ASME F-Numbers
F-NUMBER GROUPINGS PER ASME SECTION IX
WHAT IS AN F-NUMBER
An F-Number is a numeric designation assigned to a group of filler metals. ASME Section IX Table QW-432 lists the assignment of filler metals into their F-Number grouping.
The grouping of filler metals is based on qualitatively defined usability characteristics, which fundamentally determine the ability of welders to make satisfactory welds with a given filler metal. This grouping is made to reduce the number of welding procedures and performance qualifications, where this can logically be done.
With a fundamental understanding this system can be very useful in simplifying the determination of who is qualified to perform joining work within the ASME codes.
F-NUMBER and P-NUMBER and A-NUMBER
F-Number : Filler Metal
P-Number : Base Metal
A-Number : Weld metal in the “as-welded” state
FILLER METAL ALLOY GROUPINGS
F-Numbers have been laid out as chronological numeric segments which are assigned to different alloy groups as detailed in the following table.
ASME F-Number Material Type Groupings
F-NUMBER LIST
The following is a comprehensive list of F-Numbers, their general alloy grouping description, the associated SFA Specification, and the description of the specification.
ASME F-Number Listing
F-NUMBER RANGE FOR WELD PROCEDURES (WPS)
When a welding procedure is qualified, a PQR or Procedure Qualification Record is created. A PQR creates a record of the original set of qualification variables by documenting the actual values of the original essential variables. For many of the variables on a WPS, there are permitted ranges that the author can specify based on the actual values of the PQR.
In the case of F-Numbers, no expanded range is permitted based on the PQR actual values, but instead the F-Number must be the same value as was used on the PQR. For reference see ASME Section IX Tables QW-252 thru QW-267 and paragraph QW-404.4.
Other essential variables related to filler metal such as classifications do permit some latitude based on rules set forth in ASME Section IX, all of this reinforces the importance of being familiar with the code book requirements for each variable.
F-NUMBER RANGE FOR WELDER QUALIFICATION (WPQ)
When welders take a qualification test, the filler metal used during the test is recorded as an “Actual Value”. The filler metals specification, classification, and F-Number are recorded in the Actual Values column, but only the F-Number is recorded in the “Range Qualified” column.
ASME F-Number Ranges for Welder Qualification
FILLER METAL LISTED IN QW-404 ON ASME WPS
The following is the filler metal section from the ASME welding procedure (WPS) detailing how the Specification, Classification, F-Number, A-Number, and UNS Number are associated.
ASME WPS Filler Metal Section