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ASTM & AISI
Steel Grades
A world-class technical reference for EPC engineers, materials engineers, procurement heads, TPI inspection agencies, and global project buyers navigating the ASTM and AISI steel grade systems — covering the structure of both standards bodies, the distinction between ASTM product standards and AISI composition grades, the critical cross-reference between ASTM, AISI, UNS, EN, DIN, and JIS grade designations, and the complete engineering framework for specifying carbon, alloy, and stainless steel products for process piping, pressure vessels, structural, fastener, and hydraulic applications worldwide.
How the Two Systems
Work Together
ASTM & AISI Steel Grades are complementary, not competing, steel classification systems. Understanding the distinction — ASTM defines product requirements; AISI defines chemical composition — is the foundation for correct steel specification on any EPC, hydraulic, or industrial project.
1.1 — ASTM & AISI Steel Grades International: Product Standards
ASTM International (formerly the American Society for Testing and Materials) publishes product standards that define the complete requirements for a manufactured steel product — not just the chemical composition, but the manufacturing process, heat treatment, dimensional tolerances, mechanical property minimums, required testing, inspection, marking, and documentation. An ASTM standard specifies everything needed to order, receive, and qualify a steel product for a stated purpose.
ASTM standards are organised by product form and application: A-series (ferrous metals — steel, cast iron, stainless); B-series (non-ferrous metals — copper, aluminium, nickel alloys); C-series (cement, concrete, ceramic); and so on. Within the A-series, products are further organised by product form: pipe (A53, A106, A335), tube (A213, A269), plate (A516, A537), bar (A276, A479), forgings (A105, A182), castings (A216, A351), fittings (A234, A403), flanges (A182), and fasteners (A193, A307, A325). Each standard lists: the permitted steel grades (e.g., A106 covers Grades A, B, and C); the chemical composition of each grade; the required heat treatment (hot-finished, cold-drawn, normalised, quenched and tempered); the minimum mechanical properties (yield, UTS, elongation, CVN impact); the required nondestructive examination; and the documentation requirements (mill test report, EN 10204 equivalent).
The critical engineering rule: always specify the ASTM product standard AND the grade — “A106 Grade B” is a complete specification; “A106” alone (no grade) or “carbon steel pipe” alone are incomplete and can result in substandard or incorrect material being supplied.
1.2 — ASTM & AISI Steel Grades: Composition Grade Designation System
The American Iron and Steel Institute (AISI) numbering system defines steel chemical composition categories — it tells you what the steel is made of, not what product form or properties it provides. The AISI system uses a four-digit number (occasionally five digits for some stainless grades): the first one or two digits identify the steel category (alloy type); the last two or three digits indicate the nominal carbon content in hundredths of a percent.
1.3 — The Unified Numbering System (UNS)
The Unified Numbering System (UNS), maintained jointly by ASTM and SAE, provides a single cross-reference number that links the AISI grade designation to all applicable product standards across all standards organisations — ASTM, SAE, AWS, and foreign equivalents. A UNS number (format: letter prefix + five digits, e.g., G10180 for AISI 1018 carbon steel; S31600 for AISI 316 stainless) uniquely identifies a specific alloy composition regardless of the product form or governing standard. The UNS system is the bridge between the AISI composition designation and the ASTM product standard — when a procurement document specifies “ASTM A276 UNS S31600” the UNS number confirms that the product is 316 stainless steel (not 316L, not 317) in bar form per A276.
1.4 — AISI vs ASTM: How They Complement Each Other
| What You Know | ASTM Gives You | AISI Gives You | Complete Specification Requires |
|---|---|---|---|
| Ordering seamless pipe for steam service | A106 Gr.B — pipe dimensions, heat treatment, mechanical properties, NDE, marking | Composition ref only (not a pipe standard) | ASTM A106 Grade B — fully specified |
| Ordering bar for a machined shaft | A108 (cold-drawn bar) — tolerances, finishes | 1045 — C:0.43–0.50%; Mn:0.60–0.90% | ASTM A108 Grade 1045 (or “1045 cold-drawn bar per A108”) |
| Ordering SS 316L forged fittings | A182 — forging standard; flanges & fittings | 316L = C≤0.03%, 16–18% Cr, 10–14% Ni, 2–3% Mo | ASTM A182 Grade F316L (or F316L per UNS S31603) |
| Ordering alloy steel tube for heat exchanger | A213 — seamless ferritic / austenitic alloy tube | 4140 = 0.38–0.43% C, 0.8–1.1% Cr, 0.15–0.25% Mo | ASTM A213 Grade T22 (not 4140 — A213 uses “T” grades) |
| Ordering SS plate for pressure vessel | A240 — plate, sheet, strip | 304L = C≤0.03%, 18–20% Cr, 8–12% Ni | ASTM A240 Grade 304L (or A240/A240M Type 304L) |
1.5 — The P-Number System (ASME IX Welding)
P-No. 3 = Low-alloy steels ½Mo, ½Cr-½Mo, ¾Cr-½Mo (A335 P1, P2; A213 T2)
P-No. 4 = Low-alloy steels 1Cr-½Mo, 1¼Cr-½Mo (A335 P11/P12; A182 F11/F12)
P-No. 5A = Low-alloy steels 2¼Cr-1Mo, 3Cr-1Mo (A335 P22/P21; A182 F22)
P-No. 5B = Low-alloy steels 5Cr-½Mo, 7Cr-½Mo, 9Cr-1Mo (A335 P5/P9; A182 F5/F9)
P-No. 5C = 9Cr-1Mo-V (P91) — must be qualified separately from other P5 groups (A335 P91; A182 F91)
P-No. 6 = Martensitic stainless steels (A276 Type 410, 420)
P-No. 7 = Ferritic stainless steels (A276 Type 405, 430)
P-No. 8 = Austenitic stainless steels (A312 TP304, TP316, TP321; A182 F304, F316) — Groups 1, 2, 3
P-No. 10H = Duplex stainless steels (A790 S31803/S32205 Duplex; S32750 Super Duplex)
P-No. 45 = Nickel alloys (Inconel 625, Hastelloy C276, Incoloy 825) — multiple sub-groups
A105N = P-No. 1, Group 1; A106 Gr.B = P-No. 1, Group 1 — same P-Number and Group
One WPS qualified for P-No. 1, Gr. 1 to P-No. 1, Gr. 1 per ASME IX covers this combination
→ No dissimilar metal weld qualification required; the pre-existing P-No.1 WPS is adequate
Submit your grade, product form, dimensions, and quantity for a documented RFQ within 24 hours.
