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A procurement-focused guide for specifying stainless steel welded pipe by governing standard, grade, NPS / DN, wall thickness or schedule, weld route, heat-treatment condition, inspection and documentation. Use the selector to define the starting requirement, then send the application details for a technical quotation and supplier capability review.
M03 · Grade specification / availability
The same stainless family can appear in different pipe standards with different manufacturing, heat-treatment, inspection and documentation rules. Grade selection should therefore follow service requirements and the governing standard, not a grade name alone.
A common starting family for general stainless process-piping applications where the service environment and design basis permit it.
Often evaluated where corrosion conditions are more demanding, including many chloride-containing services, but suitability remains application-specific.
May be selected for particular elevated-temperature or welded-service requirements when the governing specification and design basis call for a stabilized grade.
Use a duplex-specific pipe route such as ASTM A790 when the project requires ferritic / austenitic stainless pipe and its associated manufacturing and test requirements.
M04 · Technical data tables
Do not use a supplier inventory table as a substitute for the purchase specification. The exact numeric chemistry, mechanical properties, tolerances and test limits belong to the governing standard, project specification and approved material documents.
| Technical field | What the RFQ should state | Acceptance / review point |
|---|---|---|
| Governing standard | ASTM / ASME / EN / customer specification and required edition. | Confirm scope includes the requested welded pipe manufacturing route. |
| Grade / UNS | Exact designation belonging to the selected standard. | Verify chemistry and mechanical requirements on the MTC against that standard. |
| NPS / DN | Nominal pipe size or DN; add drawing-controlled OD where required. | NPS is a pipe-size designation, not automatically the actual outside diameter. |
| Wall thickness | Schedule designation such as 5S / 10S / 40S / 80S where applicable, or actual nominal wall. | Check dimensional standard and project tolerance requirements. |
| Length | Random, fixed, cut length or project-specific tolerance. | Confirm usable length, end allowance and packing limitations. |
| Weld / manufacture | Straight seam, electric-fusion welded, standard class or other route when specified. | Confirm the chosen standard permits and defines the requested manufacturing route. |
| Heat treatment | Condition required by the material specification or project document. | Do not assume annealed / unannealed status from appearance or grade alone. |
| Surface condition | Pickled, passivated or other project-controlled finish when required. | Agree surface acceptance, contamination controls and any additional treatment. |
| Ends | Plain, beveled or other drawing / piping-spec requirement. | Confirm angle / land / burr requirements when fabrication or welding depends on them. |
| Inspection & documents | NDE / hydrostatic or electric test, dimensional checks, PMI if required, MTC and traceability. | State the acceptance plan before purchase; do not add tests after shipment. |
M05 · Sizes, forms and finishes matrix
A useful welded pipe size request combines the nominal size system with wall, length, end preparation, surface condition and the governing manufacturing specification.
| Requirement | Preferred RFQ format | Avoid |
|---|---|---|
| Pipe size | NPS or DN, with actual OD only when a drawing or project spec controls it. | “100 mm pipe” without identifying DN / OD convention. |
| Wall | Schedule designation where applicable or nominal wall thickness with tolerance requirement. | Assuming the same schedule gives the same wall in every dimensional system. |
| Length | Fixed length, random length or cut list with tolerance. | Leaving length open when field fabrication depends on exact pieces. |
| Weld route | Per governing material standard; identify EFW / class when the specification requires it. | Calling every visible longitudinal seam “the same welded pipe.” |
| Condition | Heat-treated / unannealed only as permitted and required by the selected standard. | Choosing condition independently from the material specification. |
| Surface | State pickling / passivation / cleanliness requirement only when contractually needed. | Assuming a decorative finish is appropriate for piping service. |
| Ends | PE / BE or project-defined preparation with drawing if critical. | Leaving end prep unspecified when site welding or fit-up requires it. |
| Packing | Bundle, end protection, seaworthy / export or project packing requirements. | Treating packaging as irrelevant to surface and end protection. |
M06 · Selection / comparison matrix
The standards below are not interchangeable labels. They differ in material families, manufacturing routes, heat treatment, inspection and intended service. Use the project design basis to select the governing route.
Covers seamless, straight-seam welded and heavily cold-worked welded austenitic stainless steel pipe for high-temperature and general corrosive service.
Electric-fusion-welded austenitic chromium-nickel stainless steel pipe for high-temperature service and general applications, with class requirements affecting weld / radiography provisions.
Covers welded unannealed austenitic stainless tubular products for low and moderate temperatures and corrosive service where post-weld heat treatment is not necessary for corrosion resistance.
Covers seamless and straight-seam welded ferritic / austenitic stainless steel pipe for general corrosive service, with particular emphasis on resistance to stress-corrosion cracking.
M08 · Applications and limitations
“Stainless steel welded pipe” is a product form, not a complete design decision. The service fluid, temperature, pressure, corrosion environment, cleaning regime, piping code and joining method determine whether a particular grade and standard are suitable.
