AWWA C206 — Field Welding of Steel Water Pipe

AWWA C206 covers bell-and-spigot lap joints (the most common field joint for water pipe), butt joints, and flange connections. For lap joints, the standard specifies minimum overlap dimensions based on pipe diameter and requires both inside and outside fillet welds for pipe 24" and larger. Smaller diameters may use outside welds only.

Per AWWA C206 Section 5.2, welders must be qualified in accordance with ASME BPVC Section IX or AWS D1.1. The qualification test must be in the position(s) to be used in production and with the process and electrode type specified in the WPS. Qualification records must be available at the job site.

AWWA C206 Section 7 requires visual inspection of all welds. Radiographic (RT) or ultrasonic (UT) testing may be specified by the purchaser — many SoCal agencies require 10–100% RT depending on pipe diameter and criticality. The standard defers specific RT acceptance criteria to ASME or AWS, as specified in the contract.

AWWA C206 serves as a baseline standard that agencies modify through their own specifications. For example, SDCWA requires 100% RT for butt welds on pipe ≥36" diameter, while MWD requires 100% RT on all butt welds regardless of size. Agency specs typically add requirements on top of C206, not replace them.