

Kataba is developing this evidence-assurance workflow for UGS operators. The starting point is deliberately narrow: one procedure family, one approved corpus, explicit deliverables and acceptance criteria agreed before the work begins.

Have one UGS procedure or evidence workflow worth testing? Discuss a bounded UGS proof of concept.

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Sources

• PHMSA: Pipeline Safety - Standards Update, API RP 1170 and API RP 1171 (opens in new tab)
• Federal Register: Pipeline Safety - Standards Update, API RP 1170 and API RP 1171 (opens in new tab)
• Electronic Code of Federal Regulations: 49 CFR 192.12 (opens in new tab)
• API: Updated Standards for Underground Natural Gas Storage (opens in new tab)
• PHMSA: Underground Natural Gas Storage Facility Safety Site Assessment Summary (opens in new tab)

This article describes a technical review workflow. It is not legal advice, does not reproduce the API standards, and does not make a compliance determination for any operator or facility.