254SMO Seamless Stainless Steel Pipe

UNS S31254 | 1.4547 | ASTM A312

Where chlorides push the standard 300-series grades to their limit, 254SMO (UNS S31254) is the austenitic answer: a molybdenum- and nitrogen-alloyed stainless steel developed for chloride-bearing media. The alloy balance raises resistance to pitting and crevice corrosion, the two mechanisms that most often decide equipment life once deposits form or liquid stops moving. 254SMO seamless stainless steel pipe therefore suits seawater distribution, desalination piping and aggressive chloride-bearing process lines, where the bulk analysis alone looks harmless but the local condition is not. Before fixing the grade, review water temperature, chlorination practice, flow velocity and stagnant pockets together. Xinzhe supplies this pipe to ASTM A312, with surface finish agreed at order. Every length is released against an EN 10204 3.1 mill test certificate, and 3.2 is available on request. Send the medium, chloride level, design temperature and pressure, and our engineers will confirm the selection.

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At a glance — 254SMO Pipe

Specification	ASTM A312 — the edition cited on the PO governs
Ordering basis	NPS × schedule, or OD × wall — stated on the order
Sourcing range	OD 6 – 1016 mm · wall 0.5 – 65 mm · length ≤ 18 m; each standard × OD × wall × length × condition confirmed in writing
Condition	Solution annealed; pickled & passivated, bright annealed or polished
Documents	EN 10204 3.1 MTC as standard (3.2 on request); hydrostatic or NDT electric test on every length

Sourcing capability, not a stock list — availability, MOQ and lead time are stated in the written quotation.

On this page

01Sizes 02Standards 03Chemistry 04Properties 05Dimensions 06Testing & MTC 07Applications 08Selection 09FAQ 10Related

Sizes, Wall Basis and Ordering

Two figures are kept apart here: the overall sourcing range — what we can supply ex-stock or source mill-direct — and the confirmed combination for your order (standard × size × wall × length × condition). The tables state the first; the written quotation fixes the second.

Supply combinations by size band

Size band, mm (NPS)	Wall range, mm	Supply route (ex-stock / mill-direct)	Order status
≤ 25	2.0 – 5.0	Ex-stock · standard walls	In stock · 3–7 days
> 25 – 114.3	2.5 – 12.0	Ex-stock; mill-direct above 6 mm wall	In stock / mill-direct
> 114.3 – 323.9	3.5 – 30.0	Mill-direct	Mill-direct · 25–35 days
> 323.9 – 610	6.0 – 50.0	Mill-direct	Mill-direct · 25–35 days
> 610 – 1016	8.0 – 65.0	Mill-direct	Mill-direct · 25–35 days

Stock items are marked In stock; everything else is mill-direct with a stated lead time. Schedule coverage follows the wall range shown for each band; non-standard walls are quoted individually. Above NPS 24 the tabulated dimensional bands no longer apply and the basis is agreed in writing.

Ordering options

Item	What can be ordered
Size	NPS and schedule, or actual OD × wall thickness
Outside diameter	6 – 1016 mm — to the ordered OD or to the NPS dimension
Wall thickness	0.5 – 65 mm — schedule wall or specified wall, stated on the order
Length	Random 5.8–7 m (single or double random), fixed up to 18 m
Ends	Plain, bevelled, or threaded with couplings
Surface	Pickled and passivated, or shot-blasted
Delivery condition	Solution annealed; hydrostatic or NDT route per specification

Sizes at the edge of a band are quoted after technical review. If your enquiry is written in NPS and schedule, the quotation restates it as OD × wall so our desk and your buying team are working from the same numbers.

Ordering Standards: A312 vs A213

A312 is the pipe specification and the one this page describes: the pipe is ordered by NPS and schedule and every length carries an integrity test. A213 is the tube specification, which uses OD and wall rather than NPS; it is quoted only when the line is dimensioned that way. Duplex pipe follows A790 and tube follows A789 — the grade is the same, the dimensional and test clauses are not.

Item	ASTM A312	ASTM A213
Scope	Seamless and welded pipe for pressure and corrosive service	Tube for heat transfer and pressure parts
Ordering basis	NPS × schedule, or OD × wall	OD × wall × length, no NPS
Wall basis	Nominal wall with the standard tolerances	Minimum or average wall, stated on the order
Testing	Integrity test per length; NDT level as agreed	Integrity test per length, plus flattening or flare
Typical use	Process and transfer lines, piping spools	Heat exchangers, condensers, boilers

A312 and A790 are the two pipe specifications that matter for this grade family; A213 and A789 cover the tube form. Nickel alloys follow the B-series pipe specifications (B619, B725, B165 and the matching part of each alloy's standard) — state the exact specification and edition.

