Pumps & Systems, March 2007
Many pipeline systems throughout the U.S. are in need of maintenance, but this maintenance is often pushed back because there is no way to properly shut down the system. Not any more. Time to gain control of your system.
The inability to isolate sections of pipeline for repair and maintenance is a growing problem today due to aging infrastructures and increasing numbers of inadequate or broken valves.
How many times have you had your service crews called out in the middle of the night or on a holiday? How many of those service calls were due to pipeline maintenance or repair that was delayed because you did not have control of your system? Not having a way to isolate sections of your pipeline without complete system shutdown is often the reason why you don't have control of your system.
So How Do You Take Control?
There are many inherent risks associated with system shutdown: boil orders, contamination, water hammer, and loss of fire protection, to name a few. Many systems only know of two ways to perform maintenance and repairs to their pipeline: either shutdown or perform the maintenance/repairs live. By attempting to perform these repairs live, a number of other liabilities occur, which can result in unsafe working conditions for the operator.
As regulations continue to become more stringent, there is another more cost effective way to perform routine or emergency maintenance and repairs to pipelines without the risk. Line stopping and live valve insertion isolates the section of pipe in need of repair while keeping the system live, resulting in the ability to do the required repair or maintenance without the risk. This puts you in control of your system.
Integrated pipeline maintenance equipment allows you to perform tapping, line stopping, and valve insertion. These processes allow connection to or isolation of your pipeline without system shutdown. When you take into consideration all of the costs associated with shutting down a system, such as overtime, advertising the shutdown, locating and turning valves, and compliance with rules and regulations, you will find the following processes to be more economical.
Line stopping is simply tapping with the addition of flow stopping. To perform a line stop, a line stop fitting (which is similar to a tapping sleeve), a temporary valve, and integrated pipeline maintenance equipment is all that is needed. Pipeline variables such as flow, pressure, size, and type will indicate which line stopping head should be used. There are several types of line stopping heads that can be used in different applications.
A stop head, which is a flexible rubber stopper that looks like a deformable cork, easily handles moderate pressures and tuberculated lines in pipe sizes up to 12-in and pressures up to 100-psi. A bullet head is used in higher pressure systems and in bypass scenarios up to 20-in and pressures up to 250-psi. Both of these heads are a good option for contractors and municipalities because utilization of these heads is easy.
When considering larger diameter line stops, pivoting heads are most commonly used. Folding heads are used when line stopping is needed for concrete cylinder pipe. The folding head enables entry into the pipe through a tap two nominal sizes smaller than the pipe's inside diameter.
When isolating sections of pipeline, more than one line stop is often needed. When performing a double line stop, there are two methods of isolation while keeping the pipeline in service. When working within a looped distribution system, two line stops are simply performed and, as a result, the pipeline in need of repair or maintenance is isolated without service disruption. Bypass stopping is used when pipeline maintenance or repair is needed on transmission mains or force mains. Bypass line stopping allows the flow to be rerouted through the equipment.
Live valve insertion is just as simple with an insertable temporary valve system. These do not involve reaming, cutting below the spring-line, or losing excessive pipe strength. The equipment is similar to a tapping sleeve that provides the ability to insert a valve anywhere in the system, in the open position, without shutting the system down. The technology is easy to learn and utilizes the same tapping technology that has provided decades of reliability. Such equipment can be purchased as stand alone or as a kit that adapts to an existing system.
Three of the main costs associated with system shutdown can be avoided when choosing an integrated pipeline maintenance option:
- Loss of revenue (while the system is shutdown), which includes the costs associated with loss of treated water as the line drains.
- Maintaining compliance with national, state, and local regulations when shutting the system down is costly. In many cases, regulations will require issuing a boil order, sampling, lab costs, and rechlorinization.
- Potential costs of litigation and associated political ramifications are also a common concern and reality with system shutdowns.
Integrated pipeline maintenance equipment can be (1) purchased and received on-site, with the manufacturer providing factory training; or (2) pipeline maintenance contract services can be purchased from the manufacturer, who then performs the work. The following two cities provide examples of each option.