Cross-Reference
& Equivalent Grades
The most common practical need in international EPC procurement is mapping an ASTM grade specified in the US-coded project to the EN/DIN/JIS equivalent — or vice versa. These cross-reference tables cover the most frequently encountered grades in process piping, pressure vessels, and hydraulic applications. All supported grades available from RR Hydraulic.
Submit ASTM grade, product form, dimensions, and quantity to sales@rrhydraulics.com for a certified offer.
2.1 — Carbon and Low-Alloy Steel: ASTM–EN–DIN Cross-Reference
| ASTM Standard + Grade | AISI Grade | UNS | EN / DIN Equivalent | P-No. | Typical Application |
|---|---|---|---|---|---|
| A106 Gr.B (pipe) | — | K03006 | EN 10216-1 P265GH / DIN St35.8 | 1 | High-temp seamless carbon steel pipe; process piping |
| A53 Gr.B (pipe) | — | K03005 | EN 10255 S195T / DIN St37 | 1 | General-purpose pipe; low-pressure utility |
| A105N (forgings) | — | K03504 | EN 10250-2 C22E / DIN 1.0402 | 1 | Forged flanges, fittings, olets; process piping |
| A234 WPB (BW fittings) | — | K03006 | EN 10253-2 P235G1TH | 1 | Butt-weld fittings; elbows, tees, reducers |
| A335 P11 (pipe) | — | K11597 | EN 10216-2 13CrMo4-5 / DIN 1.7335 | 4 | High-temp alloy pipe; 1¼Cr-½Mo; steam service |
| A335 P22 (pipe) | — | K21590 | EN 10216-2 10CrMo9-10 / DIN 1.7380 | 5A | Very high-temp alloy pipe; 2¼Cr-1Mo; reformer |
| A335 P91 (pipe) | — | K90901 | EN 10216-2 X10CrMoVNb9-1 / DIN 1.4903 | 5C | USC steam piping; 9Cr-1Mo-V; power generation |
| A516 Gr.70 (pressure vessel plate) | — | K02700 | EN 10028-2 P355GH / DIN 1.0473 | 1 | Pressure vessel plate; moderate temperature |
| A333 Gr.6 (low-temp pipe) | — | K03008 | EN 10216-4 P215NL / DIN TStE285 | 1 | Low-temp seamless pipe; LPG; −46°C service |
| A193 B7 (stud bolts) | 4140 / 4142 | G41400 | EN ISO 898-1 Property Class 8.8 / DIN 42CrMo4 | 4 | High-strength Cr-Mo stud bolts; ASME Class 150–2500 |
2.2 — Stainless Steel: ASTM–AISI–EN–DIN Cross-Reference
| ASTM Standard + Grade | AISI Grade | UNS | EN Number / DIN | P-No. | Typical Application |
|---|---|---|---|---|---|
| A312 TP304L (pipe) | 304L | S30403 | EN 1.4307 / X2CrNi18-9 | 8 Gr.1 | General chemical; food; cryogenic piping |
| A312 TP316L (pipe) | 316L | S31603 | EN 1.4404 / X2CrNiMo17-12-2 | 8 Gr.1 | Corrosive chemical; offshore; marine process piping |
| A182 F316L (forgings) | 316L | S31603 | EN 1.4404 forged | 8 Gr.1 | Forged flanges, fittings, olets — SS 316L |
| A276 316L (bar) | 316L | S31603 | EN 1.4404 bar (EN 10272) | 8 Gr.1 | Machined components; shafts; valve bodies |
| A312 TP321 (pipe) | 321 | S32100 | EN 1.4541 / X6CrNiTi18-10 | 8 Gr.2 | High-temp SS; Ti-stabilised; exhaust piping |
| A312 TP347 (pipe) | 347 | S34700 | EN 1.4550 / X6CrNiNb18-10 | 8 Gr.2 | High-temp SS; Nb-stabilised; nuclear steam |
| A790 S31803 (pipe) | — | S31803 | EN 1.4462 / X2CrNiMoN22-5-3 | 10H | Duplex 2205; offshore sour; seawater |
| A790 S32750 (pipe) | — | S32750 | EN 1.4410 / X2CrNiMoN25-7-4 | 10H | Super Duplex 2507; extreme chloride; subsea |
| A276 Type 410 (bar) | 410 | S41000 | EN 1.4006 / X12Cr13 | 6 | Martensitic SS; valve stems; fasteners |
| A276 Type 430 (bar) | 430 | S43000 | EN 1.4016 / X6Cr17 | 7 | Ferritic SS; architectural; non-pressure applications |
