Hastelloy B-2 Springs Manufacturer

Hastelloy B-2 Springs

Hastelloy B-2 has significant resistance to reducing environments like hydrogen chloride gas, and sulfuric, acetic and phosphoric acids, making Hastelloy B-2 springs an option for mechanical components in reducing environments. The presence of Molybdenum provides significant corrosion resistance to reducing environments. Alloy B-2 provides resistance to pure sulfuric acid and a number of non-oxidizing acids.

Hastelloy B-2 Springs FAQs

What is Hastelloy B-2 and why is it used for springs?

Hastelloy B-2 is a nickel molybdenum alloy, high in molybdenum at roughly 26 to 30 percent, with essentially no chromium. It exists for one job: significant resistance to reducing environments such as hydrogen chloride gas and sulfuric, acetic, and phosphoric acids. The molybdenum content delivers the corrosion protection in those reducing settings, and the alloy handles pure sulfuric acid along with other non-oxidizing acids. As a spring material it is solid solution strengthened, so properties come from cold work rather than aging. Density is 0.33 lb/in³ and modulus of elasticity is 31.4x10^3 ksi.

What applications use Hastelloy B-2 springs?

Chemical processing is the core market. The molybdenum content makes the alloy usable for mechanical components inside reducing environments, so B-2 springs go into valves, pumps, seals, and instrumentation exposed to hydrochloric acid, sulfuric acid, and organic acids such as acetic and phosphoric. Acid regeneration and pickling equipment is another common home for the grade. Modulus of rigidity is 10196 ksi, the value you use for rate calculations, and thermal conductivity is 85 Btu/(hr/ft²/in/°F). Coefficient of expansion is 6.0 μin/in.-°F at 68°F, lower than either Monel grade or Inconel 600.

Where should Hastelloy B-2 not be used?

Oxidizing conditions. B-2 carries essentially no chromium, so it has no passive film to defend itself, and the same chemistry that makes it excellent in hydrochloric acid makes it a poor choice in nitric acid, in aerated or oxidizing acid streams, and specifically in ferric chloride or cupric chloride solutions, where attack can be rapid. Oxidizing metal ion contamination in an otherwise reducing acid is the common field failure. If your process swings between reducing and oxidizing states, or you cannot rule out ferric or cupric ion carryover, B-2 is the wrong grade for the spring.

How does Hastelloy B-2 compare with Hastelloy C-276?

B-2 is the specialist and C-276 is the generalist. B-2 relies on molybdenum alone and outperforms C-276 in strongly reducing acid, particularly hydrochloric and pure sulfuric. C-276 adds chromium and tungsten to the nickel molybdenum base, which costs some performance in pure reducing acid but buys tolerance for oxidizing conditions, oxidizing chlorides, and mixed or upset chemistry. Specify B-2 when you know the stream stays reducing and clean of oxidizers. Specify C-276 when the chemistry varies, when oxidizers may be present, or when one spring design has to cover several service points.

What are the maximum service temperature and minimum wire size for Hastelloy B-2 springs?

The Technical Specification table lists a Max Temperature of 260°C (500°F) and a Min Size of 0.005 in (0.130 mm), finer than either Monel grade CTI publishes and fine enough for small precision springs. Electrical resistivity is 825 μΩ.cm. The temperature figure is a spring service limit rather than an alloy melting or oxidation limit, and for B-2 there is a metallurgical reason to respect it, because prolonged exposure in the intermediate temperature range promotes ordering and intermetallic formation that reduces ductility. Give CTI both the peak temperature and the dwell time at temperature.

Does Hastelloy B-2 need heat treatment after coiling?

B-2 is solid solution strengthened and cannot be age hardened, so there is no strengthening heat treatment to apply. What cold coiled B-2 springs do need is a stress relief to reduce residual coiling stress and stabilize free length, and the cycle has to be chosen so the alloy is not held in the range where intermetallic phases form and ductility drops. That is a genuine constraint on nickel molybdenum alloys and a reason not to treat a stainless steel stress relief recipe as transferable. CTI performs heat treating in-house in Houston, so the cycle is set and recorded with the coiling job.

Why does Coiling Technologies ask about your process chemistry before quoting Hastelloy B-2 springs?

Because this grade is easy to specify wrongly. B-2 is excellent in one chemistry family and poor in another, and the difference often comes down to contaminants a drawing never mentions, such as ferric ion carryover, oxygen ingress, or an upset condition during startup. Supply the acid and its concentration, operating and peak temperature, aeration state, any known metal ion contamination, and expected cycle life alongside your load and geometry requirements. CTI's engineering team can then confirm B-2 is right or recommend C-276 or a nickel copper grade before tooling and material are committed.