TEST OR INSPECTION

a. Properly clamp or tack weld parts to resist shrinkage.

b. Separate or preform parts sufficiently to allow for shrinkage of welds.

c. Peen the deposited metal while still hot.

a. Support parts of structure to be welded to prevent buckling in heated sections due to weight of parts themselves.

b. Preheating is desirable in some heavy structures.

c. Removal of rolling or forming strains before welding is sometimes helpful.

a. Study the structure and develop a definite sequence of welding.

b. Distribute welding to prevent excessive local heating.

a. Slight movement of parts during welding will reduce welding stresses.

b. Develop a welding procedure that permits all parts to be free to move as long as possible.

a. Make weld in as few passes as practical.

b. Use special intermittent or alternating welding sequence and backstep or skip welding procedure.

c. Properly clamp parts adjacent to the joint. Use backup fixtures to cool parts rapidly.

Peen each deposit of weld metal. Stress relieve finished product at 1100 to 1250°F (593 to 677°C) 1 hour per 1.0 in. (25.4 cm) of thickness.

Distribute heat input more evenly over full length of seam.

Weld rapidly with a minimum heat input to prevent excessive local heating of the plates adjacent to the weld.

a. Do not have excessive space between the parts to be welded. Prepare thin plate edges with flanged joints, making offset approximately equal to the thickness of the plates. No filler rod is necessary for this type of joint.

b. Fabricate a U-shaped corrugation in the plates parallel to and approximately 1/2 in. (12.7 mm) away from the seam. This will serve as an expansion joint to take up movement during and after the welding operation.

a. Use special welding sequence and backstep or skip procedure.

b. Preheat material to relieve stress.

Properly clamp parts adjacent to the joint. Use backup fixtures to cool parts rapidly.

a. Ensure the use of the proper welding technique for the welding rod used.

b. Do not use excessive heat.

c. Use a uniform weave and welding speed at all times.

Use a welding rod designed for the type of weld being made.

Prepare all joints properly.

Redesign the structure or modify the welding procedure in order to eliminate rigid joints.

Do not use too small a weld between heavy plates. Increase the size of welds by adding more filler metal.

a. Do not make welds in string beads. Deposit weld metal full size in short sections 8.0 to 10.0 in. (203.2 to 254.0 mm) long. (This is called block sequence.)

b. Welding sequence should be such as to leave ends free to move as long as possible.

c. Preheating parts to be welded sometimes helps to reduce high contraction stresses caused by localized high temperatures.

Make sure welds are sound and the fusion is good.

Prepare joints with a uniform and proper free space. In some cases a free space is essential. In other cases a shrink or press fit may be required.

a. Modify welding procedure to balance weave of bead and rate of welding rod deposition, using proper tip size.

b. Do not use too small a welding rod.

a. Avoid excessive and nonuniform weaving.

b. A uniform weave with unvarying heat input will aid greatly in preventing undercut in butt welds.

Do not hold welding rod too near the lower edge of the vertical plate when making a horizontal fillet weld, as undercut on the vertical plate will result.

a. Be sure to allow the proper free space at the bottom of the weld.

b. Deposit a layer of weld metal on the back side of the joint, where accessible, to ensure complete fusion at the root of the joint.

a. Select proper sized welding rod to obtain a balance in the heat requirements for melting welding rod, breaking down side walls, and maintaining the puddle of molten metal at the desired size.

b. Use small diameter welding rods in a narrow welding groove.

Use sufficient heat input to obtain proper penetration for the plate thickness being welded.

Welding speed should be slow enough to allow welding heat to penetrate to the bottom of the joint.

Use welding rod of proper chemical analysis.

a. Avoid overheating molten puddle of weld metal.

b. Use the proper flame adjustment and flux, if necessary, to ensure sound welds.

a. Use the multilayer welding technique to avoid carrying too large a molten puddle of weld metal.

b. Puddling keeps the weld metal longer and often ensures sounder welds.

Modify the normal welding procedure to weld poor base metals of a given type.

Avoid welding rods producing air-hardening weld metal where ductility is desired. High tensile strength, low alloy steel rods are air-hardened and require proper base metal preheating, postheating, or both to avoid cracking due to brittleness.

Do not use excessive heat input, as this may cause coarse grain structure and oxide inclusions in weld metal deposits.

