American Welding Society have between their publications one of can be helpful for made the work efficient and is a great tool for the new inspector, trainee, learner, student or some people that work with symbology.
I'm talking about the AWS A2.4 "Standard Symbols for Welding, Brazing, and Nondestructive Examination." AWS A2.4 provide us terms and definitions for welding, basic welding symbols, symbols by welding technique and Nondestructive examination symbols.
Also, AWS A2.4 have a lot of images and tables for reference.
The scope for AWS A2.4 provides a system for indicate the Welding, brazing and NDT requirements. The system includes stipulations for the graphic representation of welding, brazing and NDT with alignments for specify the location and extension of the application.
The optional elements and complementary symbols provide us a medium for specify additional requirements.
Jorge T. Reyna´s Blog (NDT, Welding, Concrete & Coatings)