Chemical Composition (254SMO Heat-Analysis Limits)

Chemical composition, % by weight:

C	Cr	Ni	Mo	N	Cu	S	P	Si	Mn	Fe
≤ 0.020	19.50–20.50	17.50–18.50	6.00–6.50	0.18–0.25	0.50–1.00	≤ 0.010	≤ 0.030	≤ 0.80	≤ 1.00	Bal

Values are the heat-analysis limits of the specification named above. Product analysis on the finished tube or pipe may differ within the tolerances the standard permits, and the actual heat analysis is printed on the mill test certificate.

Mechanical Properties and Physical Data

Mechanical properties:

Tensile Strength, min.		Yield Strength, min.		Elongation, min.	Hardness, max.
ksi	MPa	ksi	MPa	%	Brinell HBW	Rockwell
98 (t ≤ 5 mm) 95 (t > 5 mm)	675 (t ≤ 5 mm) 655 (t > 5 mm)	45	310	35	220	96 HRBW

Typical physical properties:

Property	Value	Unit
Density	8.1	g/cm³
Modulus of elasticity	200	GPa
Thermal conductivity (20 °C)	13.0	W/(m·K)
Specific heat	500	J/(kg·K)
Melting range	1320–1390	°C

Tensile and yield values are specification minima at room temperature; hardness and grain size are reported when the purchase order asks for them. Design values at service temperature must be taken from the applicable code, not from this table.

Permissible Variations in Dimensions (A312)

Dimensional acceptance follows A999/A999M for A312 pipe and the corresponding tables of A790 for duplex. The bands below are representative; the edition cited on the purchase order governs, and measured values are recorded on the mill test certificate.

Outside diameter

NPS	Permissible variation
1/8 – 1 1/2	+ 0.4 / − 0.8 mm
2 – 4	+ 0.4 / − 0.8 mm
5 – 8	+ 0.8 / − 0.8 mm
10 – 18	+ 1.6 / − 0.8 mm
20 – 24	+ 2.4 / − 0.8 mm
> 24 – 40	Agreed in writing

The variation applies to the individual measurement. For bored pipe the wall is measured at the ends as well as mid-length.

Wall thickness

Condition	Permissible variation
Seamless, t/D ≤ 5 %	+ 20 % / − 12.5 % of nominal wall
Seamless, t/D > 5 %	+ 22.5 % / − 12.5 % of nominal wall
Minimum wall ordered	No point below the ordered minimum

Where the design uses a minimum wall, the order must say so; a nominal-wall order does not guarantee the minimum the calculation assumed.

Random lengths 5.8–7 m single random, 11–13 m double random, unless a fixed length is ordered. End squareness and bevel angle are inspected before packing.

Inspection, Testing and Mill Test Certificates

Three groups of evidence are separated here, because only the first is inside the base price. Anything in the second and third groups has to be written on the purchase order — it cannot be added after the mill test certificate has been issued.

Group	Content	How it is triggered
1 — Included	Chemical analysis, tensile test, flattening or bend test, hydrostatic or nondestructive electric test, dimensional check, EN 10204 3.1 certificate	Standard supply; no extra instruction needed
2 — Written on the PO	Ultrasonic or eddy-current testing to a stated acceptance level, PMI on each heat, intergranular corrosion test, grain size, hardness survey, 3.2 certificate	Must appear on the purchase order; priced per order
3 — Third party	TPI witness (SGS, BV, TÜV, Lloyd's), destructive sampling, third-party laboratory, packing inspection, pre-shipment photographs	Arranged per order; extends the lead time

The test route is not interchangeable after the fact: if the certificate has to show ultrasonic testing, say so on the enquiry, because a hydrostatic-only pipe cannot be re-certified as ultrasonically tested.

