One dimension does not define a tube
State OD, wall, length, grade, standard, finish and end condition together. Nominal designations may not equal actual outside diameter.
Define the service first. Fluid, gas or pressure duties require the project specification, certified products and competent engineering; never assume a general industrial tube is suitable.
1. State OD and units
Give actual outside diameter in millimetres and the applicable tolerance. A single calliper reading may miss ovality.
For sleeves, clamps or bending, show mating dimensions, coating allowance and assembly method on the drawing.
2. Never assume wall thickness
One OD can have several walls. Specify the governing standard and tolerance; wall alone does not prove structural or pressure capacity.
Agree the inspection method, calibration, sampling and response to nonconformity before delivery.
3. Define length and allowance
Distinguish stock length, finished cut length and machining allowance. State tolerance, cut angle and deburring requirement.
Include saw kerf, end trimming, transport limits and safe handling in cutting optimisation.
4. Match ends to fabrication
Square, deburred, bevelled, threaded and capped ends are different delivery states. Welding bevel, root face and gap must follow the approved WPS.
Remove contamination before welding and address zinc-fume control and coating repair for galvanized material.
5. Specify surface protection
Black, oiled, primed and galvanized finishes are not interchangeable. Select the system for the environment and intended life.
Avoid trapped water; coordinate drain and vent details with structural behaviour and the coating process.
6. Require suitable traceability
Put certificate type, heat or batch identity and inspection scope in the order when needed. Match labels and documents before stock is dispersed.
Define how identity transfers to cut pieces and never treat undocumented stock as certified.
7. Reconcile quantity and weight
List pieces, length and total metres. Theoretical mass aids planning but may differ from actual mass due to tolerances and coating.
Prevent rolling, bundle movement and crushing during storage and lifting; apply the site handling plan.
8. Inspect before acceptance
Compare OD, wall, length, quantity, finish, ends and visible condition with the order and applicable standard.
Quarantine mixed, damaged or unidentified pieces. Confirm that the product and its documents suit the actual service.