2.3 — AISI Carbon and Alloy Steel Bar Grades
| AISI Grade | UNS | C (%) | Key Alloying | UTS (N+T, MPa) | Yield (N+T, MPa) | Typical EPC Application |
|---|---|---|---|---|---|---|
| 1018 | G10180 | 0.15–0.20 | Plain carbon (low) | 400 | 220 | Cold-drawn bar; low-stress machined parts; shafts |
| 1045 | G10450 | 0.43–0.50 | Plain carbon (medium) | 570 | 310 | Medium-strength shafts; gear blanks; pins; couplings |
| 4130 | G41300 | 0.28–0.33 | 0.8–1.1% Cr; 0.15–0.25% Mo | 670 (ann) | 435 | Structural; aircraft; hydraulic cylinders; tooling |
| 4140 | G41400 | 0.38–0.43 | 0.8–1.1% Cr; 0.15–0.25% Mo | 655 (ann) | 415 | High-strength shafts; gears; ASTM A193 B7 bolting |
| 4340 | G43400 | 0.38–0.43 | 1.65–2.0% Ni; 0.7–0.9% Cr; 0.2–0.3% Mo | 745 (ann) | 470 | Very high-strength structural; aircraft; large diameter shafts |
| 8620 | G86200 | 0.18–0.23 | 0.4–0.7% Ni; 0.4–0.6% Cr; 0.15–0.25% Mo | 520 | 385 | Case-hardening; gears; camshafts; bearing races |
| D2 (tool steel) | T30402 | 1.40–1.60 | 11–13% Cr; 0.7–1.2% Mo; 0.2–0.5% V | — | — | Cold work die steel; punching tools; forming dies |
| H13 (tool steel) | T20813 | 0.32–0.45 | 4.75–5.5% Cr; 1.1–1.75% Mo; 0.8–1.2% V | — | — | Hot work die steel; extrusion tooling; die casting dies |
2.4 — Key ASTM Product Standards for EPC Piping and Pressure Equipment
A106 — Seamless Carbon Steel Pipe
The most important ASTM carbon steel pipe standard for EPC process piping. Three grades: A (C ≤ 0.25%), B (C ≤ 0.30%), C (C ≤ 0.35%). Grade B is the universal standard for high-temperature seamless carbon steel process piping in Oil & Gas, Power, and Chemical EPC projects — used for all ASME B31.3 carbon steel piping up to 427°C. Normalising is required for wall thickness above 19 mm (¾”). Hot finishing is acceptable for standard thicknesses. The most commonly specified pipe material in EPC project piping material requisitions — specifying “A106 Gr.B” on every carbon steel seamless piping MR line item is correct EPC procurement practice.
A312 — Seamless and Welded SS Pipe
The primary ASTM standard for austenitic stainless steel seamless and welded pipe. Covers all common SS grades: TP304, TP304L, TP316, TP316L, TP321, TP347, TP317L, and Duplex/Super Duplex grades. Solution-annealed condition standard (mandatory for TP316L to maintain NACE compliance and sensitisation resistance). “TP” prefix (Type) distinguishes the grade within A312. Always specify A312 with the full grade designation: “ASTM A312 TP316L” — never just “SS 316L pipe” without the ASTM standard, as non-ASTM pipe does not carry the required mechanical property and testing certification for coded process piping.
A182 — Forged Alloy and SS Flanges and Fittings
The comprehensive ASTM forging standard covering all alloy and stainless steel flanges, fittings, and valves for high-temperature service. Grade designation: “F” prefix (Forged). F304, F316, F316L, F321, F347 for SS; F11, F22, F91 for Cr-Mo alloy steels; F51 (Duplex 2205), F53 (Super Duplex 2507). A182 is the single most important ASTM forging standard in EPC piping procurement — it covers all the alloy and SS flange, fitting, and valve body materials for coded process piping. Always cite A182 with the specific grade: “ASTM A182 F316L” for every SS forged flange and fitting in the piping MR.
