Figure 15-31.--Various types of welded joints.
convenience for maintenance. The material and design
techniques. There are three general classes of welded
of flanges are determined by service conditions.
joints: butt-weld, fillet-weld, and socket-weld (fig.
Welded joints normally permit welding from both
sides. If not, backing rings should be used to ensure
The selection of piping material, size, and wall
complete weld penetration.
thickness was discussed earlier in this chapter. The type
of service and flow rates determine material and size.
Brazed joints must have sleeves or sockets. The
Internal pressure determines wall thickness or strength
fittings must have preinserted rings of silver brazing
of piping. If the strength is not to be exceeded, do not
alloy. Also, the welded and brazed joints must meet the
subject piping to any unusual stresses, such as would
requirements established by MIL-STD 22. Examples
result from misalignment, vibration, improperly
of silver-brazed joints are shown in figure 15-32.
adjusted hangers, supporting chain falls, and so on.
Flanges are installed in piping systems to allow
All common piping materials will expand when
ready removal of piping. This provides for portability
heated and contract when cooled. If piping is confined
of machinery and equipment, access to equipment, and
Figure 15-32.--Silver-brazed joints.