molybdenum alloy steels that have over 35 percent
All welds in P-2 piping must be inspected during
the hydrostatic test of the piping and must be
radiographed if it is required by the plans or
P-LT CLASS PIPING
In general, the manual shielded metal-arc
process is used for the shipboard welding of P-LT
submarines, all silver-brazed joints 1/2 inch ips and
class piping that is 0.109 inch or more in wall
above must be ultrasonically tested.
thickness and for the shop welding of P-LT class
piping that is 0.083 inch in wall thickness.
WELD SYMBOLS AND
The tests and inspections for P-LT class piping
are generally the same as those for P-l class piping.
Use the applicable documents that cover joint
Special symbols are used on drawings to show
designs, welding procedures, stress-relieving, and
the kinds of welds to be used. These symbols have
nondestructive tests and inspections for each job as
been standardized by the American Welding Society
and the Department of Defense. The basic
reference in this field for Navy welders is the
P-3 CLASS PIPING
American Welding Society Standard, AWS A2.4-79.
AWS A2.4-79 supersedes AWS A2.0-68, which
The requirements for P-3 class piping are
formerly was the basic reference for the Navy
equally as important as those for P-l, P-2, and P-LT
welders. Although there is no need for you to
piping. P-3 piping systems are assembled by silver
memorize all the welding symbols given in AWS
brazing. Filler materials and fluxes must be selected
A2.4-79, you should be familiar with the basic weld
on the basis of the metals to be joined.
symbols and with the standard location of all eight
elements of a welding symbol.
The fabrication and inspection of all P-3 piping
must be according to NAVSEA 0900-LP-001-7000,
The distinction between a weld symbol and a
Fabrication and Inspection of Brazed Piping Systems.
welding symbol should be noted. A WELD
After the joint is cooled, all accessible sections of
SYMBOL is a basic weld symbol used to indicate
the joint are to be cleaned to remove any scale or
the type of weld. Thus, the basic weld symbols
flux that may be present.
shown in figures 7-24 and 7-25 are weld symbols.
The supplementary weld symbols shown in figure
In addition to being hydrostatically tested, all
7-26 are used when necessary in connection with the
silver-brazed joints in P-3 class piping 2 inches ips
basic weld symbols. In figures 7-24, 7-25, and 7-26,
and over must be ultrasonically tested. On
view A, shows the symbols that were listed in AWS
Figure 7-26.--Supplementary weld symbols.
Figure 7-24.--Basic arc and gas weld symbols.