A193 — Alloy Steel and SS Bolting for High-Temperature
Stud bolts and threaded fasteners for high-temperature pressure vessel and piping flange connections. Grade B7 (4140/4142 Cr-Mo alloy steel, quenched and tempered): the standard flange stud bolt for ASME Class 150# through 2500# carbon steel process piping at temperatures up to 427°C. Grade B7M: reduced hardness variant (≤ 35 HRC) for NACE sour service environments. Grade B8M (316 SS) for stainless and alloy piping flanges in corrosive service. Grade B16 (CrMoV alloy) for high-temperature steam flanges above 427°C. A194 Grade 2H heavy hex nuts are the standard companion nut for B7 stud bolts.
A216 / A351 — Carbon and SS Steel Castings
A216: Steel Castings, Carbon, Suitable for Fusion Welding, for High-Temperature Service — Grades WCA, WCB, WCC for carbon steel valves, pump bodies, and vessel nozzles. WCB is the standard grade for carbon steel cast valve bodies in ASME Class 150# and 300# process piping. A351: Steel Castings, Austenitic, for High-Temperature Service — Grades CF8 (304), CF8M (316), CF3M (316L), CD4MCu (Duplex) for stainless steel valves and pump casings. A351 CF8M (316 SS) is the standard for stainless steel cast gate, globe, and check valves in ASME B31.3 corrosive service piping.
A516 — Pressure Vessel Plate for Moderate / Low Temperature
Carbon steel plate for pressure vessels, heat exchanger shells, and storage tanks at moderate and low temperatures. Four grades: 55, 60, 65, 70 (yield strength in ksi). Grade 70 (UTS 485–620 MPa; yield ≥ 260 MPa) is the most widely used for process vessel shells, tower vessels, and storage tanks in EPC Oil & Gas and Chemical projects. Normalised for wall thickness above 38 mm. For low-temperature service below −29°C: A516 requires Charpy impact testing (ASTM A20 supplementary requirement S5) to confirm adequate toughness at the design minimum temperature — verify the minimum design temperature against A516 Gr.70 impact test exemption curves in ASME VIII Div.1 Fig. UCS-66.
A213 — Seamless Ferritic and Austenitic Alloy Tube
Seamless alloy steel and stainless steel tube for heat exchanger and steam generator service. “T” prefix grades for ferritic alloy (T2, T11, T22, T91) and TP prefix for austenitic SS (TP304, TP316L, TP321). A213 T22 (2¼Cr-1Mo) is the standard for high-temperature heat exchanger tube service in refinery and petrochemical plants up to 649°C. A213 TP316L for corrosive service heat exchanger tube (shell and tube, plate type). A213 distinguishes heat exchanger tube (A213) from structural tube (A519) and hydraulic tube (A519 / A513) — specify A213 for pressure-service heat exchanger tube; non-A213 tube does not carry the required hydrostatic test or NDE that heat exchanger tube must provide.
A790 — SS Duplex and Super Duplex Pipe
Seamless and welded stainless steel Duplex and Super Duplex pipe. Grades: S31803 (Duplex 2205 — 22% Cr, 5% Ni, 3% Mo); S32205 (upgraded 2205 with tighter composition limits); S32750 (Super Duplex 2507 — 25% Cr, 7% Ni, 4% Mo); S32760 (Zeron 100 Super Duplex). Solution-annealed condition. Ferrite content verification per ASTM E562 mandatory for EPC and offshore Duplex pipe supply. A790 is the primary pipe standard for Duplex and Super Duplex process piping on offshore EPC projects — used for produced water, sour crude, seawater injection, and chemical injection piping in combined H₂S + Cl⁻ service environments where SS 316L has insufficient corrosion resistance.
Logic, NACE Grades
& Common Errors
Correct ASTM / AISI grade selection requires matching the material to the service environment — temperature, pressure, fluid chemistry, and corrosion regime all determine which grade is appropriate. RR Hydraulic supports grade selection advisory for all EPC piping classes and service conditions.
3.1 — Temperature-Based Grade Selection for Process Piping
| Temperature Range | ASTM Pipe Grade | P-No. | Max Allowable Stress (ASME B31.3) | Selection Notes |
|---|---|---|---|---|
| −29°C to +427°C | A106 Gr.B (CS) | 1 | 138 MPa at 20°C | Universal EPC carbon steel pipe; most common grade |
| −46°C to +260°C | A333 Gr.6 (CS low-temp) | 1 | 138 MPa at 20°C | Low-temperature CS; Charpy impact certified at −46°C |
| Up to +593°C | A335 P11 (1¼Cr-½Mo) | 4 | 93 MPa at 593°C | Alloy steel; high-temp steam; 1¼Cr-½Mo; preheat 200°C |
| Up to +649°C | A335 P22 (2¼Cr-1Mo) | 5A | 82 MPa at 649°C | High-temp alloy; 2¼Cr-1Mo; H₂ service; preheat 250°C |
| Up to +649°C | A335 P91 (9Cr-1Mo-V) | 5C | 121 MPa at 649°C | Highest creep strength CS-type; USC steam; EPRI protocol welding |
| −196°C to +538°C | A312 TP316L (SS) | 8 Gr.1 | 115 MPa at 20°C | Austenitic SS; corrosive service; wide temp range |
| −196°C to +454°C | A312 TP316L (SS) | 8 Gr.1 | See ASME B31.3 App A | Low-C SS 316L; sensitisation-resistant; NACE-compliant |
| −50°C to +315°C | A790 S31803 (Duplex) | 10H | Per ASME B31.3 | Duplex 2205; offshore sour + Cl⁻; above 315°C sigma phase risk |
3.2 — NACE MR0175 Compliant ASTM Grades
A106 Gr.B / A105N (Carbon Steel — NACE)
Carbon steel is NACE MR0175 / ISO 15156-2 compliant when: UTS ≤ 795 MPa; hardness ≤ 22 HRC (≤ 237 HB); normalised heat treatment (A105N — the “N” suffix is mandatory for NACE forgings); and weld HAZ hardness controlled to ≤ 22 HRC by PWHT where required by the P-Number and wall thickness thresholds in ASME B31.3. The normalisation of A105N is specifically required by NACE MR0175 to ensure consistent hardness ≤ 22 HRC — non-normalised A105 (without the N suffix) may have hardness above 22 HRC in isolated pieces from the non-homogeneous microstructure of non-normalised forgings. Individual piece Brinell hardness testing is mandatory for NACE sour service A105N supply.
