Forged pipe fittings and cast pipe fittings are two mainstream manufacturing processes for products in industrial piping systems. The core difference comes from the different material forming methods, which lead to significant differences in performance, application scenarios, and costs. The following is a comparison of the dimensions of process principles, performance parameters, application scenarios, etc., with specific industry standards and data support attached:
1. Comparison of process principles and manufacturing processes
| Comparative Item | Forged Pipe Fittings | Cast Pipe Fittings |
| Molding principle | The solid metal is subjected to pressure by forging equipment (such as hydraulic presses and forging hammers) to cause plastic deformation and form the desired shape. | Pour the molten metal (such as molten iron, molten steel) into the mold, and obtain the molded part after cooling and solidification. |
| Typical process steps | Raw material cutting → heating → forging → deburring → heat treatment (normalizing/quenching) → machining threads/grooves → non-destructive testing. | Mold preparation → molten metal pouring → cooling demoulding → gate cutting → heat treatment (annealing) → machined surface → pressure test. |
| Material utilization rate | About 80%-90% (basically no material loss during plastic deformation). | About 60%-70% (gates and risers need to be reserved, and defects such as shrinkage cavities may occur). |
| Representative standard | ASME B16.11 (forged pipe fittings), ISO 4143 (forged steel pipe fittings). | ASTM A216 (cast iron pipe fittings), ASME B16.3 (malleable cast iron pipe fittings). |
2. Differences in performance and mechanical properties
Comparison of mechanical properties
Tensile strength: Forged carbon steel pipe fittings (such as ASTM A105) can reach more than 485 MPa, while cast carbon steel pipe fittings (such as ASTM A216 WCB) are about 485-655 MPa.
Elongation: Forged parts ≥30%, castings are usually ≤25%, and the forging process has better impact resistance due to the continuous metal fiber streamlines (refer to ISO 6892-1 metal tensile test standard).
Density: Forged parts have no pores, and the density is close to the theoretical value (such as carbon steel 7.85 g/cm³). Castings may have tiny pores, and the density is reduced by about 3%-5%.
Microstructure differences
Forged parts: The metal grains are rolled and refined to form a fibrous structure distributed along the force direction, and the fatigue strength is 20%-30% higher than that of castings.
Castings: Dendritic crystals are easily formed during the cooling process. If the pouring temperature is not properly controlled, defects such as shrinkage and slag inclusion may occur.
3. Application scenarios and industry selection basis
Core applications of forged pipe fittings
High-pressure and high-temperature scenarios: Forged pipe fittings must be used for high-pressure pipelines (such as above 10 MPa) in petroleum refining units. ASME B31.3 stipulates that chromium-molybdenum steel pipelines with a design pressure ≥4.0 MPa must use forged elbows (case: the cryogenic pipeline system of a certain LNG receiving station uses forged 304L pipe fittings at -162℃).
Critical safety system: The main steam pipeline of a nuclear power plant uses forged tees because the creep resistance of forged parts (100,000 hours creep rupture strength ≥100 MPa at 450℃) meets the requirements of ASME BPVC Section III.
Typical scenarios for cast pipe fittings
Low-pressure large-diameter pipes: In urban water supply and drainage systems, cast iron pipe fittings (ASTM A888) above DN300 are widely used due to their low cost and good corrosion resistance. In a municipal sewage project, the cost of cast ductile iron elbows of DN600 is only 1/3 of that of forged parts.
Non-critical working conditions: The chilled water pipes of HVAC systems (pressure ≤1.6 MPa) often use cast carbon steel pipe fittings (ASTM A216 WCC), which are more cost-effective than forged parts (the unit price of DN100 forged flange is about 2.5 times that of castings).
4. Comparison of cost and production efficiency
Unit cost
Forged pipe fittings: The mold cost is high (a set of forging molds is about 50,000-100,000 yuan), but it is suitable for mass production. The unit price of DN50 forged tees is about 80-120 US dollars (based on the quotation of Chinese factories).
Cast pipe fittings: The mold cost is relatively low (sand casting molds are about 10,000-30,000 yuan), but complex shapes require multiple molds, and the unit price of a DN50 cast tee is about 30-50 US dollars (Alibaba International Station 2024 data).
Production cycle
Forging: The production cycle of small and medium batches (less than 100 pieces) is about 7-10 days, requiring heating and multiple forging.
Casting: The batch production cycle is shorter (5-7 days), especially suitable for large castings (such as DN1000 and above), but it is necessary to wait for the metal to cool.
5. Industry standards and quality control
Forged pipe fittings inspection: ASME B16.11 requires all forged pipe fittings to undergo magnetic particle testing (MT), and high-pressure parts require additional ultrasonic testing (UT). The UT acceptance standard for forged elbows in a certain refining project is a defect size of ≤1.5mm (reference API 5L).
Casting pipe fittings inspection: ASTM A216 stipulates that castings must undergo tensile and impact tests, and cast iron pipe fittings for water supply and drainage must pass the ISO 6594 pressure test (no leakage at 1.5 times the working pressure).
6. Typical cases and misunderstandings
Wrong application case: A chemical company used cast carbon steel elbows for hydrofluoric acid-containing media (pressure 6.4 MPa). Due to micropores in the castings, the media leaked and was eventually replaced with forged 316L pipe fittings (refer to NACE MR0175 corrosion resistance standard).
Correct selection case: A municipal heating pipe network (1.6 MPa, 150℃) selected QT450-10 ductile iron pipe fittings, which have a tensile strength of 450 MPa and an elongation of 10%, meeting the GB/T 13295 heating pipe standard, and the cost is 40% lower than that of forged parts.
Conclusion
Forged pipe fittings are known for their high strength and reliability, and are suitable for high-pressure, high-temperature, and critical safety systems; cast pipe fittings dominate the low-pressure, large-diameter, and non-critical working conditions market with their cost advantages and process flexibility. When selecting a model, it is necessary to combine the characteristics of the medium, the safety level, and the cost budget, refer to ASME, ASTM, and other standard specifications, and consult professional suppliers when necessary (such as Jianzhi, which can provide customized solutions for forged/cast pipe fittings).
Forged pipe fittings and cast pipe fittings play different roles in industrial systems: forged solutions perform well in high-risk, high-pressure situations, while malleable cast iron fittings provide an economical, efficient, and versatile alternative for most commercial applications. Jianzhi Group’s malleable cast iron pipe fittings series meets ASTM, ASME, and ISO standards, and achieves a perfect balance between durability, economy, and ease of installation. Contact us now to get a free China malleable cast iron fittings catalog or a custom quote.