Welds may absorb alloy elements from the patent metal and become hard. Do not weld a steel unless the composition and characteristics are known.

a. Adjust the flare so that the molten metal does not boil, foam, or spark.

b. A single pass weld maybe more brittle than multilayer weld, because it has not been refined by successive layers of weld metal.

When welding in narrow grooves, use a welding rod small enough to reach the bottom.

Use sufficient heat to melt welding rod and to break down sidewalls of plate edges.

Be sure the weave is wide enough to melt the sides of the joint thoroughly.

The deposited metal should completely fuse with the side walls of the plate metal to form a consolidated joint of base and weld metal.

Select welding rods with the proper corrosion resistance properties which are not changed by the welding process.

a. Use the proper flux on both parent metal and welding rod to produce welds with the desired corrosion resistance.

b. Do not expect more from the weld than from the parent metal. On stainless steels, use welding rods that are equal to or better than the base metal in corrosion resistance.

c. For best corrosion resistance, use a filler rod whose composition is the same as the base metal.

When welding 18-8 austenitic stainless steel, be sure the analysis of the steel and the welding procedure are correct, so that the welding process does not cause carbide precipitation. This condition can be corrected by annealing at 1900 to 2100°F (1038 to 1149°C).

Certain materials such as aluminum require special procedures for thorough cleaning of all slag to prevent corrosion.

In welding on medium carbon steel or certain alloy steels, the fusion zone may be hard as the result of rapid cooling. Preheating at 300 to 500°F (149 to 260°C) should be resorted to before welding.

Multilayer welds will tend to anneal hard zones. Stress relieving at 1000 to 1250°F (538 to 677°C) after welding generally reduce hard areas formed during welding.

The use of austenitic welding rods will often work on special steels, but the fusion zone will generally contain an alloy which is hard.

a. Properly tack weld or clamp parts to resist shrinkage.

b. Separate or preform parts so as to allow for shrinkage of welds.

c. Peen the deposited metal while still hot.

a. Preheating is desirable in some heavy structures.

b. Removal of rolling or forming strains by stress relieving before welding is sometimes helpful.

a. Study structure and develop a definite sequence of welding.

b. Distribute welding to prevent excessive local heating.

a. Slight movement of parts during welding will reduce welding stresses.

b. Develop a welding procedure that permits all parts to be free to move as long as possible.

a. Make weld in as few passes as practical.

b. Use special intermittent or alternating welding sequence and backstep or skip procedures.

c. Properly clamp parts adjacent to the joint. Use backup fixtures to cool parts rapidly.

a. Peen each deposit of weld metal.

b. Stress relieve finished product at 1100 to 1250°F (593 to 677°C) 1 hour per 1.0 in. (25.4 cm) of thickness.

Select electrode with high welding speed and moderate penetrating properties.

Weld rapidly to prevent excessive local heating of the plates adjacent to the weld.

a. Do not have excessive root opening in the joint between the parts to be welded.

b. Hammer joint edges thinner than the rest of the plates before welding. This elongates the edges and the weld shrinkage causes them to pull back to the original shape.

a. Use special intermittent or alternating welding sequence and backstep or skip procedure.

b. Preheat material to achieve stress.

Properly clamp parts adjacent to the joint. Use backup fixtures to cool parts rapidly.

a. Ensure the use of the proper welding technique for the electrode used.

b. Do not use excessive welding current.

c. Use a uniform weave or rate of travel at all times.

Use an electrode designed for the type of weld and base metal and the position in which the weld is to be made.

Do not make fillet welds with downhand (flat position) electrodes unless the parts are positioned properly.

Prepare all joints properly.

Redesign the structure and modify the welding procedure in order to eliminate rigid joints.

Do not use too small a weld between heavy plates. Increase the size of welds by adding more filler metal.

a. Do not make welds in string beads. Deposit weld metal full size in short sections 8.0 to 10.0 in. (203.2 to 254.0 mm) long. (This is called block sequence.)

b. Welding sequence should be such as to leave ends free to move as long as possible.

c. Preheating parts to be welded sometimes helps to reduce high contraction stresses caused by localized high temperature.

d. Fill all craters at the end of the weld pass by moving the electrode back over the finished weld for a short distance equal to the length of the crater.

