Pipeline Leak Detection: Understanding Incident Levels and Sensitivity Criteria
Introduction
Pipeline leak detection is essential to ensure the safety of both the environment and the people who are responsible for its operations. The American Petroleum Institute (API) has developed a Recommended Practice, API 1130/1155, which outlines the sensitivity criteria for detecting liquid spills in pipelines. This document will discuss the criteria for both liquid and gas pipelines, taking into account the different measurements used for each.
What is API 1130/1155?
The API 1130/1155 Recommended Practice outlines the sensitivity criteria for detecting liquid spills in pipelines. The practice defines pipeline leak detection sensitivity as a two-dimensional concept in terms of a series of “sensitivity curves” that represent the “spillage volume”, which are dependent on “spillage flow rate” and “time” under different operating conditions. In turn, the spillage flow rate is also a factor of many parameters such as pipeline diameter, operating pressure, and the type of fluid.
Incident Levels and Leak Sensitivity Definition for Liquid
The specification document states that the “Incident Level Minor” of 1000 barrels per 8 hours is the basis for all other performance criteria. The document further states that the leak system should be installed to detect a leak of spill size less than 1000 BBL (Minor level), with the spill flow rate and the time not exceeding the minor incident level spill quantity. The time to stop the leak is divided between mobilization time, repair time, and leak detection instrument response time.
Gas Pipeline Leak Detection
Since gas is a pressurized substance with varying volume under different pressure conditions, the industry has selected SCF (standard cubic foot) as the proper measure for gas quantity, and MMSCFD (million standard cubic foot per day) as the proper measure for gas flow rate. Therefore, this specification provides leak detection criteria based on detected spilled volume for liquid (oil, NGL, and other liquid products), and provides leak detection criteria based on MMSCFD (or percentage of it) for gas products, taking into account pipeline dimensions and operating conditions.
Conclusion
Pipeline leak detection is essential to ensure the safety of both the environment and people responsible for its operations. The American Petroleum Institute (API) has developed a Recommended Practice, API 1130/1155, which outlines the sensitivity criteria for detecting liquid spills in pipelines. This document discussed the criteria for both liquid and gas pipelines, taking into account the different measurements used for each. Furthermore, the document states that the “Incident Level Minor” of 1000 barrels per 8 hours is the basis for all other performance criteria.