Arggg A numbers, M numbers, F numbers, L,M, N, o, P numbers

By jimstucker Date 08-25-2019 23:09

Anyone have a good source for learning about how these "AWS D1.1" numbers work?
I call them D1.1 numbers because some of them are mentioned in that code book, and I'll be taking the D1.1 CWI seminar and exam soon, and these classification and group numbers have me baffled.
I have yet to find a good source that explains what these are about. However, it appears from the practice tests that these numbers are really important.
Please help by posting a good link, or the name of a book, that can tell me how to use these numbers.
thanks,
jim

By 803056

Date 08-26-2019 01:03

Base metals are grouped into "families" that have similar weldability. In the case of carbon and high strength low alloy steels the groupings are based on carbon equivalency. Other alloy systems are based on similar chemistry.

AWS structural welding code divides the base metals into groups. Generally, the higher the group number, the higher the preheat for a given temperature range. So, carbon steel and low alloy steels are grouped I through IV.

ASME uses P numbers, but again the carbon steels and low alloy steels are roughly grouped into P number groups. Austenitic stainless steels are P8, copper alloys are P3X, nickel alloys are contained in the P4X, titanium alloys in the P5X, where X is a 1,2,3, etc.
AWS B2.1 uses M numbers that follow the same grouping as ASME P numbers. NAVSEA uses S numbers.

F numbers originates for SMAW electrodes and indicated ease of use. F1 electrodes didn’t take a lot of skill, F2 a little more skill, F3 more skill yet, and F4 for the low hydrogen covered electrodes. The original low hydrogen electrodes were a ***** to weld with. So, a welder qualified with an F4 was alloyed to weld with an F4 and any electrode with a lower F number. One must remember what the letters ASME stand for; always, some times, maybe, and except. So now, a welder that is qualified with an F5 is only qualified for electrodes grouped as an F5 (heat and corrosion resistant electrodes and F1 electrodes. AWS structural welding code/steel only uses F1 through F4 for the electrodes for joining carbon steel and high strength low alloy electrodes.

A numbers are used by ASME and AWS B2.1 to designate the chemistry of the weld deposit.

The P, M, and S numbers, the F numbers, and the A numbers are called essential variables because if the numbers change, one must requalify the WPS.. What’s an essential variable? It is a variable that if changed affects the mechanical properties of the welded joint. When an essential variable is changed beyond the permissible range, a new coupon must be welded and the data recorded on a PQR.

Letters L, Q, R well I have to admit, you threw me a curve on those! ;)

Al