The type of door seam is an important element in the door construction. When selecting it, you should consider the following aspects:
- Building type.
- Frequency level.
- Abuse level.
- Security level.
Openings in high frequency, high abuse or high security areas require a full flush continuously welded door. Since the edge of the door is reinforced and continuously welded, a door that is fully continuously welded is stronger than a standard lock seam on edge door. A lock seam on edge door is only spot welded at the top and the bottom of the door edge, without edge reinforcements.
The term “full flush” means there is no visible seam on the face of the door. A vertical seam may be permitted on the door edges if the door is not qualified as a seamless door. A seamless door has no visible seams on the vertical edges, for more esthetic value.
Also, the door should have been tested per the physical endurance standard ANSI A250.4: Test Procedure and Acceptance Criteria for — Physical Endurance for Steel Doors, Frames and Frame Anchors. A series of cycle and twist test are performed to verify the strength of the door. Level A (1 000 000 cycles) is recommended for extra heavy duty applications, Level B (500 000 cycles) is recommended for heavy duty applications and Level C (250 000 cycles) is recommended for standard duty applications.