An industrial piping system is a network of pipes used to transfer liquid, gas or solids from one location to another, with close to zero loss of the quality or properties of the material being transferred. The most common material to be moved in an industrial piping system is water, either as a liquid or as steam. Other common materials include fuel, ammonia, and compressed gases such as air, oxygen, and nitrogen.
Industrial piping systems include those in oil refineries, chemical production facilities, power plants, and even those used in smaller facilities such as fabrication and machine shops. Industrial piping system does not include those in commercial buildings, nor long distance pipelines.
Inspection and maintenance of industrial piping systems can often be neglected because pipes seem to accomplish their intended purpose with little care. However, inspections, maintenance, and repair are needed, and when this type of work is being done, that's the most likely time for a serious accident.
Catastrophic pipe failures, particularly those in oil refineries, make the news and grab the public's attention. But, catastrophic failures are rare. Industrial piping systems are most dangerous during normal, routine inspections or maintenance, and the danger usually comes from human error.
Industrial Piping Systems Are Closed Systems
It's important to recognize that an industrial piping system is a "closed system" and that working on a closed system does not always ensure safety. The opening of valves, turning on pumps, or working on equipment that is not isolated or locked/tagged out are significant sources of hazards. In addition, when a normally closed system is opened, there is the potential for serious hazards, if the necessary precautions are not taken.
The following are examples of actual accidents involving industrial piping systems:
- In 2006 a worker was removing a pipe cap from an eight-inch pipe that was pressurized with 80-pounds of air. The worker was not aware the pipe was pressurized. As it was loosened the metal pipe cap blew off the end of the pipe, striking and killing the worker.
- On February 29, 2012 four people were using a cutting torch to demolish an out-of-service petroleum pipe. The pipe had not been purged in over a year. It contained vapors that resulted in an explosion and flash fire. All four workers were scalded, burned, and taken to the hospital. Two were released after 24 hours; the other two remained hospitalized for an extended period of time.
- Two workers were operating a sodium turn state purification system. When attempting to pump a sodium sulfhydrate solution into a tank, one of the workers accidentally opened the valve to another tank which contained an acidic solution. When the two chemicals mixed they produced hydrogen sulfide gas. The worker died from exposure to hydrogen sulfide gas.
- In another fatality involving hydrogen sulfide gas, a worker accidentally drained the contents of a knockout drum to an oily water sewer, rather than to a closed system. This produced hydrogen sulfide gas resulting in the fatality. The draining procedure required the use of the closed system, however, the valve to the sewer was not closed and locked out before he started draining the knockout drum.
- Workers were draining refrigerant oil from collection traps on an anhydrous ammonia refrigeration system. The workers were using hand tools to open the valves and drain off the oil, when they were heavily exposed to anhydrous ammonia, resulting in two fatalities.
- A worker was killed as he was disconnecting a pipe from an ammonia valve. The pipe had not been properly isolated and locked out, and still contained ammonia under pressure. As the pipe was disconnected the liquid ammonia was released, striking the worker's face and body.
- Equipment, such as heaters used in an industrial piping system can also be a source of hazards, if proper lockout procedures are not followed. An accident occurred when a worker was changing an O-ring in a line heater. He had closed the valve upstream of the heater but, contrary to the required procedure, had not closed the downstream valve. As he was loosening it the end blew off the pipe, and struck and killed the worker. The average pressure in this system at the time was 8,500 psi.
- Not all industrial piping system injuries result from human error. On September 27, 2010 a worker was returning an eight-inch steam header back into service after planned maintenance. The worker, along with three coworkers, was walking along the steam header catwalk checking the valve positions. A two-inch, 90 degree elbow suddenly failed resulting in 1,000 psi, 500 to 650 degree Fahrenheit steam discharging onto the first worker. He was hospitalized for second and third-degree burns over 80 percent of his body.
Common Factors In Industrial Piping System Accidents
A common cause of accidents related to industrial piping systems is that the system is opened as a result of opening a valve, cutting, or venting, with the result being a fatality caused by the unexpected release of the pipe contents. To prevent these types of accidents, the following are recommended:
- Conducting a process hazard analysis to address the hazards of the process, and then using engineering and other control measures to ensure worker safety. The analysis should include a complete evaluation and assessment of the industrial piping systems that are a part of the process.
- Establishing written lockout/tagout (LOTO) procedures, and assuring they are followed. A piping system must be under LOTO, and all lines and equipment must be drained and purged before any work on a piping system is started.
- Ensure that all pipes and valves are properly and clearly labeled, including any necessary warning messages. Information labels and signs should be used to remind workers about required shutdown, LOTO, and general safety procedures.
- Establish written procedures, verify those procedures are clear, and test the procedures to ensure they provide complete instructions for the safe performance of the work activities.
- Be sure that all employees, including contract employees and vendors, are trained in the required procedures and safe work practices, and that they understand and adhere to the current operating procedures of the process.
While the risk of industrial piping system accidents cannot be entirely eliminated, following the above requirements and practices will reduce the potential for an accident.
The Importance of Effective Pipe Markers for Industrial Piping Systems
Pipe marker labels and valve tags provide critical information about pipe contents, the direction of flow, and the type of hazard presented by the pipe contents. They may also include information such as temperature and pressure. Valve tags identify the valve, and can contain information about their function in the process. Other components of an industrial piping system such as flanges, vents, drains, and instrument connections should also be labeled for easy identification. When workers are fully informed, they are safer and can do a better job.
Industrial Pipe Systems Training
All employees should receive regular training in the safety procedures related to their job. In addition, they should know about other aspects of the industrial piping systems they are working on. For example, maintenance workers should have some familiarity with the operation of the processes.
Following the training, an evaluation of the effectiveness of the training should be done by observing people as they work, and additional on-the-job or formal training classes should be provided as needed.
Respirators must be provided by the employer when there is a chance of an exposure to airborne hazards, and training in the use of the respirators must be provided. The employer must provide respirators that are applicable for the intended purpose. Written procedures must be developed for the safe use of respirators during the performance of work that potentially exposes workers to a hazardous chemical.
Under circumstances where individuals may be exposed to an unknown concentration of hydrogen sulfide, or other hazardous chemical, back-up personnel with appropriate respirators and emergency equipment must be present.