Direct Answer
A bulletin drawing (also called a clarification drawing or SK — sketch — from the engineer) is a supplemental engineering sketch or drawing that clarifies, modifies, or adds detail to the original design documents. It is typically issued in response to an RFI and supersedes any conflicting information in the original drawings. Process it by updating the detailing model, revising affected shop drawings, and resubmitting for approval.
Full Explanation
Engineering bulletins have formal status — they become part of the contract documents and the detailer must incorporate them into the model. The chain: (1) RFI question submitted. (2) Engineer responds with a bulletin drawing (often a PDF sketch numbered 'SK-01', 'SK-02', etc.). (3) The detailer reviews the bulletin against the model, identifies affected members, and modifies the model. (4) Affected piece mark drawings are reissued with a revision cloud showing the change. (5) Revised drawings are resubmitted as R1, R2, etc. (6) Engineer re-approves. (7) Shop floor receives IFC revised drawings.
What This Means for Your Shop
Bulletin drawings that arrive after steel has been fabricated are potential change orders. Assess the bulletin's impact on already-fabricated members immediately upon receipt — don't wait until erection to discover you have wrong material.
Common Mistakes
Filing a bulletin drawing without assessing its impact on the production schedule. A bulletin that revises connection details for 40 already-fabricated beams needs to trigger an immediate production hold, not a 'we'll deal with it later' response.
Recommended Process
When a bulletin is received, send it to the detailer immediately with instructions to assess the impact on the current model. Receive a bulletin impact report within 24 hours identifying: how many piece marks are affected, how many are already fabricated, and the cost of rework. Submit a COP within 5 business days.