There are several types non-conforming fabrication on stiffeners, the most common of which are mis-located stiffeners, incorrect hole placement, and improper stiffener to flange attachment. Repairs will vary, depending on the non-conformance and/or type of stiffener.
Timing is important when making decisions about repairs. If an error is noticed after the stiffener has been tacked into place, but before it has been completely welded, it might be possible to remove the stiffener and place it in the correct location. After the stiffener has been fully welded, removal of the stiffener is a more difficult solution.
Changes in design requirements in recent years have created additional possibilities for errors with stiffeners. Most states require diaphragm connection plates to be connected to the tension flange. State bridge manuals vary in opinion on welding the connection plate to the tension flange. The fabricator should always thoroughly check the contract documents to determine if welding to the tension flange is acceptable. Deviations in the compression flange attachment generally have simpler solutions than deviations in the tension flange. If a hole is inadvertently drilled in a compression flange, the hole may be either filled with a bolt, or a positive connection, similar to a tension flange connection, may be made, depending on the number and location of the misdrilled holes.
Repairs to misdrilled holes in tension flanges typically require the fabrication of a new positive connection to the flange depending on the location of the holes.
Caution should be exercised about rushing to repair a misdrilled hole. Both the QC and QA inspection personnel should carefully verify several factors before completing any repairs. Some items to be verified include:
a) Tension or compression flange verified with design plans and/or shop drawings
b) Edge distances
c) Clearances
d) Hole Spacing
e) Hole Size
Occasionally, a diaphragm connection plate or stiffener is welded to a tension flange where welding is not allowed or is all together prohibited. Depending on the location and extent of the welding done, inspectors will sometimes require the fabricator to break the weld, and install the bolted connection in accordance with the design plans. If breaking the weld is not acceptable, then an alternative solution may be required. Solutions to these types of problems are still under development.