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Valves in a Cement Slurry Line

Valves in a Cement Slurry Line

Basically everywhere you look in modern ...

Triple Offset Butterfly Valves

Triple Offset Butterfly Valves

Since their introduction to the market m...

Digital Valve Control Leads to Increased Plant Availability

Digital Valve Control Leads to Increased Plant Availability

Surge is characterized by fast flow reve...

Cast vs. Forged: The Ongoing Debate Takes a New Direction

Cast vs. Forged: The Ongoing Debate Takes a New Direction

In the valve industry, the cast versus f...

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Industry Headlines

Industry Headlines

VMA Members Among Plant Engineering 2016 Product of the Year Finalists

3 DAYS AGO

Several VMA members are among this year’s Plant Engineering Product of the Year finalists. Emerson has products nominated in four different categories, while Siemens has several products nominated in a total of three different categories. Chesterton and Hunt Valve have products up for awards the...

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MSS Publishes Revised American National Standard for Steel Pipeline Flanges and Receives ANSI Approval

4 DAYS AGO

The Manufacturers Standardization Society (MSS) announces that the substantially revised Standard Practice, SP-44-2016, Steel Pipeline Flanges, has been approved by the American National Standards Institute (ANSI) as a Revised American National Standard (ANS).

The first edition of MSS SP-44 was publish...

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U.S. Chemical Industry Remains Optimistic for 2017

3 DAYS AGO

Moving into 2017, the U.S. Chemical Processing Industry continues to enjoy optimism about future investment, according to Industrial Info's 2017 Global Industrial Outlook . Much of this activity stems from the continued low cost of natural gas liquids (NGLs), a primary feedstock for building-block che...

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Hydraulic Institute Celebrates Centennial with New Logo

4 DAYS AGO
Hydraulic Institute Celebrates Centennial with New Logo

The Hydraulic Institute (HI) will celebrate its centennial in 2017 with a new logo as part of a larger initiative to position HI for the next 100 years of service to the pump industry. The new logo is a key element of HI’s overall brand refresh and redesign process.

The logo includes a hidden &ld...

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U.S. Adds 178,000 Jobs, Unemployment Rate at 4.6%

2 DAYS AGO

The unemployment rate declined 0.3% to 4.6% in November, and total nonfarm payroll employment increased by 178,000, the Department of Labor reported today. Employment gains occurred in professional and business services and in health care.

Employment in construction continued on its recent upward trend...

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Third Quarter GDP Revised Up to 3.2% Growth

4 DAYS AGO

Gross domestic product (GDP) in the U.S. increased at an annual rate of 3.2% in the third quarter of 2016, according to the second estimate released by the Department of Commerce. In the second quarter, real GDP increased 1.4%.

This new GDP estimate is based on more complete source data than were avail...

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A Guide to Valve Cleaning and Specifications

Most of the time we only require that valves be free of basic dirt and debris before they are put in service. However, occasionally service requirements dictate that all traces of oil, dust and grease be removed. A prime example is valves to be used with oxygen. In that case, even a small speck of oil in a 100% oxygen environment can create a devastating explosion. One tiny metallic sliver could cause a minute spark, which is all that would be required to trigger the destruction.

 

Other media that require this level of cleanliness include numerous other pure gases, chlorine, paints and some chemicals. What all this means is that a standard, off-the-shelf valve cannot be used in these media unless it has been properly processed before installation. Decades ago, achieving this degree of cleanliness required the use of vapor degreasing machinery filled with a chlorinated solvent such as trichloroethane. These chemicals worked marvelously to clean, but they have been proved to be carcinogens, so their industrial cleaning usage has all but disappeared. In their place, environmentally friendly aqueous-based cleaners, such as Simple Green, have become the norm.


Follow the Specs

Even with the use of the right cleaning agent, however, it takes more than a simple “wash behind the ears” to ensure that a valve is clean enough for intended service. This is where cleaning standards and specifications come in. Fortunately, there are very good specifications to guide valve assemblers and technicians in the cleaning process. In fact, the American Society for Testing and Materials (ASTM) has a committee that works solely on specifications for oxygen service applications: Committee G04. This group produces ASTM G93, “Standard Practice for Material and Equipment Used in Oxygen-Enriched Environments,” which is a very thorough document and an excellent reference for valve cleaning procedures.

The Compressed Gas Association (CGA) publishes another often referenced cleaning standard: document CGA G-4.1, “Cleaning Equipment for Oxygen Service.” Many end-users that don’t have their own specific procedure reference the CGA 4.1 standard. The Manufacturers Standardization Society (MSS) also recently created a valve cleaning standard, MSS SP-138-2009, “Quality Standard for Oxygen Cleaning of Valves & Fittings.” This document is derived from many end-user specifications as well as CGA G-4.1. For chlorine service cleaning, the Chlorine Institute references cleaning procedures in its document: “Piping Systems for Dry Chlorine.”

The common denominator for all the cleaning standards is removal of all traces of oils, grease, dirt and other contaminants. The methods prescribed include scrubbing, ultrasonic cleaning, pressure blasting and sand blasting.


Rust Elimination

One important issue in cleaning is the presence of rust on carbon steel components after cleaning. With any of the prescribed cleaning processes, the protective film or rust preventative on the steel is removed, which exposes the metal to rapid oxidation, a problem that is particularly acute in humid environments. In many cases, a light blush of rust is acceptable, but gross deposits would not be. As a result, cleaning may need to be performed in a non-humid area. Additionally, carbon steel valves and components that have been cleaned require some form of corrosion protection—either desiccant bags inserted in the valve bore or an exterior wrapping with vapor phase inhibitor paper, or both.

After valves have been carefully cleaned and checked for proper cleanliness, they are usually put in protective heavy-gauge plastic bags to ensure they stay clean until installation.

Cleaning of valves is a straight-forward process that requires some diligence and quality control. However, guidance is available from various standards and specifications. Also, since the valves must be disassembled for most cleaning procedures, it’s important that the personnel involved be familiar with proper disassembly and re-assembly of the valves to be cleaned.

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Greg Johnson, a contributing editor to Valve Magazine, is president of United Valve (www.unitedvalve.com), which offers factory-authorized valve modifications and repair from its Houston, TX facility. Reach him at This email address is being protected from spambots. You need JavaScript enabled to view it..

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