Make sure welds are sound and the fusion is good. Be sure arc length and polarity are correct.

Prepare joints with a uniform and proper root opening. In some cases, a root opening is essential. In other cases, a shrink or press fit may be required.

Use a moderate welding sent and do not try to weld at too high a speed.

a. Do not use too large an electrode. If the puddle of molten metal becomes too large, undercut may result.

b. Excessive width of weave will cause undercut and should not be used. A uniform weave, not over three times the electrode diameter, will aid greatly in preventing undercut in butt welds.

c. If an electrode is held to near the vertical plate in making a horizontal fillet weld, undercut on the vertical plate will result.

a. Electrodes should be used for welding in the position for which they were designed.

b. Be sure to allow the proper root openings at the bottom of a weld.

c. Use a backup bar if possible.

d. Chip or cut out the back of the joint and deposit a bead of weld metal at this point.

a. Do not expect excessive penetration from an electrode.

b. Use small diameter electrodes in a narrow welding groove.

Use sufficient welding current to obtain proper penetration. Do not weld too rapidly.

Control the welding speed to penetrate to the bottom of the welded joint.

Some electrodes inherently produce sounder welds than others. Be sure that proper electrodes are used.

A weld made of a series of string beads may contain small pinholes. Weaving will often eliminate this trouble.

Puddling keeps the weld metal molten longer and often insures sounder welds.

In some cases, the base metal may be at fault. Check this for segregations and impurities.

Bare electrodes produce brittle welds. Shielded arc electrodes must be used if ductile welds are required.

Do not use excessive welding current, as this may cause coarse-grained structure and oxidized deposits.

a. A single pass weld may be more brittle than a multilayer weld because its microstructure has not been refined by successive layers of weld metal.

b. Welds may absorb alloy elements from the parent metal and become hard.

c. Do not weld a metal unless the composition and characteristics are known.

When welding in narrow groove joints use an electrode small enough to properly reach the bottom of the joint.

a. Use sufficient welding current to deposit the metal and penetrate into the plates.

b. Heavier plates require higher current for a given electrode than light plates.

Be sure the weave is wide enough to melt the sidewalls of the joint thoroughly.

The deposited metal should fuse with the base metal and not curl away from it or merely adhere to it.

a. Bare electrodes produce welds that are less resistant to corrosion than the parent metal.

b. Shield arc electrodes produce welds that are more resistant to corrosion than the parent metal.

c. For the best corrosion resistance, use a filler rod whose composition is similar to that of the base metal.

Do not expect more from the weld than you do from the parent metal. On stainless steels, use electrodes that are equal to or better than the parent metal in corrosion resistance.

When welding 18-8 austenitic stainless steel, be sure the analysis of the steel and welding procedure is correct, so that the welding does not cause carbide precipitations. Carbide precipitation is the rising of carbon to the surface of the weld zone. This condition can be corrected by annealing at 1900 to 2100°F (1038 to 1149°C) after welding. By doing this corrosion in the form of iron oxide, or rust, can be eliminated.

Certain materials, such as aluminum, require careful cleaning of all slag after welding to prevent corrosion in service.

In medium carbon steel or certain alloy steals, the heat affected zone may be hard as a result of rapid cooling. Preheating at 300 to 500°F (149 to 260°C) should be resorted to before welding.

a. Multilayer welds will tend to anneal hard heat affected zones.

b. Stress relieving at 1100 to 1250°F (593 to 677°C) after welding will generally reduce hard areas formed during welding.

The use of austenitic electrodes will often be successful on special steels, but the heat-affected zone will generally contain an alloy which is hard.

a. Make sure the ground is properly located on the work. Placing the ground in the direction of the arc deflection is often helpful.

b. Separating the ground into two or more parts is helpful.

c. Weld toward the direction in which the arc blows.

d. Hold a short arc.

e. Changing the angle of the electrode relative to the work may help to stabilize the arc.

f. Magnetic blow is held to a minimum in alternating current welding.

Select the proper type of electrode.

Use a short arc but do not use excessive welding current

a. Paint parts adjacent to welds with whitewash or other protective coating. This prevents spalls from welding to parts, and they can be easily removed.

b. Coated electrodes produce larger spalls than bare electrodes.