A Square tube is a hollow structure metallic tube with a
square geometry and has a widespread applications in the world. The tube is
also available in other shapes like circular and rectangular. Unlike pipe the
square tube has four sides with curved profile corners and are available in
wide range of material grades and dimensions. Hollow square tubes can be
applied to manufacture a variety of products with innovative designs and welding
is the foremost technique to join them. Below is the brief description on the
welding procedure of square tubing.
Joint Configuration
Square tubing can be done with different joint configuration
in different fashions. Most common way is to weld perpendicular pieces like
shown in the figure mainly applied in construction, framing etc. Placing one
piece upright to the other, we come across three types of joint configurations;
one butt joint, one fillet weld and two flare bevels. All of you are quite
familiar with these types of joints. On the outer side of the frame one side of
open end square tube piece is making butt joint with the wall of second tube
piece. Similarly on the inner side of frame, we get wall to wall fillet joint of
square tubes. Close study on the remaining other sides shows that curved edges
of lower tube are making a junction with side walls of upper tube which is the
flare bevel.
Joint Assembly
Once the pieces are in contact having the specific joints,
firm tie-in is required so that pieces may not displace from their exact
positions during welding. For this, tack weld are laid in order to fix the
pieces firmly. Tacking is primarily followed by suitable clamping.
Clamping
Slight pressure on the pieces to avoid any disposition. In
order to keep the joint assembly intact, suitable clamping tools are available
in market. Sometimes manual clamping is endorsed by welders by making temporary
supports. Tolerable pressure on the work piece allows good tacking.
Tack Weld
Before welding to commence, tack welds are applied for ease
of joining. Two ways are exercised to weld tacks. Some like to tack at the
center of joint sides and some tack at the corners. In former case,
misalignment of joint may occur if not clamped properly. It is a usual practice
to make next tack opposite to the first one to avoid any distortion. Once the
tacks are applied, the joint is ready for the complete welding.
Welding Pattern
In square tubing, welding variables like travel speed, heat
input matters a lot in attaining best results. In worst case, complexities may
arise which are difficult to deal with later on. Your job is to ensure the complete
penetration with suitable speed. If you go with too slower travel, your tubes
might be getting burnt. After filling flare bevels move ahead for the fillet
weld. Fill the weld with weaving bead
pattern. Side to side motion along the joint regulating the desired heat level.
Apply flat weld position on the butt joint. Here you have to deal with thin
edges of open end tube which could be burnt so adjust the travel speed
accordingly. Grind the weld curves if you want to see the tubes as a whole
piece.
Applications
- Square tubes are commonly used in automotive industry.
- In construction of buildings, bridges, framing, railing, poles.
- Office, supermarket, school, residential and home items, furniture, doors, windows, frames.
- Security and safety apparatus.
- They are applied in the manufacturing of transport containers.
- Production of equipment in large industries like mining, agriculture, transport, oil fields.
- Now a days commonly using in production of towers for telecommunications industry.