A312 TP316L (SS 316L — NACE)
SS 316L in the solution-annealed condition (≤ 22 HRC / ≤ 220 HV per ISO 15156-3) is NACE MR0175 compliant for sour service piping. “L” grade (low carbon, C ≤ 0.03%) is mandatory for NACE supply — standard grade 316 (C ≤ 0.08%) may sensitise at weld HAZ temperatures, creating intergranular corrosion susceptibility that disqualifies it for combined H₂S + Cl⁻ service. Solution annealing after welding is required to restore NACE compliance in weld joints of 316 (non-L) — 316L typically does not sensitise with controlled welding heat input and does not require PWHT for NACE compliance. Always verify C ≤ 0.03% on the EN 10204 3.1 MTC for any A312 TP316L lot specified for sour service.
A790 S31803 Duplex 2205 (NACE)
Duplex 2205 in the solution-annealed condition (≤ 28 HRC / ≤ 293 HB per ISO 15156-3 Table A.8) is NACE MR0175 compliant for sour service. Duplex 2205 provides significantly better chloride pitting resistance (PREN ≈ 35) than SS 316L (PREN ≈ 26) — making it the preferred grade for combined H₂S + Cl⁻ service environments where SS 316L pits unacceptably but where the cost of Incoloy 825 or Inconel 625 is not justified. Maximum service temperature for Duplex 2205: 315°C (above this temperature, sigma phase embrittlement risk requires engineering assessment). Ferrite content 40–60% in the annealed condition — verified by metallographic ASTM E562 examination on every EPC Duplex pipe and fitting lot.
A193 B7M (NACE Bolting)
ASTM A193 Grade B7M — 4140/4142 Cr-Mo alloy steel (same alloy as B7) but with modified heat treatment producing maximum hardness ≤ 35 HRC (vs unrestricted hardness for B7). B7M is the NACE MR0175-compliant stud bolt specification for flanged connections in sour service piping. The “M” suffix (modified) specifically indicates the controlled hardness for NACE compliance. Using standard B7 (hardness often above 35 HRC) instead of B7M in a NACE sour service flange connection is a NACE non-conformance — stud bolts in H₂S-containing environments must be ≤ 35 HRC to prevent sulphide stress cracking of the bolt in service. A194 Grade 2HM (modified) heavy hex nuts are the companion nut for B7M stud bolts in sour service.
A182 F316L (SS 316L Forgings — NACE)
A182 F316L forged flanges, fittings, and olets — solution-annealed, C ≤ 0.03%, hardness ≤ 220 HV (annealed) — are NACE MR0175 / ISO 15156-3 compliant for sour service forged components. The same C ≤ 0.03% and solution anneal requirements apply to forged F316L as to tube TP316L — these requirements must be confirmed on the EN 10204 3.1 MTC for NACE supply. For EPC offshore sour service: PMI on 100% of F316L forging lots to confirm 316L vs 316 (both are accepted as “A182 F316” in some non-rigorous specifications, but standard 316 (C ≤ 0.08%) is not NACE-compliant without PWHT). Passivation per ASTM A967 on all SS 316L forged components for offshore and marine service.
A182 F51 Duplex 2205 (Forgings — NACE)
A182 F51 (Duplex 2205, UNS S31803) forged flanges, fittings, threadolets, sockolets, and weldolets — solution-annealed, ≤ 293 HB (≤ 28 HRC), ferrite 40–60% per ASTM E562 — are NACE MR0175 / ISO 15156-3 compliant for sour service. F51 is the dominant Duplex forging grade on EPC offshore projects — it provides NACE compliance and superior chloride pitting resistance vs F316L for offshore produced water, sour crude, and seawater injection systems. Individual piece Brinell hardness on all NACE lots; ferrite count on every lot; PMI on 100% of lots; EN 10204 3.1 with NACE compliance statement; EN 10204 3.2 with DNV/Lloyds for offshore safety-critical Duplex forging supply.
