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Last updateMon, 26 Sep 2016 7pm

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Industry Headlines

Alaska, ConocoPhillips Forming LNG Joint Venture

Monday, 26 September 2016  |  Chris Guy

The State of Alaska, through the Alaska Gasline Development Corporation (AGDC), and ConocoPhillips Alaska Inc. have executed a Memorandum of Understan...

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Industry Headlines

Flowserve's Mark Blinn Announces Retirement

13 HOURS AGO

Mark Blinn plans to retire as Flowserve president, CEO and a member of the board of directors. To ensure an orderly transition, Mr. Blinn will remain in those roles until the appointment of his successor.

Flowserve’s board of directors has a robust succession planning process and, in an effort to...

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Powell Valves Names Niagara Controls as Exclusive Representative

16 HOURS AGO

The Wm. Powell Company (Powell Valves) and Niagara Controls LLC., a division of The Collins Companies, have entered into an exclusive agreement to represent and distribute Powell Valves to Praxair.

Based in Buffalo, NY, Niagara Controls is a technical sales representative and stocking distributor for m...

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Alaska, ConocoPhillips Forming LNG Joint Venture

11 HOURS AGO

The State of Alaska, through the Alaska Gasline Development Corporation (AGDC), and ConocoPhillips Alaska Inc. have executed a Memorandum of Understanding regarding negotiations to form a joint venture (JV) that could facilitate marketing LNG from the Alaska LNG project to global LNG markets and acqui...

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Many Houston Chemical Facilities Could Be Operating Illegally

12 HOURS AGO

“Firefighters once routinely visited buildings in their districts to plan for emergencies — including ferreting out hazmat sites — but those visits stopped in April 2014. The department had started entering old plans into a new, sophisticated database and didn't want to create a ba...

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Manufacturing Growth Eases Again in September

3 DAYS AGO

At 51.4 in September, the seasonally adjusted Markit Flash U.S. Manufacturing Purchasing Managers’ Index (PMI) was down from 52.0 in August and pointed to the weakest improvement in overall business conditions since June. The latest PMI reading marked seven years of continuous growth across the ...

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Leading Economic Indicators Down Slightly in August

4 DAYS AGO

The Conference Board Leading Economic Index (LEI) for the U.S. declined 0.2% in August to 124.1, following a 0.5% increase in July, and a 0.2% increase in June.

“While the U.S. LEI declined in August, its trend still points to moderate economic growth in the months ahead,” said Ataman Ozy...

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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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