Submerged Arc Welding Technical Handbook - Esab

Narrow gap welding - complete
ESAB solution for repetitive
fabrication of thick sections
Narrow gap welding becomes attractive with heavy wall
thickness sections in repetitive fabrication, e.g. the
fabrication of foundation piles for the offshore and wind
energy segments. ESAB provides a total solution which
includes specialised welding equipment, welding
consumables and automation.
The main advantage of narrow gap welding is the
greatly reduced weld volume in very thick sections,
which results in weld cycle time reduction. Furthermore,
the one-sided butt arrangement makes it easier to
avoid linear misalignments, as opposed to two-sided
joints (X prep.).
When considering this process, it must be taken into
account that it involves a large initial investment, as well
as the more expensive machining of narrow gap joint
preparations. These need to be fully justified by cost
analysis, in which ESAB can assist.
It is essential that the process operates free from
inconsistencies. The side-wall wetting must be perfect
in order to avoid lack of fusion in the following layer.
Slag is required to be self releasing, even on
preheated high strength steels.
OK Flux 10.62 meets all these criteria, and is also very
suited when low hydrogen is required to avoid cold
cracking. It is an EN 760 H5 classified flux which is
suited for low-temperature steels, due to its high
basicity.
Effect of Configuration on Weld Joint Area - Based on 150 mm Thickness
Relative Joint Area (%)
160
All Joints have 5 mm land
Reinforcement is not included in the calculation
140
120
Narrow gap welding can be single or tandem wire;
both requiring specially designed welding heads
(swords), narrow enough to fit into the joint
preparation. All heads - including types with contact
jaws, flux supply, flux recovery or tactile sensors - are
insulated. This is to avoid unwanted arcing, when
the equipment accidentally moves against the joint
edges. Typical wire diameters are 3 and 4 mm. Up to
350 mm thickness can be welded with the standard
ESAB head, but special versions are available for
thicker sections.
100
80
60
40
20
0
2 degree Narrow
Gap
50 degree DY 60 degree DY 50 degree Y 60 degree Y
In 150 mm material thickness, 5 mm land - reinforcement not included.
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