
Pipelines Demand Pre-incident Planning
ON HAZARDOUS MATERIALS
As I discussed in last month’s column, pipeline incidents can create a major problem for the fire service. In the event of a pipeline rupture, the large quantities of product under high pressure can have a devastating effect on the area surrounding the break. Major fires can result and severe injuries very often occur. To illustrate the problems which can be experienced, I am going to discuss an incident which occurred in Ackerly, Texas, in 1981.
A construction crew was preparing ♦in oil well site in the middle of a cotton field and constructing an access road to the site. A large hole had been dug where the drilling rig would be located. A pad was installed to provide a smooth, hard, level surface on which to operate. At the time of the incident, there were five people working at the well site, one person working nearby, and six people driving dump trucks with the road material.
A drilling rig was brought to the site to drill holes in three predetermined places. Besides the drill operator, there was an assistant who kept the cuttings away from the hole.
The pipeline dispatcher and monitor were located in Tulsa, Okla. The sudden release of the product caused a drop in pressure on the pipeline, and the automatic alarms were activated in the Tulsa control facility.
Just as a series of pumpers is necessary to move water over a distance, so must a pumping station be spaced along the pipeline. In this case, they were between 50 and 100 miles apart. The closest pumping stations were: Ackerly station, unmanned, 4 miles downstream of the accident; Snyder station, unmanned, 99 miles downstream of the accident; and San Andres station, manned, 46 miles upstream of the accident.
The time sequence for this incident graphically illustrates the problem in handling a pipeline incident. Even if the information (location, product) on the break is known immediately, shutdown takes time. In addition, since only those valves at the pumping station can be closed remotely, only a 50 to a 100-mile section of the pipe can be isolated. As a result, the ethane-propane mixture from the 12 inches of pipe times 50 miles in length would have to leak out before the fire could be extinguished.
The specific time sequence for this incident was:
1:38—alarm indicating low pressure received in Tulsa from the Ackerly station.
1:40—manned station at San Andres confirms a drop in pressure.
1:40—low pressure signal received from the unmanned Snyder station.
1:41 —operator remotely closes intake valve at the Ackerly station.
1:42—technician on call sent to Ackerly station.
1:44—personnel at the San Andres station instructed to shut down main line pumps and divert product to storage wells.
1:47—main line pumps are shut down at San Andres.
1:52—operator remotely shuts down pump at Snyder station.
2:14—operator attempts to close main line valve at Ackerly station but valve won’t close.
2:22—operator closes main line block at Snyder station.
2:45—an individual within 1 mile of the break calls for control operator in Tulsa and requests permission to close the manual valves at the Ackerly station. Permission is granted and the break is isolated to a 5-mile segment of the pipeline. One hour and seven minutes after the accident, the 5-mile segment of the break was finally isolated, and with the closing of this valve the fire rapidly died.
As a result of the fire, three people working at the well site were killed immediately and a fourth critically burned individual died four days later. In addition, the drilling rig, a pickup truck a road grader, a compactor and over 535,000 gallons of the ethanepropane mixture were destroyed. Finally, more than 60 acres of cotton were burned in the ensuing fire.
The product being moved through the pipeline was a mixture of 70 percent ethane and 30 percent propane. A liquid at 574 psig and 60°, once the product is released to the atmosphere, expands at 277 parts gas to 1 part liquid and creates a vapor cloud as it refrigerates the moisture in the air. The product is also heavier than air, so it remains near the ground and can travel easily to a remote ignition source.
The lessons learned from this particular incident are:
- Preplan the location of pipelines in your area.
- Determine the products that are carried in the pipelines in your area and learn their characteristics.
- Plan alternate routes to the scene in case your primary one is blocked.
- Learn where the manual closure valves are located and work with the pipeline company to develop procedures for determining who needs to be contacted before closing one. Preincident planning and cooperation may result in training the fire department to shut down the valve immediately on report of a confirmed leak.
- Develop emergency medical plans for handling the potentially large number of injuries from a pipeline incident.
- Locate water supplies. Even if your entire area has a pressure system, find your drafting sources in case the explosion damages the water mains.
- Be prepared to fight structural fires and other exposure fires for a long period of time until the pipeline can be shut down.
- Notify the pipeline company of any construction activity in the vicinity of a pipeline.
- Plot the locations of the pipelines on a map of the area so that nearby exposures can be determined.
- Develop an evacuation plan for residents of the potential exposures.
- Train mutual-aid companies concerning the location and operation of all parts of the pipeline system and the correct procedures for handling an incident. Make sure that they are familiar with the support your department will need.
- Determine where you will get immediate weather information, particularly wind direction.
- Preplan the topography in your area, giving particular attention to low areas containing life and/or unusual ignition sources.
Planning is the key to successfully handling a pipeline incident. Don’t let it catch you by surprise.