Safeguarding our piping (ASME B31.3, Appendix F)

Safeguarding is the provision of protective measures to minimize the risk of accidental damage to the piping or the harmful consequences of possible piping failure.  In most instances, the safeguarding inherent in the facility (the piping, the plant layout, and its operating practices) is sufficient without the need for additional safeguarding. 

In some instances, however, engineered safeguards must be provided.

Where safeguarding is required by the Code (ASME B31), it is necessary to consider only the safeguarding that will be suitable and effective for the purposes and functions stated in the Code or evident from the designer’s analysis of the application.

In evaluating a piping installation design to determine what safeguarding may exist or is necessary, the following should be reviewed:

1. The hazardous properties of the fluid are considered under the most severe combination of temperature, pressure, and composition in the range of expected operating conditions.
2. The quantity of fluid that could be released by piping failure, considered in relation to the environment, recognizing the possible hazards ranging from large
   releases of otherwise innocuous fluids to small leakages of toxic fluids.
3. Expected conditions in the environment will be evaluated for their possible effect on the hazards caused by a possible piping failure. This includes consideration of ambient or surface temperature extremes, degree of ventilation, proximity of fired equipment, etc.
4. The probable extent of operating, maintenance, and other personnel exposure, as well as reasonably probable sources of damage to the piping from direct or indirect causes.
5. The probable need for grounding of static charges to prevent ignition of flammable vapors.
6. The safety inherent in the piping by virtue of materials of construction, methods of joining, and history of service reliability.

Safeguarding by Plant Layout and Operation

Representative features of plant layout and operation that may be evaluated and selectively utilized as safeguarding include:

1. plant layout features, such as
   1. open-air process equipment structures,
   2. spacing and isolation of hazardous areas,
   3. slope and drainage;
   4. buffer areas between plant operations and populated communities, or
   5. control over plant access
2. protective installations, such as
   1. fire protection systems;
   2. barricades or shields;
   3. ventilation to remove corrosive or flammable vapors;
   4. instruments for remote monitoring and control;
   5. containment and/or recovery facilities; or
   6. facilities (e.g., incinerators) for emergency disposal of hazardous materials
3. operating practices, such as
   1. restricted access to processing areas;
   2. work permit system for hazardous work; or
   3. special training for operating, maintenance, and emergency crews
4. means for safe discharge of fluids released during pressure relief device operation, blowdown, cleanout, etc.
5. procedures for startup, shutdown, and management of operating conditions, such as
   1. gradual pressurization or depressurization, and
   2. gradual warmup or cooldown, to minimize the possibility of piping failure, (e.g., brittle fracture)

Engineered Safeguards

Engineered safeguards that may be evaluated and selectively applied to provide added safeguarding include

1. means to protect piping against possible failures, such as
   1. thermal insulation, shields, or process controls to protect from excessively high or low temperatures and thermal shock
   2. armor, guards, barricades, or other protection from mechanical abuse
   3. damping or stabilization of process or fluid flow dynamics to eliminate to minimize or protect against destructive loads (e.g., severe vibration pulsations,
      cyclic operating conditions)
2. means to protect people and property against harmful consequences of possible piping failure, such as confining and safely disposing of escaped fluid by
3. shields for flanged joints, valve bonnets, gages, or sight glasses; or for the entire piping system if of frangible material; limiting the quantity or rate of fluid escaping by automatic shutoff or excess flow valves, additional block valves, flow-limiting orifices, or automatic shutdown of pressure source; limiting the quantity of fluid in process at any time, where feasible.