For general structural work a less elaborate groove in the end of the branch or alternatively a slight flattening of the branch will bring the pipe surfaces within sufficient proximity to ensure a strong structural joint.

Where the branch pipe is used as a strut with little lateral strength required then an even flatter section to produce a T Joint can be tolerated.

It is sometimes feasible to also substitute fillet welds for butt welds in odd shaped sections thus reducing welding difficulties. Pipes can be slit to take a gusset or in say railway line section, a plate inserted between the two.

When bending larger diameter pipe (over 30mm) a cold bend is not often practical and wrinkle bending can produce a desired shape without difficulty. The inner side

of the curve of pipe is heated on a small band and when at red heat pressure is applied. The heat is next applied a little further along the pipe and the bend repeated, the process being continued until the desired curve is obtained.
 

Controlling Penetration by Position

When using a small electrode on heavy sections, a greater heat input, penetration and heavier weld can be achieved using the vertical position and welding with the up technique.

Similarly on light sheet metal, welding down with sheet in the vertical position reduces the penetration permitting attractive solid welds to be made in quite light sheet metal. The sheet should be tacked at very frequent intervals and where possible designed to have joints meeting over a heavier strut.

In welding deep into poorly prepared or square preparations, electrodes of the basic coated type (such as Austarc 16TC) or producing a minimum of slag (such as Austarc I I) are the best choice. With basic electrodes, the operator can puddle and virtually weld through the slag without the same danger of lack of fusion and slag entrapment as with normal GP types. With the high cellulose E.4111 types the minimal slag produced and high arc forced permits greater penetration into the unprepared joint.

The process of hard surfacing permits the placement of a highly alloyed or special characteristic alloy over a relatively cheap base material which provides the bulk and strength of the component. Even a small amount of wear may render a complete component useless for further work. Welding enables the rebuilding to size of worn components, thus extending their service life at a fraction of the price of a new component.

Wear action may take different forms. Rock crushing equipment involves both impact and abrasions. Grader blade side cheeks have simple abrasion over a surface. Ploughshares have similar problems, but require to retain a sharp cutting edge. A water boring tool requires a combination of cutting edges which can withstand both impact and abrasion and reaming faces that must take pure sliding abrasion, often of great severity. Metal to metal wear and corrosive conditions offer different problems. Different conditions are better served by different classes of materials.

Page 21 shows the WIA range of hard surfacing and some special alloy electrodes, together with their main characteristics and applications. Their suitability or importance in various fields in Groups 1, 2, and 3, Group 1 being highly desirable, Group 2 useful and Group 3 required for some special applications only.

The following general rules and techniques are useful in ensuring satisfactory welding and service life, and pages 20 and 21 show some typical techniques.

Hard surfacing electrodes are ideally applied on the lowest practicable amperage to reduce dilution of the special alloy to a minimum. Always avoid excessive penetration, where possible two or three layers achieve a superior alloy to one layer, although some of the harder alloys prove too brittle for multiple layer buildup.

Weaving at low amperage can be employed to give a flatter bead with low dilution. This technique is often used for areas subject to severe abrasion. When using the low dilution ‑ low penetration techniques of hard surfacing, greater care must be paid to cleanliness of the weld area to ensure fusion and bonding. Grind off rust for best results.

Where sharp cutting edges are required to be maintained for efficient working, such as in ripper points, scarified teeth, ploughshares, etc., apply the wear resistant layer on one surface of the tool only. The softer material underneath will wear faster, retaining the cutting edge with a self sharpening effect.

For large areas working in clay, etc. a latticework of beads will give an economical extension of life, the raised beads protecting the area against continuous scraping over the surface. The dot technique gives similar action in different material, such as quarry work. The individual mounds of weld metal formed by small concentrated circular welds do not pose stress or cracking problems yet provide excellent protection to the main body.

Peeving ‑ hammering with a ball hammer‑during cooling will help relieve shrinkage stresses and minimise cracking in beads and pads. Some very hard alloys will crack, giving in a natural stress relieving treatment. This is not critical in broad surface applications, but cracks are undesirable in load bearing machinery components or edges subject to bending and in such cases tougher weld metals should be selected.