Like any other mechanical device, valves eventually need to be repaired or replaced. The frequency of these operations depends on the severity of the operating conditions, the design of the valve and the preventive maintenance that has been performed. In a few documented cases, valves originally installed at the turn of the century are still operating fine. In other cases, where the environment is severe, valves have lasted only a couple of weeks before they needed to be repaired.
Although complete replacement sounds like the easiest solution, it might not be the best choice. First, the cost will be high. Second, if it is not a commodity-type valve, manufacturer delivery might require a long wait.
In addition to a few OEMs that repair their own products, quality independent valve repair companies exist in most parts of the United States. Although many companies say they repair valves, the complexity of some of today's quarter-turn products requires you to be sure you are dealing with a company that is qualified to handle the job.
The Valve Manufacturers Association of America (VMA) created The Valve Repair Council (VRC) 12 years ago to provide a network of OEM-authorized and audited valve repair facilities. The 30 members of VRC are the cream of the crop when it comes to valve repair. So when you are looking for a valve repair facility, look for VRC authorization.
What does it cost to repair a valve? Because of the differences in valve types, no one "average" can be calculated. However, a good rule of thumb is that the repair will cost anywhere between 40 percent and 60 percent of the cost of a new valve.
When specifying new valves, you might want to consider the repairability of a particular type or brand. Often, that temptingly cheap valve can be difficult or impossible to repair as the result of design flaws or the high cost and/or lack of availability of parts. Therefore, you should look at the total cost of ownership, not just the original purchase price.
Getting tech assistance
Most valve manufacturers and distributors are usually happy to offer valve application or operation assistance. However, the salesman might not have the engineering background to answer specific technical questions.
Because of liability concerns, some manufacturers are even hesitant to go out too far on that informational limb. It is also very unlikely that a manufacturer will give you much information about a competitor's product. If you have several different brands from several different distributors, your information search could turn into more of a scavenger hunt.
Additional survival help can be found in the publications of the various standards-making organizations. Virtually all valves are built to both material specifications and one or more industry codes or standards. Standards and specifications cover virtually every type of valve, from plastic industrial ball valves to instrument valves. Although the primary purpose of these documents is to produce standardized products, they also contain a wealth of general information. These documents and the organizations that publish them are a good starting point.
For control valves, the primary organization is The Instrumentation, Systems, and Automation Society (ISA). ISA has published a number of standards that deal with control valves, covering topics from end-to-end dimensions to testing requirements. The organization also offers control valve training courses at various sites around the country.
The oldest valve standards-making organization in the United States is MSS. Its first standard was published in 1924, and the organization estimates it has distributed more than 50,000 standards documents during its 78-year history. The MSS inventory currently includes 72 valve-related standards.
The American Petroleum Institute (API) also publishes several valve standards. Gate valves, ball valves, corrosion-resistant gate valves and valve inspection and testing are some of the topics covered by the institute's standards.
The American Society of Mechanical Engineers (ASME) has a long history of standards creation and stewardship. The most important ASME valve document is B16.34, Valves ," Flanged, Threaded and Welding End.
The heart of this document is the 60-page pressure-temperature ratings section. Tables cover virtually all of the common valve materials in use today, including stainless steels and nickel alloys. B16.34 also contains design information and nondestructive inspection procedures.
The American Society for Testing and Materials (ASTM) does not publish valve standards, but does produce the material specifications used for the manufacture of the valve components.
Historically, valve standards have been dominated by the above-mentioned standards-making bodies; however, the landscape is changing. Increasing international participation, combined with decreasing U.S. participation, has opened the door to International Standards Organization (ISO) valve standards acceptance worldwide. In some cases, U.S. standards have been adopted verbatim, but the current trend is toward new documents created from scratch by European-dominated committees.
Armed with a good attitude and the right survival gear, you can brave the "valve jungle." Do not be afraid to ask for help, and remember that it is your responsibility to care about the valves under your control.
Johnson is president of United Valve, South Houston, Texas. Contact him at firstname.lastname@example.org.
Much like squirrels storing acorns for the winter, most engineers seem to store information such as books, reports and pamphlets for possible later reference. When it comes to valves, some excellent volumes are available to help keep that bookshelf firmly anchored to the floor. During the past 20 years, eight excellent valve books were published.