ShieldGules (Crimson), on a bend between a spur gear and a feather palm tree Or, three torteaux of the field.
CrestFrom a wreath Or and Gules (Crimson), a shell palewise Sable charged with four mullets in pale of the second, flanked on either side by two pheons Proper.
MottoSERVICE, NOT GLORY.
ShieldThe background is crimson and the bend is yellow, the colors of the Ordnance Branch. The torteaux, simulating cannon balls, allude to the numerical designation of the unit. The spur gear represents maintenance, and the palm tree is characteristic of the flora of the countryside where the battalion was organized, i.e., Southern California.
CrestCrimson and yellow are the colors traditionally used by Ordnance. The shell suggests ammunition, highlighting the mission of the battalion as explosive and ammunition disposal. It is charged with four stars symbolizing the unit's decorations. The two pheons represent the organization's service in World War II and Vietnam.
The coat of arms was originally approved for the 3d Ordnance Battalion on 14 September 1942. It was rescinded on 14 April 1955. It was reinstated for the 3d Ordnance Battalion on 20 May 1997. The insignia was amended to include a crest on 27 July 1998.