3.3 — Most Common Grade Specification Errors in EPC Procurement
- Specifying “stainless steel” without the grade: “SS pipe” can be 304, 316, 316L, 321, or Duplex — all are stainless steel but none are interchangeable for corrosion resistance or NACE compliance. Always specify the full ASTM standard and grade: “A312 TP316L”
- Specifying A105 instead of A105N for NACE service: Only A105N (normalised) meets NACE MR0175 hardness requirements reliably — non-normalised A105 may have hardness above 22 HRC. The “N” suffix is a contractual requirement for all sour service carbon steel forgings
- Specifying A312 TP316 (not TP316L) for NACE or weldable service: Standard 316 (C ≤ 0.08%) can sensitise at weld HAZ temperatures and is not NACE-compliant without PWHT. Specify 316L (C ≤ 0.03%) for all NACE and weld-intensive SS piping systems
- Accepting A53 pipe instead of A106 for process service: A53 is an ERW (electric resistance weld) or seamless pipe standard for general purposes — it does not require normalising for thick walls and has less stringent mechanical property requirements than A106. Never substitute A53 for A106 in coded process piping above 50 bar
- Using A193 B7 instead of B7M in sour service: B7 (no hardness maximum) will almost certainly exceed 35 HRC — a NACE non-conformance in any H₂S-containing service. Specify B7M explicitly on all NACE sour service flange bolt MRs
- Mixing Duplex grades (S31803 vs S32205 vs S32750) without specifying UNS: The physical appearance of 2205 and Super Duplex 2507 bar is identical; without PMI and UNS specification, the wrong grade may be supplied. Always cite the UNS number alongside the ASTM grade in Duplex procurement: “A790 S31803” not just “Duplex pipe”
- Omitting the ASTM product standard, citing only AISI grade: “AISI 316L” without “ASTM A312 TP316L” or “ASTM A182 F316L” is incomplete — AISI defines composition only, not product form, heat treatment, mechanical properties, or testing. An AISI-only specification can result in supply of composition-correct material with insufficient mechanical properties, incorrect heat treatment, or missing test documentation for code compliance
Material Certification
& Procurement Practices
RR Hydraulic maintains full traceability from certified mill heat to final inspected and packed product shipment across all ASTM and AISI grades. EN 10204 3.1 / 3.2 material certification, dimensional inspection, PMI, NACE hardness, and complete EPC export documentation are standard on all project supply.
4.1 — Inspection & QC Protocol
4.2 — EN 10204 Certification for ASTM-Specified Products
| Certificate | Content | EPC Requirement | When Mandatory |
|---|---|---|---|
| 2.1 / 2.2 | Manufacturer declaration / non-specific | Not acceptable for EPC process piping | Never for coded process piping or pressure equipment |
| 3.1 | Heat-traceable full chem + mech + NDE | Mandatory — all EPC ASTM supply | All A106, A312, A182, A790, A193, A516 EPC supply |
| 3.2 | 3.1 + TPI countersign (DNV/Lloyds/SGS/BV) | Offshore; NACE sour; nuclear; safety-critical | Offshore NACE-critical; nuclear NSSS; API 6A PSL-3/4 |
4.3 — Applications by Industry
EPC Carbon Steel Process Piping (A106 Gr.B)
ASTM A106 Grade B seamless carbon steel pipe is the single most specified material on an EPC project piping material take-off (MTO) — every carbon steel piping class from ASME Class 150# through Class 2500# uses A106 Gr.B as the pipe body material for temperatures from −29°C to +427°C. A typical large Gas Processing EPC project may have 50,000–200,000 metres of A106 Gr.B pipe across all diameters and schedules. RR Hydraulic supplies A106 Gr.B in all standard schedules (Sch 40 through XXS) and NPS sizes (½” through 24″) with EN 10204 3.1 MTCs, dimensional certification per ASME B36.10M, and hydrostatic test certificates on every lot for compliant EPC project supply.
Offshore Duplex Stainless Process Piping (A790 S31803)
ASTM A790 S31803 (Duplex 2205) seamless and welded pipe for offshore platform process piping in produced water, sour crude, wet gas, and chemical injection services where the combination of H₂S, CO₂, and chloride requires both NACE MR0175 compliance and superior pitting resistance beyond SS 316L. A790 S31803 is the most widely specified material on offshore EPC project Duplex piping MRs. Supply requirements: EN 10204 3.1 MTC; ferrite count 40–60% per ASTM E562 on every lot; NACE hardness ≤ 293 HB per lot; PMI on 100% of lots; passivation per ASTM A967. For subsea and safety-critical offshore piping: EN 10204 3.2 with DNV or Lloyds TPI countersign.
High-Temperature Power Piping (A335 P91 / A182 F91)
ASTM A335 P91 seamless pipe and A182 F91 forged fittings and flanges for ultra-supercritical steam piping in advanced coal and gas power plants — main steam headers, hot reheat pipes, and high-energy drain connections operating at 600–650°C and 250–350 bar. P91 is the dominant pipe material for USC power generation EPC projects. Supply requirements: EN 10204 3.1 mandatory; grain size verification (coarse-grained annealed condition); carbon content 0.08–0.12% (critical for P91 grade confirmation — underpins the creep rupture mechanism); C + N content confirmation; individual Brinell hardness on every fitting lot; post-weld anneal at 760–790°C confirmation for pre-fabricated weld assemblies; EPRI TR-117073 welding protocol compliance documentation.
