WELDING CONSUMABLES
There are 3-types of electrode:
- Cellulosic
- Rutile
- Basic
CELLULOSIC ELECTRODE:
- It cannot be baked
- It has forceful arc
- Risk of hydrogen cracking
- High toughness at low temperature cannot be achieved
- Used for root runs
- Used for stove pipe welding.
RUTILE ELECTRODE:
- It cannot be baked
- Risk of hydrogen cracking
- Smooth &stable arc
- High toughness at low temperature cannot be achieved
- Used for steel thickness ≤ 13mm
BASIC ELECTRODE:
- Can be baked upto 350 degree centigrade
- It has got good sub-zero toughness upto -90 degree centigrade
- Surface profile will be convex
- Slag removal require more effort
- It is used to avoid hydrogen cracking.
ELECTRODE DESIGNATION:
E 46 3 1Ni D 5 4 H5
E = Covered electrodes
46 = Toughness / Tensile & Yield Strength
3 = Impact energy
1Ni = Chemical Composition
D = Type of coating
5 = Type of current & Metal recovery %
4 = Welding Position
H5 = Hydrogen content
The first five parts of code are important and compulsory comprising:
E = Covered electrodes
46 = Tensile & Yield Strength
3 = Impact energy
1Ni = Chemical Composition
D = Type of coating
MCQ IMPORTANT POINTS
- The type of electrode used for ‘stove pipe’ welding for overland pipeline construction is Cellulosic.
- The chemical composition of the weld metal is controlled by the additions in the flux of electrode.
- A low hydrogen will have basic type of covering.
- A typical baking temperature range of basic coated electrode is 350 degree centigrade.
- A basic covering electrode gives high weld metal toughness at -50 degree centigrade.