AWS CWI - Book of Specification - Minimum Preheat & Interpass Temperature

[shipyard87]

Hi All experts,

Could you help me with my query pertaining to the finding of minimum preheat & interpass temperature of dissimilar base metal welded together.

By using Appendix XV of Part B - Book of Specifications, under footnote number (d), it states that "In joints involving combinations of base metals, preheat shall be as specified for the higher strength steel being welded."


For Example the two dissimilar base metal are:
ASTM A573 Grade 65 (SMYS=240 MPa; SMTS=450MPa)
ASTM A607 Grade 45 (SMYS=310 MPa; SMTS=410MPa)


From the data in Appendix XIV of Part B - Book of Specifications, should I compare the value of Yield strength (SMYS) or Tensile strength (SMTS) in order to determine the higher strength steel. Then to use the identified higher strength base metal to determine the correct minimum preheat & interpass temperature data for a given thickness from Appendix XV.


Thank you

 

[SectionIX]

Tensile Strength, because filler metals and materials are selected by this property for AWS Code issues.

In the case above, all things being equal for any given thickness, ASTM A573 Grade 65 has a higher preheat than ASTM A607 Grade 45

As a side note, even though API 1104 classifies materials by yield strength, filler metals are chosen to match the parent material tensile strength.

 

[racookpe1978]

Careful!
The AWS "Part B" Specifications Book is only for the Practical Factors (Part B) of the three-part AWS CWI exams.

It follows, and IS similar to actual specifications manuals, but it is NOT a working welding specification manual. Please, re-check what reference you are reading.

 

[gtaw]

If you are studying for the CWI examination, be forewarned the Part B examination is totally new examination (as of January 2016). The Book of Specifications is new, the weld samples are new and very different from the old ones, and there is a new book of exhibits containing WPS, PQRs, and WQTRs that must be used to answer 46 questions.

The new part B examination; well, let's just say I would not want to take it without some time in the classroom to review the new materials.

Best regards - Al