Hastelloy C-276 Cross Four-Way Connector For Piping Systems
Hastelloy C-276 Cross is a four-way pipe connector manufactured
from Hastelloy C-276 superalloy primarily used in piping systems to
achieve four-way diversion or confluence of media (usually a
"cross-shaped" structure). Its performance and depth of application
combine the characteristics of Hastelloy C-276 alloy with the
functional requirements of four-way pipe fittings:
1. Core material characteristics and support for the function of
the four-way link
Hastelloy C-276 is a nickel-molybdenum-chromium superalloy (typical
composition: Ni≈57%, Mo≈16%, Cr≈15.5%, Fe≈5%, W≈4%, C≤0.01%), and
its characteristics directly determine the applicable scenarios of
the cross-link:
(1) Super corrosion resistance
▶ It is suitable for both oxidizing and reducing media: it can
withstand the corrosion of wet chlorine, hypochlorite, chloride
(containing high concentration of Cl⁻), sulfuric acid (less than
90%), hydrofluoric acid (HF), organic acid (such as formic acid,
acetic acid) and mixed acids (such as H₂SO₄+HF), especially in
high-temperature corrosion environments above 60°C, far exceeding
316 stainless steel, duplex steel (2205), etc.
▶ Outstanding resistance to local corrosion: pitting corrosion
resistance (PREN≈70, much higher than 316), crevice corrosion
(avoiding corrosion caused by sealing gaps at cross-way interfaces)
and intergranular corrosion (low-carbon design + tungsten element
inhibits carbide precipitation).
(2) High temperature mechanical stability
Maintain high strength (tensile strength at room temperature
≥895MPa, still ≥690MPa at 538°C) in ≤1000°F (538°C), and can
withstand the stress caused by medium pressure fluctuations or
thermal expansion and contraction to avoid deformation or cracking.
(3) Good processing and welding performance
It can be forged and machined, and the use of matching wires (such
as ERNiCrMo-4) during welding reduces the risk of thermal cracks
and ensures the connection strength of the cross-sections (suitable
for butt weld or socket weld structures).
2. Applicable working conditions and industry scenarios
The core logic of Hastelloy C-276 crosses is that "media
corrosiveness exceeds the tolerance range of conventional alloys",
and specific scenarios include:
(1) Chemical acid-alkali treatment
▶ Concentrated nitric acid and hydrofluoric acid mixture pipelines:
In the fluorine chemical industry, it is used to connect reactors,
condensers and storage tanks to resist strong corrosion of mixed
acids (316 stainless steel typically has a lifespan of < 6
months in this environment, and C-276 can be extended to more than
5 years).
▶ Wet chlorine pipeline in chlor-alkali industry: The diversion
pipeline between the chlorine gas drying tower and the absorption
tower is resistant to the corrosion of hydrochloric acid and
hypochlorous acid generated by wet chlorine (Cl₂+H₂O).
(2) Environmental protection and hazardous waste treatment
High-concentration chlorine-containing wastewater pipelines: In the
landfill leachate treatment system, the four links connecting the
conditioning tank, oxidation tower, and sedimentation tank are
resistant to the synergistic corrosion of Cl⁻ (>10,000ppm) and
oxidants in wastewater.
(3) Oil and gas exploitation and processing
Acid gas field gathering and transportation pipelines: Four-way
pipelines connecting gas wells, separators, and desulfurization
devices, which are resistant to corrosion of H₂S (>5%), CO₂
(>10%) and formation water (high Cl⁻), and avoid sulfide stress
cracking (SSCC).
(4) Pharmaceutical and food-grade chemicals
Sterile injection production pipeline: Four-way distribution of
purified water, water for injection and chemical solution, meeting
FDA requirements for material purity (C-276 no heavy metal
precipitation), and resisting corrosion from detergents such as
citric acid and hydrogen peroxide.
3. Key points of manufacturing process
Due to the high high temperature strength and high tendency of
Hastelloy C-276 to work harden, its four-way manufacturing requires
strict control of the process:
(1) Forging and forming
The hot forging process (forging temperature 1150~1200°C) is used
to avoid cracks caused by cold working, ensure uniform internal
structure (grain size control at ASTM 5~8), and improve the
anti-corrosion fatigue performance.
(2) Welding process
Before welding, the surface oxide scale needs to be removed (with a
stainless steel wire brush or pickling), tungsten argon arc welding
(GTAW) is used, ERNiCrMo-4 is used for welding wire, and the
temperature between layers is ≤ 150°C to avoid embrittlement caused
by the precipitation of harmful phases (such as μ phase) in the
heat-affected zone (HAZ).
(3) Heat treatment
After welding, solution treatment (1120~1150°C insulation for 1~2
hours, air cooling) is required to eliminate welding stress and
dissolve the dissolved carbide to restore corrosion resistance.
4. Advantages over other materials
| Comparison Item | Hastelloy C-276 Crosses | 316 Stainless Steel Crosses | Duplex Steel (2205) Crosses |
|---|
| Resistance to Cl⁻ Corrosion | Withstands 30% NaCl solution (boiling state) | Pitting occurs in 5% NaCl solution (room temperature) | Withstands 20% NaCl solution (room temperature) |
| High-temperature Strength (500℃) | Tensile strength ≈700MPa | ≈400MPa | ≈550MPa |
| Cost | Approximately 8~10 times that of 316 | Reference value | Approximately 3 times that of 316 |
| Service Life | Over 10 years in critical working conditions | Typically ＜1 year (in strong corrosive environments) | 3~5 years (in moderately corrosive environments) |
DINGSCO
Hunan Dinghan New Material Technology Co., Ltd. (DINGSCO) specialized in Nickel Based Corrosion Resistant and High
Temperature alloys products which used in the world’s most technically demanding industries and applications.We are
dedicated to providing our customers with best quality products,
fastest possible deliveries, most competitive prices of Nickel
Based Corrosion Resistant and High Temperature alloys in bars, rods, forged flanges, valve parts (Ball, Stem, Seat Ring, etc), forged shapes (shafts, discs, blocks, hubs, rings, cylinders and other custom shapes) according to ASTM, ASME, API, AMS, NACE and other industry standards.
PROFESSIONAL NICKEL ALLOY MANUFACTURER
- Monel, Incoloy, Inconel, Hastelloy
- VIM, ESR, Forging, Heat treatment, Machining
- Round Bar, Ball, Stem, Ring, Flange, etc
- ISO9001, API-6A, API-20B, PED, NORSOK
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