1
Preparation
For Welding
Joint
Design
The principal basic types
of joints used in TIG welding are the butt, lap, corner, edge, and tee. Almost
any
TIG weld you make will
be one or a combination of two or more of these basic types. Selection of the
proper
design for a particular
application will depend primarily on the following factors:
(a) Physical properties
desired in the weld.
(b) Cost of preparing the
joint and making the weld.
(c) Type of metal being
welded.
(d) Size, shape, and appearance
of the assembly to be welded.
Filler metal in the form
of a welding rod need not be used if proper reinforcement and complete fusion
of the
edges can be obtained
without it. The joint designs described below are but a few of the many that
can be
successfully TIG welded.
They do represent those most frequently used. Innumerable variations of these
types can be used to fulfill
special job requirements.
No matter what type of
joint is used, proper cleaning of the workpieces prior to welding is essential
if welds
of good appearance and
physical properties are to be obtained. On small assemblies, manual cleaning
with
a wire brush, steel wool,
or a chemical solvent is usually sufficient. For large assemblies, or for cleaning
on
a production basis, vapor
degreasing or tank cleaning may be more economical. In any case, be sure to
remove completely all
oxide, scale, oil, grease, dirt, rust, and other foreign matter from the work
surfaces.
Proper precautions should
be taken when using certain chemical solvents for cleaning purposes. The fumes
from some chlorinated
solvents (examples are trichlorethylene, and tetrachlorethylene) break down
in the
heat of an electric arc
and form a toxic gas. Avoid welding where such fumes are present. Furthermore,
these solvents vaporize
easily and prolonged inhalation of the vapor can be dangerous. Proper ventilation
equipment should be provided
to remove fumes and vapor from the work area.