Pressure Vessel Fabrication (A516 Gr.70)
ASTM A516 Grade 70 carbon steel plate for pressure vessel shells, head plates, storage tank shells, and heat exchanger shells in EPC Oil & Gas, Petrochemical, and Power projects. A516 Gr.70 provides UTS 485–620 MPa at minimum cost — the standard vessel plate for moderate-temperature carbon steel pressure vessels in ASME VIII Div.1 service. Normalised condition mandatory for plate thickness above 38 mm (1½”). For low-temperature vessels (below −29°C): specify Supplementary Requirement S5 (Charpy impact testing) on the A516 Gr.70 plate to confirm adequate toughness at the design minimum temperature. EN 10204 3.1 MTC with full plate lot chemistry and mechanical test report. UT inspection per ASME VIII App.12 on all EPC vessel plate ≥ 50 mm thickness.
NACE Sour Service Bolting (A193 B7M / A194 2HM)
ASTM A193 Grade B7M (NACE-compliant Cr-Mo alloy steel stud bolts, ≤ 35 HRC) and A194 Grade 2HM (NACE-compliant heavy hex nuts, ≤ 35 HRC) for flanged joints in all sour service process piping. B7M stud bolts at ≤ 35 HRC prevent sulphide stress cracking of the bolt shank and threads in H₂S-containing process atmospheres — a common failure mode of over-hard standard B7 bolts in sour service piping systems. EPC project piping specifications for sour service should explicitly call out “A193 B7M / A194 2HM” on every sour service bolting line item in the MR — not just “A193 B7” which allows hard bolts. Individual piece Rockwell C hardness testing on every B7M bolt lot is the standard NACE verification practice.
Machined Components and Bar Stock (AISI 4140 / 1045)
AISI 4140 (UNS G41400, ASTM A108 or A434) Cr-Mo alloy steel bar in quenched-and-tempered condition (UTS 690–895 MPa; yield 550–760 MPa; hardness 28–34 HRC) for machined EPC mechanical components — pump shafts, valve stems, actuator shafts, coupling bolts, and structural pins. 4140 Q+T provides the optimal balance of strength, toughness, and machinability for medium-to-heavy section mechanical components. At hardness ≤ 35 HRC: 4140 Q+T is NACE MR0175-compliant for use in H₂S-containing environments as a non-pressure-boundary machined component. For lower-stress general-purpose machined components: AISI 1045 cold-drawn bar (UTS 570 MPa; hardness ≤ 200 HB) is a more economical choice. Specify the ASTM product standard (A108 for cold-drawn bar; A434 for Q+T bar) alongside the AISI grade on all bar stock procurement documents.
4.4 — Export Packaging and Documentation
- All ASTM-specified pipe, tube, and bar supplied with heat number stencilled on every individual piece — the heat number is the traceability link to the EN 10204 3.1 MTC; any piece without a legible heat number is non-traceable and must be rejected from coded process piping service under ASME B31.3
- Colour-coding by material for mixed-material EPC bulk supply: carbon steel (no colour / natural mill finish); SS 316L (white paint band); SS 304L (blue band); Duplex 2205 (yellow band); Super Duplex 2507 (orange band); P91 (red band) — segregation by colour prevents cross-contamination of carbon steel and SS pipe in the field laydown area
- Both pipe ends capped — carbon steel pipe: plastic push-in caps; SS and Duplex pipe: plastic push-in caps (no carbon steel caps — iron contamination on SS bore surfaces causes corrosion pitting at the cap contact zone during transit). P91 alloy pipe: painted end caps with P91 grade label to prevent installation of P91 pipe in incorrect piping classes
- ISPM-15 timber or export cartons; individual bundle weight and dimension on packing list; documentation in waterproof pocket: EN 10204 3.1/3.2 MTC, chemical analysis, mechanical test certificate, Charpy impact (low-temp and cryogenic grades), dimensional certificate (OD/wall/length), hydrostatic test certificate (pipe and tube), PMI report (SS/Duplex/alloy), ferrite count (Duplex), NACE compliance statement (sour service grades), hardness per piece report (NACE bolting B7M; A105N), passivation certificate (SS), FAI report
4.5 — Complete EPC Project Documentation Package
| # | Document | Standard / Format | Mandatory / Conditional | Notes |
|---|---|---|---|---|
| 01 | Material Test Certificate (MTC) | EN 10204 3.1 / 3.2 | Mandatory — all EPC ASTM supply | Full heat-traceable chemistry + mechanical; per heat |
| 02 | Chemical Composition Report | Per applicable ASTM standard limits | Mandatory | All specified elements; C content highlighted for SS grades |
| 03 | Mechanical Properties Report | ASTM E8 tensile / E18 hardness | Mandatory | UTS, yield, elongation; hardness (B7M per piece; Duplex per lot) |
| 04 | Charpy Impact Test Report | ASTM E23 / A370 at design min temp | Mandatory — A333 Gr.6; A516 S5; cryogenic SS | Test temperature; average CVN J-values per heat |
| 05 | Dimensional Inspection Report | ASME B36.10M / B36.19M / ASTM product std | Mandatory | OD, wall, length, ovality; per lot |
