Your PSM Program Is Only as Good as Your Process Safety Information | Blog No. 138

Process Safety Information (PSI) is the technical foundation of a Process Safety Management (PSM) program. Your PHAs, operating procedures, mechanical integrity program, and many other PSM activities depend on this information being accurate.

Under OSHA 29 CFR 1910.119(d), PSI is divided into three main categories. But what actually belongs in each one?

1. Hazards of the Chemical

For an ammonia refrigeration system, this section documents the hazards and properties of anhydrous ammonia. OSHA identifies seven subelements:

• Toxicity information

• Permissible exposure limits

• Physical data

• Reactivity data

• Corrosivity data

• Thermal and chemical stability data

• Hazardous effects of inadvertent mixing

  
  

Much of this information can typically be found within the facility's Safety Data Sheet (SDS) and supporting technical references.

2. Technology of the Process

This section describes how the refrigeration process is intended to operate. It includes:

• Block Flow Diagram or simplified Process Flow Diagram

• Process chemistry

• Maximum Intended Inventory (MII)

• Safe upper and lower limits

• Consequence of deviations

  
  

For an ammonia refrigeration facility, this information establishes the basic operating boundaries of the system.

Knowing that your high discharge pressure limit is 200 psig is useful. Knowing why that limit exists and what can happen when you exceed it is what makes that information valuable.

3. Equipment in the Process

The final category documents how the physical refrigeration system is designed. OSHA identifies:

• Materials of construction

• Piping and Instrumentation Diagrams (P&IDs)

• Electrical classification

• Relief system design and design basis

• Ventilation system design

• Design codes and standards employed

• Material and energy balances for processes built after May 26, 1992

• Safety systems

  
  

For many ammonia refrigeration facilities, this is where a significant portion of the engineering documentation lives.

It is also where outdated information can quickly become a problem.

A facility may have P&IDs, but do they match what is actually installed? You may have a relief analysis, but has the piping or equipment changed since it was completed? You may have documented safety systems, but do the listed setpoints match the controls in the field?

Having PSI Isn't Enough

The purpose of PSI isn't simply to have documents in a binder or uploaded into a PSM software system.

The information needs to represent the refrigeration system that is actually operating.

That matters because PSI feeds directly into the rest of the PSM program. PHAs rely on accurate P&IDs and operating limits. Operating procedures rely on the correct system configuration. Mechanical integrity relies on accurate equipment information. Management of Change helps keep that information current when modifications are made.

So, when reviewing your PSI, don't just ask:

"Do we have it?"

Ask:

"Is it accurate?"

Because your PSM program is only as good as the information it is built on.

Previous Blog: Valve Flow Arrows | Blog No. 137

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