Leak-detection fluid options

National Grid tests a leak-detection fluid’s properties in the field.

Bubble soap. Leak soap. Soap solution. Bubble fluid. Leak-detection fluid. It’s all the same—simple dish soap and water, right? Wrong! This simple fluid is more complex and has more duties and uses than are typically realized.

One great quality of gas-industry field personnel is that they are not shy about voicing opinions on the products they use in the field, especially regarding poor-performing leak-detection fluid. During application in the field, when a bubble solution fails to bubble on gas leaks, freezes on the pipe or in the container, doesn’t lubricate the gaskets or causes choking and coughing, word gets around.

Mangers know the majority of tests should concentrate on the ability of the leak-detection fluid to bubble in the presence of a leak. During its years of testing products, National Grid, Materials & Testing Laboratory found one solution that bubbled on air leaks, but not on gas. After evaluation, it was revealed that the manufacturer put an additive into the solution to improve the quality of the product. The additive had an adverse affect on the ability of the solution to create bubbles in the presence of gas.

Lesson learned? Managers should conduct tests with many test gases, including helium, nitrogen or other gases as well as with air.

Also, to prevent downtime caused by inappropriate fluid, managers should become familiar with various products and applications by determining each specific fluid’s fitness for use, the application environment and the product’s level of quality.

Consider all applicable materials

Various formulations of leak-detection fluids are produced for specific purposes.

In the gas industry, many materials are buried below the street, including various pipes and fittings. The leak-detection fluid has to bubble on such materials as steel, cast iron, ductile iron, copper, PVC, stainless steel, MDPE, HDPE, nylon, rubber and other types. Managers tasked with testing leak-detection fluid should determine if there is an adverse reaction with any of these materials.

For example, polyethylene pipe appears to be the most susceptible to slow crack growth when it comes into contact with some of the ingredients or surfactants used in bubble solutions. When conducting long-term, sustained-pressure tests, leak-detection fluid is substituted for water as the test medium. Some bubble solutions were found to cause polyethylene pipes to develop cracks and leaks.

Also, managers should not be fooled by all-natural ingredients. During testing, National Grid found that the composition of all-natural ingredients in one brand was one of the selling points of the worst leak-detection fluid it tested. The polyethylene pipe cracked within a few hours of sustained-pressure testing. Another surfactant was found to severely corrode copper, brass and bronze.

Meanwhile, threaded pipe usually has cutting oil and pipe-thread sealants on it. Both of these materials can affect the bubbling capabilities of the leak-detection fluids. Particularly damaging to these capabilities are Teflon-containing pipe-thread sealants. They can contain a type of oil that helps suspend the Teflon particles. Product tests show such sealants can affect the bubble solutions in varying degrees, from no bubbles to a few bubbles, unless the leak-detection fluid has been formulated to work with those pipe-thread sealants. To date, National Grid has found only two such specially formulated leak-detection fluids.

Bubble fluid must also work on various surfaces where bar holes were made to check for gas leakage over a gas main or service. That is, it must be able to be drawn over a bar hole drilled in asphalt or concrete to indicate a gas push over that spot. The area may also have soil around it and high concentrations of salt after a snow. The leak detection fluid must be tested to be sure that it can perform properly in this environment.

Hot and cold leaks

Leak-detection fluid should bubble when gas is pushed through sand or dirt.

Seasonal-temperature variance can affect leak-detection fluid performance. Care must be taken to ensure fluid does not evaporate immediately in the heat of the summer. Conversely, managers don’t want it to freeze on the leak and seal it, nor freeze in the container during wintertime.

Some companies choose to stock a summer and a winter formula. Yet, it is important to note that the two types of fluids must be separately stocked. Managers can withdraw their choice according to outside temperature, but, with storage space at a premium, some companies choose to order summer and winter solutions during each season and stock them under one code. If too much summer fluid is ordered, and cold sets in, workers will have frozen leak-detection fluid.

