Equipment Piping Process Safety Management

Process safety programs require that all equipment be designed, operated and maintained to the highest standards. In practical terms this requirement means that if the equipment and piping always retains its integrity, i.e., if it does not leak, then then highly hazardous materials will not be released.

Process safety programs often place the management of equipment and piping into the overall category of Asset Management or Mechanical Integrity.

Equipment and Piping Scope

The following is a list of the typical equipment covered by a process safety mechanical integrity program.

  • Pressure Vessels and Columns
  • Storage Tanks
  • Pumps
  • Compressors
  • Turbines
  • Heat Exchangers
  • Air-Cooled Exchangers
  • Cooling Towers
  • Fired Heaters
  • Flares / Blowdown
  • Boilers
  • Internal Combustion Engines
  • Electrical Equipment
  • Buildings
The following is a list of the typical piping and valves that are covered by a process safety mechanical integrity program.
  • Pipe (specifications and sizing)
  • Materials
  • Equipment Piping
  • Fittings
  • Flanges
  • Gaskets
  • Blinds
  • Flame Arrestors
  • Vortex Breakers
  • Hoses
  • Block Valves
  • Globe / Control Valves
  • Rotary Valves
  • Check (Non-Return) Valves
  • Flangeless Valves
  • Valve Seat Materials
  • Valve Position
  • Steam Traps
  • Pressure Safety Relief Valves
  • Thermal Relief Valves
  • Rupture Disks

Regulations, Codes and Standards

There are many regulations, codes and standards to do with the mechanical integrity element of process safety management programs. Some of the key standards-setting bodies are:

  • American Chemistry Council / Responsible Care®
  • American National Standards Institute (ANSI)
  • American Petroleum Institute (API)
  • American Society of Mechanical Engineers (ASME)
  • International Organization for Standardization (ISO)
  • National Fire Protection Association (NFPA)

In the United States important process safety management regulations are published by:

  • The Environmental Protection Agency (EPA)
  • The Occupational Safety & Health Administration (OSHA) 
  • The Bureau of Safety and Environmental Enforcement (BSEE)

Additional Information

Further information and guidance to do with process safety mechanical integrity is provided in the following publications:

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.

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.)

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.

Equipment Isolation Methods

Isolation Methods

Positive isolation methods are those which remain effective even if there is equipment failure or operator error. These techniques apply not only to vessels, piping and tanks but also to pneumatic and hydraulic equipment.

The sketch shows some of the various isolation techniques that can be used to protect workers in the process industries. The process containing toxic or flammable chemicals under pressure is on the left; the open system, where the workers are present, is on the right. The order is from the least to the most secure.

Siting and Layout of Process Facilities

Siting

Siting and Layout: The words ‘siting’ and ‘layout’ are often used interchangeably, but, strictly speaking, they have different meanings. Siting is concerned with the location of a facility. For example, if a company is planning on building a new chemical plant its management may consider the relative merits of sites in Texas, Mexico or China. Layout, on the other hand, is to do with the locations of equipment, piping and buildings at the selected site and how they connect with one another.

Plugged Process Piping

Process lines, piping and valves frequently become plugged. If line pluggage is a recurring problem it is best to try and identify ways in which the problem can be prevented from occurring. If that solution is not possible then valves, drains, tees and connections should be designed so that it is possible to remove the pluggage safely and with minimum time and expense.

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.