Leak-proof gaskets provide major savings

Blowouts and chronic gasket failures continue to plague utilities and industrial power plants. Such failures give rise to a litany of related problems, including loss of productivity and leakage.

In the face of spiralling fuel costs as well as safety, regulatory and green issues, the power industry naturally looks to new technologies and systems integration for solutions.

While utilities and industrial powerhouse engineers and maintenance supervisors focus on major power generation systems, they may overlook sub-assemblies, where improved technologies and products can have a substantial impact on operations.

Once such subassembly is gaskets, where failures can have expensive and even hazardous consequences.

In fact, the 'science' of gasket sealing is a popular subject of trade association conferences.

Yet blowouts and chronic gasket failures continue to plague utilities and industrial power plants.

Such failures give rise to a litany of related problems, ranging from loss of productivity, untimely shutdowns and dangerous leakage problems, to tedious, repetitive gasket replacement and costly inventory of a wide variety of replacement gaskets.

"For a power utility or industrial power plant to be able to install a flange gasket and not worry about blowouts and leakage would represent a major savings of time and money", says Wayne Boyd, a field specialist with AW Chesterton Co, Rome, Georgia.

"However, using gasket systems of the latest mechanical design, it is possible to achieve very substantial savings on maintenance and also reduce gasket inventory investments".

Because gasket applications involve many complex factors - application conditions, friction, materials, mechanical design, fluid mechanics, heat transfer and so on - one might suppose that a huge range of gasket materials and configurations are necessary.

However, technological advances made in the development of fighter aircraft for the US Air Force have led to the design of a leak-proof mechanical gasket system that can be used with a wide thermal cycle and control range.

Using this technology to develop a leak- and blowout-proof gasket 'system', the Selco Seal produced by Sealing Corp (North Hollywood, California) offers inherent advantages over the traditional spiral-wound type of gasket for critical power plant applications.

These include heat exchangers, steam crossovers, manways, soot blowers and many types of flanges, applications found in many utilities and industrial power systems.

"Up to 70% of gasket cost is in installation", says Mel Lowry, Sealing Corp's Vice President and General Manager.

"By using gaskets that create leak-proof flanges and will last for years, users will enjoy very substantial gains on maintenance cost as well as productivity while eliminating potentially hazardous emissions".

"Plus, the 'one-size fits all' design also means sizable savings on gasket inventory costs".

In some applications, maintaining proper gasket seal is a serious and chronic problem.

In boilers used by the power industry, for example, problems with manway gasket are very common.

Because boilers are constantly cycling, the conventional spiral wound type of manway gasket has very little bolt recovery and is therefore prone to leakage and blowouts.

Lowry says that his firm's unique gasket design requires minimum seating stress on bolts (under 3000 psi), resulting in high recovery and a very reliable seal in boiler applications.

OEM suppliers can realise substantial manufacturing savings and added sales by purchasing components or sub-assemblies based on orders for their own products.

"For our operation that means very quick turnaround with a well-engineered product that can be used reliable in applications with working pressures up to 6000psi", said Robert Davenport, Vice President of Cornerstone Valve USA (Houston, Texas).

Cornerstone Valve produces specialty ball, swing check, choke and rotary control valves covering a broad range of application areas including the power, oil and gas, and petrochemical sectors as well as various NASA- and Navy-related services.

"We use Selco seals in our bonnet-to-valve body seals because we can get very fast turnaround on orders", said Davenport.

"Plus, the seal design provides multiple sealing along potential leak paths, so it is very efficient and very reliable".

Heat exchangers used in power system applications provide many challenges that highlight the benefits of this advanced gasket design.

With flanges having two opposing temperature zones, because of the hot and cold sides of the heat exchanger, there are differing loads on both sides the gasket.

This resulting stresses translate into a 'live load' requirement that results in frequent service, including gasket changes that are cumbersome and time-consuming.

However, when used in conjunction with a proper live loading program, the Selco Steel Trap gasket will hold as strongly as a weld for three years.

