Thickness (THK): All thickness dimensions are considered nominal unless otherwise specified. In cases where a minimum thickness is required, this should be clearly indicated on the inquiry or order.
Dish Radius (DR): ASME and standard flanged and dished heads are formed with an inside dish radius equal to the outside diameter of the head. Also, it is possible to form heads 30" OD and above with a dish radius equal to 80% of the diameter.
Straight Flange (SF): 1 1/2" straight flange is considered standard for most material thicknesses. Flanges up to 3" can be supplied on some heads, providing material thickness is suitable. Heads under 3/16" thickness are supplied with a 1" straight flange.
Center Hole: Heads 18" and larger are formed with a 1 3/8" - 1 1/2" maximum center hole. When a center hole is not desired it can be plugged and X-rayed.
Knuckle Radius (KR): The knuckle radius will be a minimum of 6% of the diameter on ASME code heads.
Inside Depth of Dish (IDD): This is the depth of the head at its center, including the knuckle radius, but not the straight flange.
Finished Inside Depth (FID): This is the depth of the head at its center, including both the knuckle radius and the straight flange.
Overall Height (OAH): The total height of the head is obtained by adding the Finished Inside Depth and Thickness. Both the straight flange and overall height cannot be guaranteed.