A clear drawing can prevent a quotation from being based on an obsolete or incomplete requirement. Mark the approved revision and identify which dimensions are mandatory before requesting manufacture.
Identify the controlling document
Put the drawing number, revision, date and units on the document. If the material list and drawing disagree, identify the conflict explicitly and request a written resolution. Do not silently choose whichever value seems more convenient.
Show each connection
For tees, reducers and crosses, identify every end separately. For elbows, include the specified angle and bend geometry. Show connection details, wall thickness requirements and any special machining. A photograph is useful for identification but is not a replacement for a dimensioned drawing.
Record changes without losing history
When revising an order, mark changed dimensions or quantities and state which revision replaces the previous one. Ask the supplier to confirm the effect on price and delivery before accepting the change. Keep one approved version attached to the final order so production, inspection and receiving refer to the same requirements.
Questions buyers often ask
Is a CAD file enough? Include a readable drawing with units and revision; different viewers may not show the same annotations. Can a replacement be made from a sample alone? Agree how the sample will be measured, which requirements still need confirmation and how the final drawing will be approved.