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304 is an austenitic stainless steel. The short version: it's roughly 18% chromium, 8% nickel, balance iron with small amounts of carbon, manganese, and silicon. The chromium forms a passive oxide layer on the surface that stops rust. The nickel keeps the structure austenitic, which gives it ductility and weldability.
The standard grade everybody knows is ASTM A312 TP304. UNS number is S30400. In Europe, the same material shows up as EN 10216-5 grade 1.4301. In China, the national standard equivalent is GB/T 14976 06Cr19Ni10 (formerly 0Cr18Ni9).
The chemical composition across these standards is effectively identical. But "effectively identical" and "interchangeable in your customer's receiving inspection" are two different things. We'll get to that.
304 across standards
| Standard | Grade | Application |
|---|---|---|
| ASTM A312 | TP304 | General process pipe, pressure service |
| ASTM A312 | TP304L | Low-carbon variant, better for welding |
| ASTM A312 | TP304H | High-carbon variant, elevated temp service |
| EN 10216-5 | 1.4301 | Pressure equipment (EU market) |
| EN 10216-5 | 1.4307 | Low-carbon (304L equivalent) |
| GB/T 14976 | 06Cr19Ni10 | Chinese national standard |
Typical mechanical properties (ASTM A312 TP304, annealed):
Tensile strength: ≥ 515 MPa (75 ksi)
Yield strength (0.2% offset): ≥ 205 MPa (30 ksi)
Elongation: ≥ 35% in 50mm
Hardness: ≤ 90 HRB
Where 304 Works - and Where It Doesn't
One of the most useful things a procurement person can know is when to stop buying 304.
Good applications for 304 pipe
- Potable water lines (municipal and industrial)
- Food and beverage processing (dairy, brewing, soft drinks)
- Architectural handrails and structural tubing
- Low-pressure steam condensate return lines
- Pharmaceutical clean utilities (WFI, clean steam - though 316L is more common)
- General chemical transfer where the fluid chemistry is well understood and non-aggressive
- Heat exchanger tubing in moderate service (below 400°C, non-corrosive fluids)
Where 304 fails - and what to use instead
Chloride environments. This is the big one. 304 has poor resistance to chloride stress corrosion cracking (SCC). Above 60°C, even low chloride levels can crack 304. For seawater, brackish water, or any process fluid with chlorides above 200 ppm, move to 316L or duplex (S32205/S32750).
High-temperature sulfur environments. In refinery service with H2S present, 304 can suffer sulfidation above about 400°C. Refineries typically use stabilized grades (321/347) or move to higher alloys.
Strong reducing acids. Hydrochloric acid will eat 304. Sulfuric acid at certain concentrations and temperatures will too. These applications need higher nickel alloys - Hastelloy C2000, Monel 400, or in some cases super-duplex.
Sour service (NACE MR0175). 304 in the annealed condition is generally acceptable under NACE MR0175/ISO 15156 for H2S service, but only within hardness limits (≤ 22 HRC). If the pipe has been cold worked (common in some forming operations), hardness can rise above the limit and the pipe becomes unsuitable.
What Drives 304 Pipe Prices
304 stainless steel pipe pricing follows raw material inputs more directly than most people realize.
The alloy surcharge is the biggest variable. 304 contains roughly 8% nickel and 18% chromium. When nickel moves on the LME (London Metal Exchange), 304 pipe prices follow within weeks.
In 2022, nickel spiked above $100,000/tonne briefly during the LME short-squeeze event. 304 pipe prices doubled almost overnight for spot buyers. Contract buyers with formula-based pricing had some protection, but not much. Chromium prices matter too, but nickel is the main driver because it's the more expensive component and its price is more volatile.
Other factors that hit 304 pipe pricing:
Energy costs for the mill. Stainless steel melting and hot rolling are energy-intensive. European mills got hammered on this in 2022-2023.
Shipping. A 40-foot container from Shanghai to Rotterdam or Dammam costs anywhere from 1,500to1,500to15,000 depending on the shipping cycle. That can swing the landed cost of pipe by 5-15%.
Schedule and size. Thin-wall, small-diameter pipe has higher per-ton conversion costs. Odd schedules cost more because the mill may need to set up a dedicated run.
Certification adders. PED-certified 304 pipe typically carries a 5-10% premium over standard ASTM material from the same mill. Saudi Aramco-approved sources command additional premium.
Quantity. Below about 5 tonnes of a single size/schedule, you're paying distribution markup, not mill pricing.
Frequently Asked Questions
What's the difference between 304 and 304L stainless steel pipe?
304L contains maximum 0.03% carbon versus 304's maximum 0.08%. The lower carbon reduces the risk of intergranular corrosion (sensitization) after welding. For welded pipe that won't be solution-annealed after welding, 304L is the safer choice. Mechanically, 304L has slightly lower minimum tensile and yield strength in some specifications, though in practice modern production usually exceeds both.
Is 304 stainless steel pipe suitable for seawater?
No. 304 corrodes in seawater due to chloride attack. For seawater service, use 316L as a minimum, or duplex stainless steel (S32205) for better performance. Even 316L will eventually pit in stagnant seawater. For critical seawater piping, super-duplex (S32750) or higher alloys are common.
Can 304 pipe be used for drinking water?
Yes, 304 is widely used in potable water systems. It doesn't leach harmful substances and meets drinking water contact standards in most countries (NSF/ANSI 61 in the US, DWD in Europe, AS/NZS 4020 in Australia). The exception is water with elevated chloride levels, where 316L should be considered.
What's a normal price range for 304 stainless steel pipe?
As of mid-2026, standard-schedule 304 seamless pipe from an Asian mill ranges from roughly 3,500 to 5,500 per tonne FOB, depending on size, schedule, and quantity. PED-certified material adds 5-10%.
How do I verify that the pipe is actually 304 and not a lower grade?
A handheld XRF analyzer gives a quick reading of the main alloying elements (Cr, Ni, Mn, Mo). If the readings fall within 304's expected range (roughly 18% Cr, 8% Ni), the material is likely 304. For definitive verification, send a sample to a lab for optical emission spectroscopy (OES) with carbon and sulfur analysis. XRF cannot reliably measure carbon, so it can't distinguish 304 from 304L.
Does 304 pipe need post-weld heat treatment?
Generally no for most applications, especially if using 304L filler metal. For thick sections (above roughly 12mm wall) or where the service environment is aggressive, solution annealing after welding may be recommended. For 304 (non-L) welded without post-weld treatment, the heat-affected zone can be susceptible to intergranular corrosion in certain environments. This is why 304L was developed.