"These gaskets have proven to be a successful solution to preventing leaks in several heat exchangers", said George Pyros, an engineer with power systems giant Siemens Westinghouse.

"These gaskets prevent leakage whether of the gas or the water from the heat exchangers, which are typically used on combined cycle power plants".

Joint leakage and blowouts can result from bolt elongation as well as gasket failure.

Fabsco Shell and Tube Llc (Tulsa, Oklahoma) also manufactures heat exchangers, including those that are commonly used for gas heaters in the power industry.

"These are very cyclic operations", says Fabsco Chief Engineer Ron Shipman.

"In any type of high-pressure application we use the Selco gasket rather than standard solid iron gaskets".

"They don't require as much torque, and if a joint loosens due to bolt elongation, the gasket is still going to maintain a good seal".

"In the overall, we have had the greatest success with the Selco product".

Chesterton's Wayne Boyd says his firm supplies gaskets to Georgia Power, a Southern Company, which has specified Selco as Best Practice.

"They go into the turbines, where they any leakage creates a problem because those units operate under vacuum", explained Boyd.

"If they have a substantial air leak, they have to shut down, which results in a big cost hit for them".

"For the customer to be able to put a gasket in and not worry about it leaking means a big saving of time and money".

"Now instead of changing gaskets every few weeks, they only have to change them every few years".

The Selco Seal has demonstrated five-plus years of leak-free operation.

Boyd adds that industrial users enjoy added savings by using the Selco gasket design not only in their power plants, but in other applications as well.

"Often, one gasket design will cover a range of applications, simplifying maintenance while reducing inventory investment requirements".

"We were able to cut the cost of gaskets in half at the Temple-Inland paper mill in here in Rome", said Boyd.

"The local mill has standardised on the Selco Steel Trap gaskets throughout the plant, replacing a whole slew of other gaskets".

"The self-locator Selco gasket fits flanges throughout the mill, including those in the power plant, recovery bores, power bores, steam lines going to the paper-making machines as well as pumping water".

"This standardisation has simplified maintenance and reduced inventory costs with a single, reliable gasket that's easy to install".

When power system applications require custom gasket designs, lead times can be critical.

This is especially important when gasket failures lead to shutdowns, which often result in lost productivity, angry customers and very expensive replacement costs".

"One of the important advantages in specifying Selco gaskets is the lead times are generally very short", said Greg Gravenmier, Product Specialists for Sealing Specialists of Missouri".

"Selco also does custom shapes, sizes and designs".

"So, for equipment that is old and worn, they can retrofit the gasket to seal in portions of the flange face that are not damaged".

"Also, while deliveries for special orders often require extended manufacturing time, we usually have a very quick turnaround from Selco".

Major utilities including Duke Power, Ontario Hydro Energy, Con Edison, Baltimore Gas and Electric (BGE), Florida Power and Light (FPL), Hoosier Energy and many others are also using the Selco product line.

Many of these utilities have plants that are on track to achieve at least five years of leak-free, trouble-free, no-maintenance operation of steam generator flanges and Selco manway gaskets.

Operating conditions of 1000F and 1900psi are common for these applications.

Extending the time between maintenance cycles from approximately two to five years not only increases the profitability but also eliminates the cost of downtime and repair.

The Selco seal is a non-asbestos metal gasket, designated The Hybrid by the US Navy, which uses this seal extensively as the replacement for spiral wound on all lube oil and fuel oil service on fleet ships.

This gasket consists of both a metal carrier and a sealing material.

It maintains a less than T-3 seal under large changes in temperature and pressure.

This product is easy to install and does not require re-torquing.

A self-locating design is available to fit multiple classes certain pipe diameters, which helps to reduce gasket inventories.

Selco gaskets exceed current and projected EPA Fugitive Emission Requirements, and are certified to conform to various size standards.

Gaskets can also be fabricated to your exact specifications or drawings.

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