Sunday 1 September 2013

Stitch / Intermittent Welding

Stitch welding

 Where to use is the question most of us have.

Let us define it first
  • it is the process of welding to base materials in many short sections.
  • This process gives a weld less strength
  • This keeps the material from warping too much since you use half as much heat
  • It is also known as intermittent welding.


According to AWS (American Welding Society), Its defined as Welding that does not require one continuous weld along the length of the entire joint. Intermittent welds are shorter welds, spaced evenly along the joint.

Intermittent weld can be classified into two types namely

Chain Intermittent Weld
            A type of intermittent weld that requires a sequence of welds on each side of the joint that line up evenly with each other..

Staggered Intermittent Weld.
            A type of intermittent weld that requires a sequence of welds on each side of the joint that do not line up evenly with each other.


Welding symbols for Intermittent Weld:



Intermittent Weld Design Conditions as per Indian Standards:
  • Intermittent fillet welds may be provided where the strength required is less than that can be developed by a continuous fillet weld of the smallest allowable size for the parts joined.
  • The length of intermediate welds should not be less than 4 times the weld size with a minimum of 40 mm. 
  • The clear spacing between the effective lengths of the intermittent welds should be less than or equal to 12 times the thickness of the thinner member in compression and 16 times in tension; in no case the length should exceed 20 cm. 
  • Chain intermittent welding is better than staggered intermittent welding. 
  • Intermittent fillet welds are not used in main members exposed to weather. For lap joints, the overlap should not be less than five times the thickness of the thinner part. 

From the above extracts, we can conclude that it can be used in thinner materials where warping is a major issue and should not be used in main members which are exposed to weather. Depending on the strength criteria and connection cost, we can choose staggered welding.

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