The following articles provide information to do with the operation, maintenance and inspection of process facilities.

Types of Maintenance

Process Safety Maintenance

Maintenance work usually falls into one of the following four categories:

  1. Repair;
  2. Condition-based maintenance;
  3. Scheduled maintenance; and
  4. Reliability-centered maintenance (RCM).

All but the first of these can be placed in the overall category of preventive or preventative (either spelling is acceptable) maintenance.

Catching Samples

The material in this post is extracted from the 2nd edition of the book Plant Design and Operations.

Dedicated connections should be provided for sample collection. Sample take-off connections should be easily accessible and should be at ground level. The sample line should be as short as possible. If it cannot be made short then a sample loop, as described below, will be needed. Sample take-off connections should never be located at dead ends of piping.

Stairways and Ladders

The material in this article is extracted from Chapter 2 of the 2nd edition of book Plant Design and Operations.

When developing the layout for a facility it is very important to ensure that personnel can move around quickly and safely using stairways, ladders, platforms and ramps. They should also be able to use the stairways and ladders to move maintenance equipment and tools, as needed and also to evacuate the facility during an emergency.

Safety Signs

The material in this Article is extracted from Chapter 16 (Human Factors and Ergonomics) of the book Plant Design and Operations.

Guidance as to the types of signs and their meanings is provided below.


Prohibition signs mean "You must not" or "Do not do . . ." or "Stop". Signs of this type have a red circle, a white interior and a red bar, as illustrated in Figure 16.4.

Figure 16.4
Prohibition Sign

Lockout Tagout

Lockout / tagout systems are routinely used to protect workers when they are working with or close to hazardous systems. They are typically used in conjunction with the other isolation methods. Once a switch or valve is in the correct position it is locked so that it cannot be moved, and a 'Do Not Operate' tag is attached to it. (Valves are often chained in place, with the lock being used to secure the chain such that the valve handle cannot be moved.)


Human error rates can be modeled using a technique known as THERP (Technique for Human Error Rate Prediction). The method uses Boolean logic to model and predict human error rates. Hence it can be integrated Probabilistic Risk Assessment techniques - particularly Fault and Event Tree analysis.

Confined Space Entry

Confined Space Entry

A Confined Space is a space which is large enough for a worker to enter but has limited openings for entry and exit and is not intended for continuous employee occupancy. Entry is considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space. Therefore it is not permissible, for example, to take a quick breath and to put one's head into a vessel for a quick look without having an entry permit.

Storage Tanks in the Process and Energy Industries

Storage tanks are widely used in the process industries to store liquids that are below their boiling point at atmospheric temperature (some tanks may be insulated and they may have heating or cooling coils to maintain the temperature of the liquid that they are storing). Typically, tanks are either open to the atmosphere or to a system such as a flare or vent header that is at atmospheric pressure (this does not apply to floating roof tanks). Unlike pressure vessels, storage tanks cannot handle either high pressure or vacuum conditions.