In some cases, this situation can encourage workers to become inventive and add automobile antifreeze to the mixture. Some of the additives in car antifreeze can react with the bubble solution and reduce the bubbling capabilities. The mere action of diluting the solution with antifreeze will also reduce the bubbling capabilities.

The other choice is to restrict orders to a winter fluid that can work equally as well in the summer. In this way, managers only stock one fluid in the same warehouse and save storage space. For the field personnel, the usage becomes seamless. Other characteristics of which to be aware when choosing fluid include the tendency for false results, human and environmental impacts, adequate lubricity, bubble sustainability and anti-static properties.

False positive. Some additives may actually produce false-positive gas-leak readings. This is especially true with solutions that contain alcohol as a solvent or antifreeze. In addition, too much alcohol in leak-detection fluid makes a flammable mixture. Before using a new solution, personnel should take a gas reading when opening the container.

Choking, coughing. During some fluid field-use, National Grid received a rash of physical complaints from users. People who used the solution reported a choking feeling in their throats and began to cough. The culprit chemical in this case was triethylamine. It bubbles well and is comparatively less expensive that other ingredients. National Grid now specifies that no triethylamine or other toxic chemical can be used to produce leak-detection fluid. Managers should check material data safety sheets that are provided with orders of fluid to be sure harmful chemicals are not part of the mix. Managers can also specify that no unapproved changes be made to formulation without proper notice.

Environmental issues. There are various types of antifreezes that can be added to leak-detection fluid to keep it from freezing. However, they are not all environmentally friendly. Some are banned by local water districts or are allowed to be used only in small quantities. Managers should check with local DEP regulators for restrictions.

For example, ethylene glycol cannot be broken down by the liver and can do serious damage to the body if ingested by humans or animals. Restrictions are in place to avoid having the chemical reach municipal water reservoirs because it doesn’t break down naturally and can pollute the water system.

Propylene glycol can be broken down by the liver in humans and animals. However, in high concentrations, it too can permeate down to the water system unchanged. This product is also banned by some local water-district regulators. Today, there are some new environmentally friendly antifreezes that are safe for humans and animals. These antifreezes are made of complex carbohydrates. They are now being used in leak-detection fluids with excellent results. The new fluids don’t interfere with the bubbling capabilities of bubble solutions and they lower the temperature of the leak-detection fluids as they should. They also add a lubricity to the soap solution.

Lubricity. Why is lubricity important? In the gas business, many fittings with gaskets are used. The manufacturer’s instructions will instruct users to put a soap solution on the pipe and gaskets so the gaskets will slide into position when the fitting is installed on the pipe. They also instruct the installer to add antifreeze in the winter to keep the solution from freezing. The larger fittings require more solution to achieve the required lubricity results. Some leak-detection fluids have the lubricity of plain water. They offer no help in installing these fittings.

Good fusion. When a project requires the fusing of a fitting onto a polyethylene pipe or the need to coat a bare steel pipe, workers should remove the leak-detection solution off the pipes. No residue of the leak-detection fluid should be left on the pipe. This residue can be detrimental to achieving a good plastic fusion or a successful adhesion of coating material on a steel pipe. When choosing a product, managers should ensure the leak-detection fluid can be washed off with plain water.

Anti-static properties. To date, all the leak-detection fluids National Grid has tested also work as antistatic fluids. The differences are in the way they wet the surface. Some puddle in spots on polyethylene pipes, while others spread evenly across the surface. They all appear to wick cloth or rags, but an even coating across the surface without a cloth is preferred. This gives a continuous electrical path back to ground when the solution is sprayed to the edge of the trench.

Over all, it is clear that this simple product is not as simple as it seems. Leak-detection fluid is the most important tool to use to detect a minute leak and has many other uses for gas systems. National Grid advises clients to be sure to know what is expected from a particular fluid and to always test and try it before sending it out to the field.