Decode the enquiry
NPS is a nominal size designation; it is not generally the measured outside diameter. SCH, STD and a measured wall thickness are not interchangeable without the relevant table. Confirm units whenever an enquiry mixes inches, millimetres and schedule designations.
Manufacture and grade
Hot-finished and cold-finished routes have different processing and dimensional implications. ASTM A106, ASTM A53 and API 5L cover different scopes. An API X grade does not define every pressure, temperature, corrosion or welding requirement for a piping system.
Pressure and acceptance
Pressure rating depends on design code, diameter, minimum wall, allowable stress, temperature, allowances and joints. Request the actual certificate, ordered tests and end finish. Hydrostatic or nondestructive examination requirements must follow the applicable product and project rules, not a generic online pressure table.
Information to record
- Exact product standard and edition; approved drawing or specification revision.
- Grade, dimensions, final condition and heat-to-piece traceability.
- Acceptance test, inspection document and responsible approving party.
Frequently asked questions
Can I calculate safe pressure from schedule alone?
No. The design code, actual pipe size, grade, temperature and allowances are also required.
Sources and reference scope
- Procurement and editorial guidance — Cross-checked against product terminology and the cited material rules
Guidance describes checks to request. It is not a claim of available stock, certificates or completed project engineering. - 钢材产品简介 — Slides 3, 5–6, 15–19
Product forms, units and grade vocabulary; not proof of current stock or class certification.