what does the P stand for when used in material identifiction such as, P-8 for stainless steel?

Answer 1

*Yes, its a welding position w.r.t. stainless steel.
[For number of different welding process,
some of the important procedures are listed below :
1. SS 304 to SS 304 (P8 to P8) using TIG process for
root and subsequent passes with back purging with
argon.Open butt type
2. SS 304 to SS 304 (P8 to P8) using TIG for root and
stabilising pass and subsequent passes with MMA.
Back purging for root and stabilising pass.
3.SS 304 to SS 304 (P8 to P8) using consumable weld
insert (EB type or V type) for root pass, and filler wire
for stabilising pass, back purging for both the Subsequent passes with TIG.
4. SS 304 to SS 304 (P8 to P8) using consumable weld
insert for room and stabilising pass with filler wire with
argon back/purging. Subsequent passes with MMA using coated electrodes.
5. SS 304 to SS 304 (P8 to P8) using coated
electrodes by MMA process.]

*AWS B2.1-1/8-006 Standard Welding Procedure Specification (SWPS) for Gas Metal Arc Welding of Carbon Steel to Austenitic Stainless Steel (M-1 to M-8, P-8 or S-8), 18 Through 10 Gauge, in the As-Welded Condition, with or without Backing Site License.

Answer 2

Per a discussion on this at an ASME Section IX Subcommittee meeting a year or two ago. Dr. D'or Doty, who probably was the longest subcommittee member at that time said that the "P" originally designated materials approved for welded "pressure" applications. The "S" numbers were developed sometime after P-Numbers and originally referred to materials approved by Code Cases for "structural" applications. That description would no longer be correct today, as there are many S-number materials that are used for pressure applications, such as piping.

The P-No classification was established by ASME Boiler and Pressure Vessel Code, SC IX to group metals having similar weldability characteristics.

The S-No was developed for metals that were not endorsed by ASME Boiler and Pressure Vessel Code, SC II. Again, the same premise applies regarding S-No classification as P-No classification.

The F-No is a classification for filler metals, similar to P and S-No classification.

The A-No define chemical composition for various filler metals and was established by AWS, years ago.

Answer 3

In addendum to the above answers, P8 is also a specific alloy of stainless tool steel used for injection molding. It features excellent wear resistance, and holds the very high polish necessary for good flow during injection. P20 is a much more common steel for that application, however.

Answer 4

P-8 is not a material type, It is the welding process for Austenitic stainless sheets from the AWS.

Answer 5

*It is difficult to search through google and yahoo!
Important to me is not abbreviation, but it is"P-numbers"
Go through:
http://books.google.com/books?id=AOCn1A3B4LoC&pg=PA195&lpg=PA195&dq=%22p+numbers%22&source=web&ots=whWdzdUWuE&sig=f4PBC3-1wRZBY80pKRYKmgu0Ktg#PPA195,M1