Stainless Steel · Pipes · ASTM A312 / ASME SA312 TP304L
SS 304L Stainless Steel Pipes
In short: SS 304L pipe to ASTM A312 TP304L limits carbon to 0.030%, so welded joints stay resistant to intergranular corrosion without post-weld heat treatment. It is the usual choice for welded process, pharmaceutical and water-treatment piping.
- S30403
- UNS number
- 7.93
- density, g/cm³
- 3.1 / 3.2
- EN 10204 certificates
- 7
- SS 304L product forms
Why this combination
Why welded piping systems default to SS 304L
A piping system has hundreds of field and shop welds. In standard SS 304, each weld's heat-affected zone can precipitate chromium carbides and become a site for corrosion. SS 304L's low carbon prevents that, so fabricators avoid solution annealing after welding.
The trade-off is slightly lower strength, which is why many mills certify pipe as SS 304/304L: it meets 304's strength and SS 304L's carbon limit, and suits both drawings.
Specification
How to specify SS 304L pipes
NPS ⅛" to 48" and larger (DN 6 – DN 1200+), schedules 5S to XXS, single random, double random and cut lengths
- Specification
- ASTM A312 / ASME SA312 TP304L (seamless & welded); A358 EFW
- UNS
- S30403
- EN / W.Nr.
- 1.4307
- Grade marking
- TP304L, commonly dual TP304/TP304L
- Dimensions
- ASME B36.19M schedules 5S–80S
Sizes and weights
SS 304L pipes sizes, weighed at 7.93 g/cm³
Other sizes on request. For general pipes information, such as manufacturing routes and end finishes, see the pipes guide.
| NPS | OD mm | Sch 5S | Sch 10S | Sch 40S | Sch 80S |
|---|---|---|---|---|---|
| ½" | 21.34 | 1.65 / 0.81 | 2.11 / 1.01 | 2.77 / 1.28 | 3.73 / 1.64 |
| ¾" | 26.67 | 1.65 / 1.03 | 2.11 / 1.29 | 2.87 / 1.70 | 3.91 / 2.22 |
| 1" | 33.40 | 1.65 / 1.31 | 2.77 / 2.11 | 3.38 / 2.53 | 4.55 / 3.27 |
| 1¼" | 42.16 | 1.65 / 1.67 | 2.77 / 2.72 | 3.56 / 3.42 | 4.85 / 4.51 |
| 1½" | 48.26 | 1.65 / 1.92 | 2.77 / 3.14 | 3.68 / 4.09 | 5.08 / 5.46 |
| 2" | 60.33 | 1.65 / 2.41 | 2.77 / 3.97 | 3.91 / 5.50 | 5.54 / 7.56 |
| 2½" | 73.03 | 2.11 / 3.73 | 3.05 / 5.32 | 5.16 / 8.72 | 7.01 / 11.53 |
| 3" | 88.90 | 2.11 / 4.56 | 3.05 / 6.52 | 5.49 / 11.41 | 7.62 / 15.43 |
| 4" | 114.30 | 2.11 / 5.90 | 3.05 / 8.45 | 6.02 / 16.24 | 8.56 / 22.55 |
| 6" | 168.28 | 2.77 / 11.42 | 3.40 / 13.97 | 7.11 / 28.55 | 10.97 / 42.99 |
| 8" | 219.08 | 2.77 / 14.93 | 3.76 / 20.17 | 8.18 / 42.98 | 12.70 / 65.30 |
| 10" | 273.05 | 3.40 / 22.84 | 4.19 / 28.06 | 9.27 / 60.92 | 12.70 / 82.37 |
| 12" | 323.85 | 3.96 / 31.56 | 4.57 / 36.35 | 9.53 / 74.63 | 12.70 / 98.45 |
Chemistry
SS 304L composition
- UNS
- S30403
- EN / W.Nr.
- 1.4307 · X2CrNi18-9
- Density
- 7.93 g/cm³
- PREN
- 18 – 20
| Element | Limit, % | Why it matters |
|---|---|---|
| C | 0.030 max | |
| Mn | 2.00 max | |
| P | 0.045 max | |
| S | 0.030 max | |
| Si | 0.75 max | |
| Cr | 17.5 – 19.5 | |
| Ni | 8.0 – 12.0 | |
| N | 0.10 max |
Limits per ASTM A240; other product forms and specifications differ slightly. Your order's specification and edition govern.
Questions
About SS 304L pipes
Does SS 304L pipe need heat treatment after welding?
Normally no. Its low carbon content prevents sensitisation in the weld heat-affected zone during ordinary welding.
Is SS 304L pipe used above 425 °C?
Usually not for pressure parts. Low carbon reduces high-temperature strength, so SS 304H is specified in the creep range.
From enquiry to dispatch
How a SS 304L pipes order runs
- 01 EnquiryGrade, specification, size, quantity
- 02 ReviewChecked against your standard
- 03 InspectPMI, dimensions, TPI if required
- 04 CertifyEN 10204 3.1 / 3.2, heat traceable
- 05 ShipPacked and documented for the destination
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