M10 · Standards and equivalence
The references below help identify common stainless welded-pipe routes and dimension terminology. The purchase order should name the required edition and grade. Cross-system “equivalence” must be reviewed against chemistry, mechanical properties, heat treatment, dimensions, tests and project acceptance criteria.
| Reference | Relevant scope | Procurement use |
|---|---|---|
| ASTM A312/A312M-25 | Seamless, welded and heavily cold-worked austenitic stainless steel pipe for high-temperature and general corrosive service. | Use when the project requires an A312 austenitic pipe route. |
| ASTM A358/A358M-24a | Electric-fusion-welded austenitic chromium-nickel stainless steel pipe for high-temperature service and general applications. | Specify the required class and any supplementary examination requirements. |
| ASTM A778/A778M-24a | Welded, unannealed austenitic stainless steel tubular products for defined low / moderate-temperature corrosive service. | Use only when the unannealed route is permitted by the project. |
| ASTM A790/A790M-24 | Seamless and welded ferritic / austenitic stainless steel pipe. | Common ASTM route for duplex stainless pipe. |
| ASTM A999/A999M-23 | General requirements applying to a group of alloy and stainless steel pipe specifications unless the individual product specification states otherwise. | Read with the applicable material specification; product-spec requirements prevail in a conflict. |
| ASME B36.19M-2018 | Standardization of dimensions for welded and seamless wrought stainless steel pipe. | Use for stainless pipe dimensional conventions where the project references B36.19M. |
Quote-ready worksheet
A complete enquiry reduces hidden assumptions and makes supplier comparisons more meaningful. Mark unknown fields for review rather than guessing.
| Field | What to state | Why it matters |
|---|---|---|
| Standard & grade | Material specification, edition, grade / UNS and any project supplements. | Defines the material and manufacturing acceptance basis. |
| Dimensions | NPS / DN, schedule or nominal wall, length and end preparation. | Defines fit-up, fabrication and quantity correctly. |
| Service context | Fluid / medium, temperature, pressure / design code and corrosion conditions where known. | Helps verify the proposed material route is technically relevant. |
| Manufacture / condition | Required welded route, class, heat treatment and surface condition where specified. | Prevents technically different products being compared as equivalents. |
| Inspection | Tests, NDE, dimensions, PMI if required, MTC, traceability and marking. | Makes buyer acceptance reviewable before shipment. |
| Commercial context | Quantity, destination, delivery date, Incoterm if known and contact details. | Allows a supplier to assess current sourcing and logistics feasibility. |
M11 · FAQ / direct answers
Short answers for common sourcing questions. Final material approval should still follow the project specification and engineering review.
It is stainless steel pipe produced by forming flat material into a tubular shape and joining the seam by a welding process defined by the applicable product specification. The exact manufacturing, heat-treatment and inspection route depends on standards such as ASTM A312, A358, A778 or A790.
There is no single standard for every welded stainless pipe application. A312 is a common austenitic process-pipe route; A358 covers EFW austenitic pipe; A778 covers an unannealed welded austenitic route for defined services; A790 covers ferritic / austenitic duplex pipe. Select the standard from the project piping specification or engineering basis.
Use NPS or DN together with schedule or nominal wall thickness, then add length, end preparation and any drawing-controlled OD / tolerance. Do not rely on a bare diameter number because pipe and tube use different sizing conventions.
No. 316L is often evaluated for more demanding corrosion environments, but “better” depends on the service medium, chloride level, temperature, cleaning regime, design code, fabrication and life-cycle requirements. Material selection should be application-specific.
Send the governing standard and edition, grade / UNS, NPS / DN, schedule or wall, length, ends, required manufacturing / heat-treatment route, inspection and document requirements, quantity, destination and requested delivery date. Attach the piping specification or drawing when it controls the purchase.
Product details
Use representative product, application and packing evidence to support a clear technical quotation.
Welded pipe resources
Review the parent material hub and related stainless product forms.
Open stainless steel hub →Use standards, comparison and engineering references to clarify the purchase specification.
Open technical resources →Send the known welded pipe specification fields and ask for supplier review.
M13 · Sources, author and review
This page uses official standards sources to explain specification logic. Stock range, current welded-pipe capability, mill approvals, certificates, inspection performance and delivery claims should only be published when attributable first-party evidence is available.
Austenitic stainless steel pipe scope including welded pipe.
View ASTM source →Electric-fusion-welded austenitic stainless steel pipe.
View ASTM source →Welded unannealed austenitic stainless tubular products.
View ASTM source →Stainless steel pipe dimensional standard.
View ASME source →Before indexing, replace this placeholder with an attributable supplier or mill range sheet showing the actual welded pipe standards, grades, size / wall combinations and manufacturing routes that can be offered.
Replace this placeholder with a real redacted MTC, inspection record, marking / traceability photo or other approved first-party quality evidence.
M14 · Form-specific RFQ
Send the fields you know. Supplier review should confirm current availability, manufacturing capability, inspection / documentation route, lead time and commercial terms for the actual enquiry.
Attach the piping specification, data sheet, drawing or inspection requirement when it controls the purchase.
