Perfect piping will probably be forever elusive and pipe leaks will likely be with us always. Predictability of problems has been greatly enhanced via non-destructive testing such as audio gauging, X-ray, magnetic particle inspection and a variety of sensors and "listening" devices. Since these highlight potential problems, maintenance personnel can anticipate the eventuality and either make repairs on that discovery or inventory the tools used to deal with the problem so they will be readily accessible. The inspection devices are valuable tools; however, they are still just indicators of problems and not precise for timing purposes. Leaks are thus an eternal nuisance and a single event can result in the loss of life and millions of dollars. That potential demands perpetual surveillance of all piping systems. When piping options were few, extensive wear with certain fluids was inevitable. Corrosive or high solid slurries took a relentless toll. The great variety of piping materials today provide more durable answers to these historical problems. But even with these advancements, the basic causes of leaks have really not changed. Design, installation and monitoring do minimize the frequency of incidents, but total replacement of failed segments remains the primary and preferred solution when leaks do occur. The cost and untimeliness of total replacement solutions suggest alternative methods of repair.
The news media feeds voraciously on pipe leaks in plant operations and spills on shore and offshore. Problems range from creation of a hazardous work place to critical and more life threatening concerns created in explosive and poisonous atmosphere, as well as environmental damage.
Strict adherence to the emergency safety measures is primary. Depending on the event, that can mean immediate shut down of the system, controlled ventilation, containment steps and/or other actions dictated by the particular fluid involved. Some accidents may be unavoidable, but they can be Minimized by contingency planning. When they do occur, management is obligated to control and manage these events with the best tools available at the time. Anticipation of potential leak problems is the key for developing an appropriate inventory of tools that must be maintained on hand to deal instantly with leaks. Most pipe leaks can usually be attributed to one or more of the following:
- Pinhole leaks caused by corrosionexposure of unprotected steel to the environment, electrolytic corrosion caused by other lines in the proximity and corrosive fluids in the transmission line;
- Bad weld joints in metal pipe or fusion welded plastics;
- Poor seals in threaded couplings and exposed threaded areas and inadequate adhesion in plastic or composite piping;
- Wear due to transmission of abrasive fluids;
- Seal failures due to vibration, water hammer effect, ground movement;
- Thermal changes stressing joints, seals and fittings, including freeze damage;
- Improper thrust restraints and pipe supports;
- Damage caused by excavation in pipe area and rock damage when initially laying pipe permitting spot corrosion invasion.
It is easy to replace the bad section of pipe, providing there are no time restraints. Unfortunately, that is not very realistic. Time and production schedules are critical in an on-going operation. Unscheduled shut downs virtually destroy financial projections as a single event can cost millions of dollars in lost production.
First, the pipe flow has to be stopped, the line drained completely and if the fluid is volatile or poisonous, the entire area must be made safe for human exposure and hot work. That involves gas freeing teams and equipment for liquid and vapor recovery to work until the area is brought to safe fire and toxicity limits. Clearing the air in the area alone is time consuming. Add to that the man hours used cutting out the bad section of pipe, locating and reinstalling a new piece, then testing, and the total time can easily amount to the better part of a day and often times more. Man hours, the cost of repair materials and the value of lost production can cost millions of dollars.
First priority is safety of personnel and facility and every reasonable effort must be made to ensure safety. One of the first tests of liability in an injury case is, "Did the supervisor take every reasonable step to assure safety of personnel in such an event?" Management and safety supervisors must be in position to prove they did indeed. We have all heard about the astronomical jury awards when a company has been proven negligent. Driven by contingent fee pots of gold, plaintiffs attorneys will stop at nothing to find a hole in managements' safety program.
Gratefully today, most operations involving hazardous materials have a well established safety program in place with provision for continuing safety education training. These programs include in-house first aid/medical response teams to bring the injured quickly to safety for treatment and/or hospitalization as required, and hazardous materials response teams to secure the leak area and protect others from exposure and/or injury.
Beyond the primary safety considerations, attention turns to the cost of lost production time and alternatives in repair methods that can place the line back on stream in the least amount of time. Most are not serious, but time consuming and costly to repair.
Today, there are viable alternatives enabling in-field repair and restoration of production in much less time than "total replacement." Traditional tools include a variety of clamps and they are fine, if you happen to have the right type and size handy Any given pipeline system will include a great variety of pipe diameters, which means a large inventory of clamps, representing a significant capital investment. These must be on hand and readily available to quickly respond to the problem.
Most of the multi-bolt, flanged, split sleeve clamps, lack conformability due to out-of-round pipe created via excess torque and stress placed on the line resulting from temperature cycling, ground movement and alteration resulting from expansion of piping systems. They are also very heavy and can easily crush mature or thin wall pipe.
Two part epoxy systems for spot patching of minor holes can be effective, but surface preparation and resin mix ratios are critical. The same applies to hand lay-up fiberglass systems, and the resins are usually toxic and highly flammable. Both systems are labor intensive, take a long time to cure and have limited chemical resistance.
Another method is a knitted fiberglass tape, coated with a polyurethane resin formula using simple water to activate, that can be wrapped around the pipe at the leak site. It can be applied by one person in the field and surface preparation is minimal. The tape works not just with carbon steel pipes, but stainless, aluminum, copper, PVC, CPVC, polyethylene, PVDF and most other pipe compositions as well. In about thirty minutes, the resin coated tape becomes a solid, fiberglass reinforced, plastic mass that is highly durable. Training is minimal. The products are non-toxic and can even be used on potable water lines.
Repairs utilizing these tapes are often considered permanent, some having been in place for many years. In other cases the goal is to postpone installing new section of pipe to a more convenient time.
There are quick fix, cost effective products available todaynew solutions to old problems. Proper safety management includes plans for the unexpected. Providing the tools to deal with these events reflect management's concern for its personnel and the environment. These new products can be very useful weapons in management's arsenal to combat problem leaks.
