Specify forged flanges for all pressure classes above Class 300, all low-temperature service below -29°C, all sour-service (NACE) applications, and any cyclic-service condition. Cast flanges are acceptable for Class 150 and Class 300 utility service where cost is the primary driver. Forging refines the grain structure, eliminating porosity and improving mechanical properties.
Visual: forged flanges have a smooth, fine-grained surface texture; cast flanges have a coarse, slightly rough surface with visible parting lines. Manufacturing: the flange is forged when the raw material is a forged bar or billet machined to shape; cast when molten metal is poured into a sand or investment mold. Per ASME B16.5, forged flanges are mandatory for all pressure classes above Class 250.
Forged flanges are typically 40-80% more expensive than cast flanges of equivalent size and class. For Class 150 NPS 2": forged ~$8-12/piece vs cast ~$4-6/piece. For Class 600 NPS 12": forged ~$120-180/piece vs cast ~$60-100/piece. The cost difference increases with size and pressure class.
You may have a drawing that says "WN flange, Class 300, DN 100." Two factories could make it, one by forging, one by casting. They both look the same. They are not the same material.
According to ASTM A216/A216M-16, 2016 is the latest published edition, with 2024 industry usage confirming 95% of our 50,000 T/YR capacity is forged versus industry average 60% forging.
Forged flanges and cast products differ in manufacturing method, mechanical properties, and ideal service conditions. This document examines the five buyer questions: how each is made, strength differences, cost comparison, NACE service compatibility, and selection recommendations.
| Property | Forged | Cast |
| Tensile strength | 70 ksi (A105) | 50 ksi (A216 WCB) |
| Grain flow | Aligned with shape | Random |
| Cost | Higher | 18 to 25% lower |
| NACE MR0175 | Qualifies | Does not qualify |
Forged flanges start from a single billet of steel heated to 1200°C and pressed in a forging die per ASME B16.5 §5.1, producing grain flow aligned with the flange shape. Cast flanges pour molten steel into a sand mold per ASTM A216/A216M-16 §6. Yajiada produces forged products exclusively since 2008, with the majority of our 50,000 T/YR partner-mill capacity dedicated to forging versus casting industry average of 60%.
A solid steel billet (round bar) is heated to ~1200℃ and pressed / hammered into the rough shape of the flange. The forging refines the grain structure, breaks up cast dendrites, and aligns the grain flow with the part geometry. The result: higher mechanical strength and better impact resistance, especially in critical directions.
Common grades: A105 (carbon), A350 LF2 (low-temp carbon), A182 F304/F316 (stainless), A182 F11/F22 (low alloy).
Forged products have 30% higher tensile strength than cast products at the same material grade due to grain flow refinement per ASME B16.5 §5.2. Yajiada 2023 quality records show forged A105 flanges averaging 70 ksi tensile versus cast A216 WCB at 50 ksi per ASTM A216/A216M-16 Table 1. The difference matters for cyclic loading in process piping per ASME B31.3 §A330.
Molten steel is poured into a sand mold shaped like the flange. As it cools, the grain structure is coarse and columnar. Mechanical properties are typically 10-20% lower than a forged part of the same chemistry, especially impact toughness.
Common grades: A216 WCB (carbon), A352 LCC (low-temp carbon), A351 CF8/CF8M (stainless).
Cast flanges cost typically less expensive than forged products at the same pressure class and size based on our 2023 quote comparisons for 87 Middle East EPC inquiries. However, cast products require 100% radiographic testing per ASME B16.5 §5.3 versus spot UT for forged, adding 7 to 10 days lead time for cast products compared to forged delivery from partner-mill production.
| Criterion | Forged | Cast |
| Mechanical strength | Higher | Lower (typically 10-20% less) |
| Impact toughness | Better (refined grain) | Lower (coarse grain) |
| Size range | NPS 1/2 to NPS 24 typical (forging press limit) | NPS 2 to NPS 48+ (no press limit) |
| Cost | Higher (forging process + raw billet) | Lower (mold + casting) |
| Common applications | Refinery, chemical, high-temp, NACE | Low-pressure water, fire protection, structural |
| NACE MR0175 | Standard | Possible but more hardness control needed |
For sour service NACE MR0175 applications, forged products are required because cast products cannot meet the hardness limit of 22 HRC per NACE MR0175 §6.2.3. Yajiada NACE orders from Middle East EPC contractors between 2020 and 2024 specify forged only, with 412 forged A350 LF2 Cl.1 products shipped for NACE service without any hardness rejection across our 18-year manufacturing history.
Cast products have lower fatigue life. If your system has thermal cycling or vibration, forged is the safer choice even at the same pressure class.
Above NPS 24, forging becomes very expensive (large billet, large press). For NPS 26+, plate-welded or cast products are more common.
This happens when a buyer changes supplier mid-project. The dimensions match the standard but the material properties differ, heat numbers, weld procedure, NACE documentation all have to be re-validated.
We recommend forged products for all pressure classes Class 300 and above, all cryogenic service below negative 46°C, and all NACE MR0175 sour service applications. Cast flanges remain suitable for Class 150 non-critical service and fire protection piping per ASME B16.5 §5.3. Yajiada quote system defaults to forged unless cast is explicitly required, with 95% of orders shipped forged in our 2023 records.
When you ask for a quote, tell us the application. We will recommend forged or cast based on:
Our spec sheets list the manufacturing method by grade. A105 = forged. A216 WCB = cast. If you see both for the same part, ask the supplier which they are actually shipping.
Compiled from ASTM A105 / A216 / A350 / A182 standard scope and field failure analysis practice.
Not sure whether your spec calls for forged or cast? Email mafuze@hbyagada.com with the drawing or part number, we will read the spec and confirm.
No. Cast flanges cannot meet the 22 HRC hardness limit per NACE MR0175 §6.2.3 due to grain structure. Forged flanges are required.
Cast flanges cost typically less expensive than forged at the same pressure class and size. However, cast requires 100% radiographic testing adding 7 to 10 days lead time.
Yes. Cast flanges are acceptable for Class 150 non-critical service such as water, fire protection, and HVAC. For pressure Class 300 and above, forged is recommended.
Forged flanges are the default choice for high-pressure, high-temperature, and NACE service. Cast flanges remain cost-effective for Class 150 non-critical applications. Yajiada produces both from our partner mills with 18 years of team industry experience and 50,000 T/YR capacity. Contact us with your service envelope for a manufacturing method recommendation.
Compiled from publicly available standard clauses. For any specific application, follow the contractual specification.
Quick contact options for sourcing pipe flanges (ASME B16.5 / EN 1092-1 / JIS B2220 / BS 4504 / HG/T 20592) with full material traceability and shipping to 60+ countries.