Format for Alarm and Trip Settings document in oil and gas sector

An Alarm and Trip Settings document, often called an Alarm and Trip Schedule or Cause and Effect Matrix, is a critical engineering document in the oil and gas industry. It formally records all the setpoints for process alarms and automated trips (shutdowns) for a facility.

The format is typically a detailed table or spreadsheet supplemented by several key sections that provide context, definitions, and control procedures.

## 1. Cover and Revision History Page

This initial page includes:

• Project Name/Facility Name: Identifies the plant or unit.

• Document Title: “Alarm and Trip Settings” or similar.

• Document Number: A unique identifier for document control.

• Revision History: A table tracking changes, including the revision number, date, description of changes, and approvers’ signatures.

## 2. Introduction

This section briefly explains the document’s purpose, which is to define the alarm and trip setpoints for the process and utility systems to ensure safe and reliable operation. It outlines the scope and intended audience (e.g., operations, maintenance, and engineering personnel).

## 3. Definitions and Abbreviations

A crucial section to ensure clear understanding. It defines key terms and lists all abbreviations used throughout the document.

Common Definitions:

• Process Variable (PV): The measured process parameter (e.g., pressure, temperature, level, flow).

• Setpoint: The predefined value at which an alarm or trip is activated.

• Alarm: An audible and/or visible signal indicating a deviation from normal operating conditions.

• Trip: An automated protective action that initiates a shutdown of equipment or a system to prevent a hazardous event.

• Interlock: A type of trip that prevents an unsafe action from occurring or shuts down equipment in a specific sequence.

## 4. References

This section lists all documents and standards that the Alarm and Trip Settings are based on. This often includes:

• Piping and Instrumentation Diagrams (P&IDs)

• Process Flow Diagrams (PFDs)

• Control Narratives

• Hazard and Operability (HAZOP) Study reports

• Safety Integrity Level (SIL) Assessment reports

• Relevant industry standards (e.g., API RP 14C, ISA-18.2)

## 5. Alarm and Trip Schedule (The Core Table)

This is the heart of the document, typically presented as a detailed spreadsheet. Each row corresponds to a specific instrument or control loop, and the columns detail the settings.

Typical Columns in the Schedule:

• Tag Number: The unique identifier for the instrument (e.g., PT-101A).

• P&ID Number: The drawing where the instrument is located.

• Service Description: A brief explanation of the instrument’s function (e.g., “Compressor K-101 Suction Pressure”).

• Normal Operating Range: The expected range of the process variable during normal operation (e.g., 50-60 barg).

• Units: The unit of measurement (e.g., °C, barg, %, m³/hr).

• Alarm Setpoints:

  • L (Low): Low alarm setpoint.

  • LL (Low-Low): Low-low alarm/trip setpoint.

  • H (High): High alarm setpoint.

  • HH (High-High): High-high alarm/trip setpoint.

• Trip Setpoint: The specific value that triggers an automatic shutdown action. This is often the same as the HH or LL setpoint.

• Time Delay (sec): The duration a condition must persist before the alarm or trip is activated, preventing nuisance alarms from transient fluctuations.

• Action/Consequence: A clear description of what happens when a trip is activated (e.g., “Shuts down Compressor K-101”).

• Alarm Priority: The assigned priority of the alarm (e.g., High, Medium, Low) based on the severity and time to respond, as defined in the Alarm Philosophy document.

• Remarks: Any additional notes, such as the basis for the setpoint (e.g., “HAZOP recommendation #3.2”).

## 6. Management of Change (MOC)

This section outlines the formal procedure required to make any changes to the approved alarm and trip settings. It mandates that any modification must be reviewed, documented, and approved by a multidisciplinary team to ensure safety and integrity are not compromised. Unauthorized changes are strictly forbidden.