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East Coast Refiners Eye Texas as Alternative to North Dakota

Wednesday, 26 April 2017  |  Chris Guy

“Major U.S. East Coast refiners profited from railing hundreds of thousands of barrels of discounted Bakken crude to their plants daily from 201...

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Industry Headlines

Metso Providing Valves for Oman Petrochemical Complex

8 HOURS AGO

Metso will supply 400 Neles emergency shutdown (ESD) valves for an ethylene cracker as part of the new Liwa Plastics Industrial Complex (LPIC) Project in Sohar, Oman. The new complex will process light ends produced in Orpic's Sohar Refinery and its aromatics plant as well as optimize natural gas li...

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Curtiss-Wright Earns Safety Award for Third Year in a Row

9 HOURS AGO

A Curtiss-Wright facility located in Chanhassen, MN, received a Governor’s Safety Award for superior performance in workplace safety and health as part of the Minnesota Governor’s Safety Awards. The Chanhassen site produces Exlar electric actuators and earned this award by reporting better...

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East Coast Refiners Eye Texas as Alternative to North Dakota

4 HOURS AGO

“Major U.S. East Coast refiners profited from railing hundreds of thousands of barrels of discounted Bakken crude to their plants daily from 2013 until 2015. But as more and more pipelines were built in North Dakota, the discount began to disappear, and so did the rail cars,” Reuters repor...

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Wind Energy Growing Nine Times Faster Than Overall Economy

1 DAY AGO

American wind power added jobs over 9 times faster than the overall economy amid robust growth for another year, according to the American Wind Energy Association (AWEA), which just released its annual report. Installing over 8,000 MW of new wind power for a second straight year, the U.S. industry inv...

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Texas Manufacturing Expansion Continued in April

1 DAY AGO

Texas factory activity increased for the 10th consecutive month in April, according to business executives responding to the Texas Manufacturing Outlook Survey . The production index, a key measure of state manufacturing conditions, moved down three points to 15.4, suggesting output growth continued b...

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Are Women the Key to Closing U.S. Skills Gap?

2 DAYS AGO

The Manufacturing Institute, Deloitte and APICS have just released, “Women in Manufacturing: Stepping up to make an impact that matters.” The joint study is the result of more than 600 survey responses from women professionals in the manufacturing industry, along with nearly 20 manufactu...

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Addressing Welding Procedures Not Covered by ASME Section IX

materials_q_and_a_graphicQ: My customer has rejected my welding procedure specification (WPS) and has asked me to address items that are not required by ASME Section IX. Is this reasonable?

A: Yes, this is a reasonable request. In many cases, it is a good idea to address items not covered by Section IX1.

Many people view any given ASME code section as a handbook, and assume that if they follow everything in that code section, they have met all necessary requirements. However, each ASME code section has verbiage in the foreword warning the user that merely following the rules in that particular section will not ensure an adequate design. Such wording is phrased in ways like: “The user of the Code should refer to other pertinent codes, standards, laws, regulations or other relevant documents,” and “it is not intended that this Section be used as a design handbook; rather, engineering judgment must be employed in the selection of those sets of Code rules suitable to any specific service or need.”

For example, Section IX does not impose enough controls to ensure reliable weld joints because it does not address the proper choice of filler materials. Section IX would allow welding nickel alloys or copper alloys together using carbon steel filler, provided the qualification specimen passed the appropriate mechanical tests. Many variables are not required to be addressed in a Section IX WPS. But in many of these cases, a WPS that does not address those variables may not produce consistently reliable weld joints or provide adequate guidance to the welder, both of which should be the primary purpose of the WPS.

The following are examples of factors Section IX does not require, but that should be considered for inclusion in a WPS:

1. There are supplementary essential variables not required to be addressed for a WPS to be used on materials that are not impact-tested. One such essential variable is heat input, which is calculated based on current, voltage and travel speed. If heat input does not need to be addressed, Section IX does not require including voltage or travel speed values. Some of the software packages for creating WPS documents will even omit this information automatically. On the other hand, if no voltage or travel speed values are specified, it is possible to follow the WPS and still produce unacceptable welds. Therefore, even though not required by Section IX, it is beneficial to include reasonable voltage and travel speed values on the WPS—even for materials that are not impact-tested.

2. For a WPS that involves carbon and alloy steels postweld heat-treated (PWHT) below the lower transformation temperature (LTT), Section IX only requires the WPS to indicate the PWHT must be below the LTT.

Most WPSs for non-impact-tested carbon steels and alloy steels will actually state a PWHT temperature, but many omit the tolerance on this temperature and any soak time requirements.

To ensure that proper strength, ductility and hardness requirements are met, a PWHT temperature range should be stated on the WPS. That temperature range should be based upon the PWHT temperature used on the qualification coupon, taking into consideration the effects of higher and lower temperature on the strength, ductility, hardness and toughness of the material. In addition, as a function of base metal thickness, guidance should be provided regarding the soak time, as well as providing absolute minimum and maximum allowable soak times. Again, strength, ductility, hardness and toughness of the material should be taken into account.

3. Section IX does not prohibit combining procedures that have been qualified in different ways, such as procedures qualified with and without PWHT, or procedures qualified with and without controls required for impact-tested materials. In fact, creating one WPS that covers non-impact-tested material (such as WCC) and impact-tested material (such as LCC), with and without PWHT is both possible and allowed. These procedures are handy when it is necessary to get a customer review. However, the combined procedures tend to be difficult for welders to follow because they usually contain a number of notes and tables, and for any given job it can be hard to determine what information actually applies.

Although the combined approach is allowed, and although the combined document might be convenient from a creation and maintenance standpoint, it is actually better to create four separate WPS documents (non-impact without PWHT, non-impact with PWHT, impact without PWHT and impact with PWHT), because each WPS will then convey much more clearly the specific requirements for the pertinent situation.

In summary, although Section IX imposes an abundance of rules for qualifying and writing WPSs, there are many instances where additional controls and information need to be conveyed to ensure results that meet the intended requirements of the weld. Therefore, if your customer makes a comment on your welding procedure, view it as a possible learning experience. In the end, your WPSs will be better for it.

Reference:

ASME Boiler and Pressure Vessel Code, Section IX, “Qualification Standard for Welding and Brazing Procedures, Welders, Brazers, and Welding and Brazing Operators,” American Society of Mechanical Engineers, New York, NY, USA.


Don Bush is a principal materials engineer at Emerson Process Management-Fisher Valve Division (www.emersonprocess.com). Reach him at This email address is being protected from spambots. You need JavaScript enabled to view it..

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