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2.5. Correction of Fabrication Errors
No, fabrication errors don’t always require repair. Because the human element is involved in all phases of structural steel fabrication, material inadvertently may be cut to the wrong length, holes may be misplaced, parts may be located incorrectly or notches or gouges may occur. However, many such errors or deviations need not be altered or repaired and are acceptable without change or penalty to the structure or its end use. Furthermore, some repair work may be more detrimental than leaving the piece unrepaired. In general, the structural engineer of record (SER) should evaluate the deviation and whether it would be detrimental to the end use of the product.
In some cases, repair will be required and can usually be made so that the member will meet all performance criteria. Corrective measures to meet the requirements of shop drawings and specifications may generally be made by the fabricator during the normal course of fabrication, using qualified personnel and procedures that meet AISC and AWS specifications. Such action is considered to be a part of the fabricator's quality control program and should not require either notification of, or approval from, the owner or SER. However, in cases where major work is involved (cutting or removal of welded members from a welded assembly, modification of design, deviation from critical dimensions, etc.), the SER should be consulted and a plan of corrective action agreed upon.
When material is short of the minimum required length, welded splices or deposited weld metal—when applied with appropriate welding procedures and specified material—should be permitted. However, the approval of the SER is required in such cases.
Generally, mislocated fastener holes are not detrimental to the strength of a member if the remaining effective net section is adequate for the loads. As such, they may be left open or filled with bolts.
If required, mislocated holes can be structurally repaired in accordance with Clause 7.25.5 of AWS D1.1/D1.1M. Attention should be paid to the Commentary to Clause 7.25.5, as it describes a rather involved process that can be used for such repairs. The process involves considerable gouging and welding, and therefore considerable heat input. As with all repairs, the benefits of the repair should be carefully weighed against the potential problems that the repair itself could cause.
Plug welding of mislocated holes is not an acceptable structural repair. If a bolt hole is mislocated by a small amount—say, less than a bolt diameter—it is often possible to adjust the connection material to accommodate the error.
When detail parts are placed in error, minor mislocations should be investigated to determine if relocation is necessary. When relocation is necessary, such as when dimensions are critical, the error is major or the incorrectly placed part is visually unacceptable under an AESS requirement, the incorrectly placed part should be removed. For a welded detail, flame cutting, gouging, chipping, grinding or machining may be required. Care should be taken to avoid damage to the main material of the associated member. The surface of the main material should be ground smooth and repaired, if necessary, as indicated in 2.2.6 and 2.2.7.
During the course of erection, it occasionally becomes necessary to ream holes so fasteners can be installed without damage to the threads, resulting in a hole that is larger than normal or elongated. The hole types recognized by the AISC and RCSC Specifications are standard, oversized, short-slotted, and long-slotted, with nominal dimensions as given in the AISC Specification Table J3.3.
The AISC Code of Standard Practice Section 7.14 Commentary states: "The term ‘moderate’ refers to the amount of reaming, grinding, welding or cutting that must be done on the project as a whole, not the amount that is required at an individual location. It is not intended to address limitations on the amount of material that is removed by reaming at an individual bolt hole, for example, which is limited by the bolt-hole size and tolerance requirements in the ASNI/AISC 360 and RCSC Specification." Note that reamed holes must meet the provisions for minimum spacing and minimum edge distance in AISC Specification Sections J3.3 and J3.4, respectively.
When more major misalignments occur, it is indicated in the AISC Code of Standard Practice Section 7.14 that they are “promptly reported to the [owner] and the fabricator by the erector, to enable the responsible entity to either correct the error or approve the most efficient and economical method of correction to be used by others.”