| 06 | Hydrostatic Test Certificate | Per ASTM product standard formula | Mandatory — all pipe and tube | Every length; test pressure; hold time; pass/fail |
| 07 | PMI Report (XRF) | 100% — SS / Duplex / alloy steel | Mandatory — all non-CS lots | 316 vs 316L; P11 vs P22 vs P91; 2205 vs 2507 |
| 08 | Ferrite Content Report | ASTM E562 metallographic | Mandatory — A790 S31803 / S32750 | 40–60% (2205); 40–50% (2507); photo of cross-section |
| 09 | NACE Compliance Statement | Hardness + heat treatment declaration | Conditional — sour service grades | A105N ≤ 22 HRC per piece; B7M ≤ 35 HRC per piece; F51 ≤ 293 HB |
| 10 | Passivation Certificate | ASTM A967 | Mandatory — all SS and Duplex lots | Cu-sulphate or water immersion acceptance test |
| 11 | NDE Certificate (UT / MT / PT / ET) | Per ASTM supplementary requirements | Conditional — thick plate; nuclear; offshore critical | S2 (MT) for A182 offshore; App.12 (UT) for A516 thick plate |
| 12 | First Article Inspection (FAI) Report | Project-specific format | Mandatory — new configurations | All parameters; before batch production |
| 13 | TPI Witness Certificate | SGS / BV / DNV / Lloyds | Conditional — EN 10204 3.2; offshore; nuclear | Co-witness chemistry + mechanical + NDE + hardness |
| 14 | ISO 9001:2015 Certificate | Third-party QMS certification | Mandatory — EPC projects | Scope covers ASTM grade steel manufacture |
| 15 | Country of Origin + Packing List | Chamber of Commerce / item-level | Mandatory | HS tariff code; heat number per line item; schedule marked |
| 16 | Commercial Invoice + Bill of Lading | Per INCOTERMS 2020 | Mandatory | Freight forwarder issued |
4.6 — ISO and Quality System Compliance
ISO 9001:2015
Quality Management System governing steel product procurement, heat traceability, dimensional inspection, chemical analysis procedure, mechanical test procedure, hydrostatic test procedure, PMI procedure, ferrite count procedure, hardness test procedure (including individual piece NACE lot procedure), passivation process control, NDE procedure, material marking controls, and full traceability from mill heat to dispatched product. Mandatory for all EPC, offshore, and safety-critical ASTM-specified steel product procurement qualification from RR Hydraulic and all supply chain partners.
ASME B31.3 / B31.1 (Design Codes)
ASME B31.3 (Process Piping) and B31.1 (Power Piping) are the governing design codes that specify which ASTM material standards are acceptable listed materials for coded piping systems. Both codes reference the allowable stress tables in ASME II Part D (Properties — Ferrous) for the S values used in wall thickness calculations. ASTM-specified materials per the listed standards (A106, A312, A182, A790, A335) are directly usable in B31.3/B31.1 designs using the listed S values — non-ASTM materials require engineering qualification per B31.3 Paragraph 323.1.2. The ASTM standard is therefore the gateway to code compliance: specify the ASTM standard on every EPC piping MR line item to confirm code listing status.
NACE MR0175 / ISO 15156
The governing standard for material selection in H₂S sour service — the framework within which specific ASTM grades are accepted or rejected for sour piping and equipment. ISO 15156-2 covers carbon and low-alloy steels (A106 Gr.B normalised, A105N, A335 P-series with hardness limits); ISO 15156-3 covers CRAs (A312 TP316L annealed, A790 S31803 annealed, A182 F51, Incoloy 825, Inconel 625). The procurement engineer must cross-reference the ASTM grade against the relevant ISO 15156 section to confirm the specific heat treatment condition, hardness limit, and test requirements for NACE compliance — these requirements are the additional supply conditions beyond the base ASTM standard requirements for all sour service ASTM-specified material supply.
EN 10204 vs ASTM Mill Test Reports
A common procurement ambiguity on international EPC projects: ASTM standards reference “certified test report” (CTR) or “manufacturer’s test report” (MTR) as the material certification document — these ASTM mill test report formats are not identical to EN 10204 3.1 certificates, but both serve the same function (heat-traceable material test records). For EPC projects explicitly requiring EN 10204 3.1: the supplier must issue a document that conforms to the EN 10204 3.1 format (manufacturer’s name, product form, alloy grade, heat number, chemical analysis results, mechanical test results, and manufacturer’s inspector declaration) — not just an ASTM-format mill certificate. Some international EPC projects accept ASTM mill certificates as equivalent to EN 10204 2.1 — verify the project quality plan’s specific interpretation before accepting non-EN-10204-format certificates as 3.1 equivalents.
Submit your ASTM grade, product form, dimensions, and quantity to RR Hydraulic for a complete, certified commercial offer.