How to Order Forged Fittings
Forged fittings are small-bore piping components used primarily for NPS 2” and below (though ASME B16.11 covers sizes up to NPS 4”). They connect small-bore pipe runs via socket weld (SW) or threaded (THD) connections, and are manufactured by forging bar stock into shapes such as elbows, tees, couplings, unions, and plugs.
Pressure classes range from Class 2000 to Class 9000, depending on the connection type. The dimensional and rating standard is ASME B16.11.
Core Attributes
Every forged fitting line item in an RFQ or purchase order must include all of the following attributes.
| # | Attribute | Values / Options | Notes |
|---|---|---|---|
| 1 | Fitting type | 90° elbow, 45° elbow, tee, cross, full coupling, half coupling, union, cap, bushing (flush or standard), hex head plug, round head plug, nipple (pipe nipple) | Specify “flush bushing” vs “standard bushing” explicitly; flush bushings sit flush with the fitting bore |
| 2 | Connection type | Socket Weld (SW) or Threaded (THD) | Threaded fittings follow NPT per ASME B1.20.1 by default; specify BSP (BSPP/BSPT per ISO 7-1) if required |
| 3 | Dimensional standard | ASME B16.11 | Always state the standard; do not assume the supplier will default to B16.11 |
| 4 | Nominal size | NPS 1/8” through NPS 4” | For reducers, bushings, and reducing tees: state both run and branch sizes (e.g., “3/4” x 1/2"") |
| 5 | Pressure class | SW: 3000, 6000, 9000 · THD: 2000, 3000, 6000 | Class 9000 is SW only. Class 2000 is THD only. Class 3000 and 6000 are available in both |
| 6 | Material specification | See material table below | Always specify the full ASTM designation and grade |
Material Specifications
| Service | ASTM Standard | Common Grades |
|---|---|---|
| Carbon steel | ASTM A105 | A105 (single grade) |
| Alloy steel | ASTM A182 | F11 (1-1/4Cr-1/2Mo), F22 (2-1/4Cr-1Mo), F5 (5Cr-1/2Mo), F9 (9Cr-1Mo), F91 (9Cr-1Mo-V) |
| Stainless steel | ASTM A182 | F304, F304L, F316, F316L, F321, F347 |
| Duplex stainless steel | ASTM A182 | F51 (2205), F53 (2507), F55 (S32760) |
| Low-temperature CS | ASTM A350 | LF2 (down to -46°C) |
Optional and Special Attributes
| Attribute | When Required | Details |
|---|---|---|
| NACE MR0175 / ISO 15156 | Sour service (H₂S-containing environments) | Limits hardness to 22 HRC max for CS (A105); specifies solution-annealed condition for SS and duplex |
| Hardness testing | NACE service, or per project spec | Report max hardness values on MTR; specify test method (Brinell, Rockwell) |
| Special marking | Per project or client spec | Heat number, material grade, class, size, manufacturer logo; paint/ink marking vs hard stamping (low-stress stamp for alloy/SS) |
| Certificates | Almost always required | EN 10204 Type 3.1 (MTR) minimum; Type 3.2 for critical services. Specify if PMI (Positive Material Identification) is required |
| Surface treatment | Specific environments | Hot-dip galvanizing per ASTM A153 for threaded CS fittings in outdoor/corrosive environments |
Example Line Items
Correct
20 pcs - 90° Elbow, ASME B16.11, NPS 1”, Class 3000, Socket Weld, ASTM A105, NACE MR0175, MTR EN 10204 3.1
This line item is complete: it specifies the fitting type, standard, size, class, connection type, material, sour service compliance, and certificate requirement.
Incorrect
20 - CS elbow 1” SW 3000#
This line item is missing: the dimensional standard (B16.11), the exact material specification (A105 vs A350 LF2), the elbow angle (90° vs 45°), NACE requirements, and the certificate type. The supplier must guess or ask for clarification.
Common Pitfalls
| Pitfall | Why It Matters |
|---|---|
| Omitting the pressure class | A 3000# fitting has a different wall thickness and pressure-temperature rating than a 6000# fitting of the same size. Without the class, the supplier cannot quote |
| Writing “NPT” for the connection type instead of “THD” | NPT refers to the thread standard (ASME B1.20.1); the connection type in B16.11 is “threaded.” If BSP threads are needed, you must specify this explicitly; otherwise NPT is assumed |
| Not specifying flush vs standard bushing | A standard bushing has a hex head for wrench grip; a flush bushing has no hex and sits flush inside the fitting. They are not interchangeable |
| Missing reducing sizes | For reducing tees, couplings, and bushings, both the larger and smaller sizes must be stated (e.g., “Reducing Tee 1” x 1” x 1/2"" or “Bushing 1” x 3/4"") |
| Class 2000 specified for socket weld | Class 2000 exists only for threaded fittings. Socket weld classes are 3000, 6000, and 9000 |
| Material mismatch with connecting pipe | The forged fitting material must be compatible with the pipe material per the piping class. A105 fittings on A312 TP316L pipe is a material mismatch that will be rejected at inspection |
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