Valve Magazine - Fall 2011

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 com-
bining procedures that have been
qualified in different ways, such as
procedures qualified with and with-
out 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 pro-
cedures tend to be difficult for
welders to follow because they usu-
ally contain a number of notes and
tables, and for any given job it can
be hard to determine what informa-
tion actually applies.

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. VM

Reference:

1ASME 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 Don.Bush@Emerson.com.

SPEC IT AND FORGET IT.

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