Key takeaways
- API RP 1130 covers computational pipeline monitoring (CPM) on liquid pipelines. It is a recommended practice, and it becomes binding where a regulation or contract adopts it.
- API RP 1175 covers the leak detection programme as a whole, across every method, not just CPM software.
- 49 CFR 195.444 is the US rule for hazardous liquid pipelines. It requires an effective leak detection system, and CPM systems must follow API RP 1130 in operation, maintenance, testing, record keeping and training.
- RP 1130 is not a product certification scheme. Compliance is shown by documented design, testing and operating records for the pipeline in question.
Three documents, three jobs
Operators, consultants and suppliers often say “API 1130 compliance” as if it were a single yes-or-no property. In practice three documents are involved, and they do different things.
| Document | What it is | What it covers | Binding? |
|---|---|---|---|
| API RP 1130 | Recommended practice (industry standard) | Design, implementation, testing and operation of computational pipeline monitoring on liquid pipelines | Only where a regulation or contract adopts it |
| API RP 1175 | Recommended practice (industry standard) | Managing a leak detection programme across all methods: selection, performance, testing, people and improvement | Guidance unless a regulator or contract makes it a requirement |
| 49 CFR 195.444 | US federal regulation | Leak detection on hazardous liquid pipelines, including how CPM systems must be operated | Yes, for pipelines within its scope |
RP 1130 is written for liquids. Gas pipelines are outside its scope.
API RP 1130: computational pipeline monitoring
Computational pipeline monitoring is the family of software methods that help a pipeline controller recognise hydraulic anomalies that could indicate a leak: mass balance, real-time transient modelling, statistical analysis and pressure-wave detection among them. API RP 1130 covers how such systems are designed, implemented, tested, operated and maintained on liquid pipelines. It replaced the earlier API 1155.
One of its most useful contributions is a shared vocabulary for performance. It describes four measures, and they work as the basis for specifying and acceptance-testing a system:
- Sensitivity. The size of leak the system can detect and how long it takes to alarm.
- Reliability. How often the system makes correct decisions, which includes keeping false alarms low.
- Accuracy. How well it estimates leak parameters such as rate, volume lost and location.
- Robustness. How well it keeps working, and keeps providing useful information, when conditions change or data are lost or suspect.
The four pull against each other. Pushing for sensitivity usually costs reliability, because a system tuned to catch smaller leaks sooner will alarm more often on noise. A specification that quotes a leak size and a time without a false-alarm expectation and a robustness requirement leaves most of the real design question open.
API RP 1175: managing leak detection as a programme
RP 1130 asks whether a CPM system has been designed, tested and operated properly. API RP 1175, Pipeline Leak Detection: Program Management, asks a wider question: is the whole leak detection effort proportionate to the pipeline’s risk, and is it managed over time?
It applies across every method an operator uses, not only software. It gives a framework for choosing technologies and systems to suit the pipeline, setting performance goals, testing, training people and improving the programme as experience builds. The second edition adds the role of fibre optic sensing, reflecting how external methods are now used alongside CPM. That is the layered approach we describe in RTTM vs fibre optic leak detection.
49 CFR 195.444: the US regulation
49 CFR 195.444 applies to hazardous liquid pipelines regulated in the United States by the Pipeline and Hazardous Materials Safety Administration (PHMSA). It requires an effective leak detection system, with the adequacy of the system assessed against factors such as pipeline length and size, product type, how quickly leaks can be detected and leak history.
It also reaches into the standard. A CPM leak detection system on a pipeline carrying a single-phase liquid must comply with API RP 1130 in operating, maintaining, testing, record keeping and training dispatching personnel. That is how a recommended practice becomes a legal obligation: the regulation adopts it for the activities it names.
Regulations are amended, so check the current text on the Electronic Code of Federal Regulations before relying on this summary.
Outside the United States
Requirements differ from country to country. Many regulators and operators treat API RP 1130 and API RP 1175 as accepted practice even where no law mandates them, and some regions set their own technical rules. Our Karbala Refinery leak detection project in Iraq was delivered against API 1130 and TRFL guidelines, for example.
The practical step is to check with the regulator, the client specification and the operator’s own standards which documents apply, and to write that into the design basis before design starts.
What “compliant” should mean in practice
Because RP 1130 is not a product certification scheme, no certificate makes a system “API 1130 compliant”. Compliance is demonstrated for a particular pipeline, through evidence. The records a client, auditor or regulator is likely to ask for include:
- A design basis. Pipeline data, instrument list, fluid properties and the performance targets, stated in terms of sensitivity, reliability, accuracy and robustness.
- Test results. Acceptance testing that shows the system detects leaks as specified, and that it stays quiet through normal operation.
- Operating procedures. What controllers do on an alarm, and how leak and non-leak events are logged.
- Maintenance and calibration records. Instruments, models and communications kept in the condition the design assumed.
- Training records. Evidence that dispatching personnel understand the system and the response.
- Change control and re-testing. A way to show that the system still performs after the pipeline, the product or the instrumentation changes.
When you evaluate a supplier, ask how they would produce this evidence for your pipeline, not whether they hold a certificate.
Common misunderstandings
- “API RP 1130 is a law.” It is a recommended practice. It binds only where a regulation such as 49 CFR 195.444, or a contract, adopts it.
- “It applies to gas pipelines.” It is written for liquid pipelines.
- “Having a leak detection alarm means being compliant.” The standard is about performance, testing, operation and records, not the presence of an alarm.
- “RP 1130 covers fibre optic and other external methods.” It covers computational pipeline monitoring. External methods sit in the wider programme that RP 1175 addresses.
Our leak detection systems are designed with these documents in mind, and our pipeline management systems bring the results into one operator environment. This article is general engineering information, not legal advice. Check the current text of each document and the rules that apply to your pipeline, or talk to our team.
Frequently asked questions
Is API RP 1130 mandatory?
In itself, no: it is a recommended practice. In the United States, 49 CFR 195.444 makes it binding for CPM systems on hazardous liquid pipelines carrying single-phase liquid, covering operation, maintenance, testing, record keeping and training of dispatching personnel. Elsewhere it depends on the regulator and the contract.
What is the difference between API RP 1130 and API RP 1175?
API RP 1130 deals with computational pipeline monitoring systems themselves: how they are designed, tested and operated. API RP 1175 deals with the leak detection programme as a whole, across all methods, together with the people and processes around it.
Does API RP 1130 apply to gas pipelines?
No. It is written for liquid pipelines. Gas pipelines are covered by other regulatory frameworks and guidance, although concepts such as mass balance and transient modelling apply there too.
Can a leak detection product be certified as API 1130 compliant?
RP 1130 is not a product certification scheme. Conformity is shown for a specific pipeline through a documented design basis, test results, operating procedures and maintenance, calibration and training records.