What the mill test certificate records

Heat number	The melt the item came from, traceable to the raw-material certificate
Grade and specification	Grade designation plus the standard and edition the order cites
Chemical analysis	Actual values for each element, not the range
Mechanical results	Tensile, yield, elongation and hardness as tested
Test route	Hydrostatic or nondestructive electric test, plus any agreed NDT with the method reference
Heat treatment	Solution-annealing temperature range and cooling method
Dimensions	Ordered OD, wall and length, with the measured values on request

254SMO Pipe Applications and Points to Confirm

Each application below names the duty the grade is normally chosen for, and what should be settled before the order is placed — the third column decides whether this grade is the right one:

Industry	Typical duty
Marine & offshore	salt-laden marine duty
Desalination	high-chloride seawater duty
Chemical processing	aggressive reaction and transfer duty
Pulp & paper	cooking liquor and bleaching duty
Oil & gas	wellhead, manifold and topside duty
Water treatment	water and wastewater duty

Points to confirm before ordering

Medium, concentration and chloride content — the figures that decide whether this grade holds
Design temperature and pressure, including upset and cleaning cycles
Whether the joint is welded, and the post-weld condition required
Inspection and document scope: NDT level, PMI, third-party witness

Send the medium, concentration, temperature, pressure and chloride level, and we will confirm the grade — or propose the next one up if the margin is narrow.

Grade Selection: 254SMO vs TP904L

Property	254SMO	TP904L
PREN, typical	43	34
Molybdenum	6.00–6.50	4.00–5.00
Yield strength, min.	≥ 300 MPa	≥ 220 MPa
Service temperature	≈ 400 °C	≈ 400 °C
Choose when	General corrosion service, welded assemblies, cost-sensitive projects	Lower alloy content is enough for the duty

PREN is indicative only and is calculated from the composition ranges above — it is not an acceptance value. Where the duty sits between two grades, the deciding factors are usually chloride content, temperature and whether the joint is welded.

Frequently Asked Questions

What sizes can be supplied in 254SMO pipe?

The overall sourcing range is OD 6 – 1016 mm, wall 0.5 – 65 mm, length 18 m. The band table shows the wall range normally held or supplied for each OD band; the exact combination of standard, OD, wall, length and manufacturing condition is confirmed in the quotation. Sizes at the edge of a band are quoted after technical review.

Is this page a stock list?

In part. Stocked sizes are marked In stock and ship in 3–7 days; everything else is mill-direct with a 25–35 day lead time, confirmed per item in the quote.

Is 254SMO pipe ordered by NPS or by outside diameter?

Either, but it must be clear. NPS with schedule is the usual purchase form for process piping; actual OD × wall is used when the line is dimensioned that way. The quotation restates the order in both notations so our desk and your buying team are working from the same numbers.

Which specification applies — A312 or A213?

ASTM A312 is the primary specification for this pipe and the one the page describes. ASTM A213 is the adjacent specification; whether it applies depends on the ordered form, the test regime and the design code. State the standard and edition on the enquiry and the certificate will cite the same one.

Which tests and documents are included?

Mandatory: one integrity test per length (hydrostatic or nondestructive electric), tensile test per lot, dimensional check and an EN 10204 3.1 mill test certificate. Optional and only when written on the order: ultrasonic or eddy-current testing to a stated level, PMI, intergranular corrosion test, grain size, third-party witness and 3.2 certification.

How does 254SMO compare with TP904L?

TP904L is the usual comparison grade. 254SMO carries PREN of about 43 against 34 for TP904L, with a minimum yield of 300 MPa. The change is normally made when the duty — chloride level, temperature or pressure — leaves TP904L without margin over the design life.

Request a 254SMO Pipe Quotation

Send: specification and edition, OD or NPS, wall and wall basis, length, quantity, surface finish, inspection scope and documents, and destination port. The quotation will restate the confirmed size combination, delivery condition, documents included and lead time for 254SMO Pipe.

Request a 254SMO Pipe quotation

Related Product Forms and Grades

Other forms and neighbouring grades, each with its own specification — confirm the applicable standard on every order:

254SMO seamless tube — UNS S31254 · W-Nr 1.4547
TP904L seamless pipe — TP904L — the grade normally compared with 254SMO on this duty
Incoloy 028 seamless pipe — UNS N08028 · W-Nr 1.4563
Alloy 31 seamless tube — UNS N08031 · W-Nr 1.4562
Contact the sales team — Sizes outside the range, non-standard lengths and third-party inspection

Technical data compiled from the ASTM/ASME specification tables cited above and from published mill data. Page reviewed by the Xinzhe technical team, 09–11-2026. All values must be confirmed against the edition current at the time of order and against the heat certificate.