Forged flanges in nickel alloy and stainless steel stacked after machining at Shanghai Hangbo Alloy Group

Weld neck flange in a nickel-based alloy with a machined raised face and drilled bolt holes

Concentric reducers in nickel alloy and stainless steel after dimensional inspection

Butt weld equal tee to ASME B16.9 in nickel-based alloy with bevelled ends

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Nickel alloy flanges and pipe fittings: technical knowledge

Name: Shanghai Hangbo Alloy Group Co., Ltd.
Address: Shanghai, Shanghai, 201900, CN
Telephone: +86 15618279078

How to specify, dimension, mark, weld and inspect nickel alloy flanges, elbows, tees and seamless pipe. Every guide is written and reviewed by the materials engineers who sign the certificates.

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Technical knowledge: nickel alloy flanges and pipe fittings

2026-09-20 · 9 min read
Welding Inconel 625 to carbon steel: buttering, filler and control
The reliable way to join Inconel 625 to carbon steel is to butter the carbon steel bevel first with ERNiCrMo-3, then complete the joint to the nickel alloy. This keeps the dilution zone…
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2026-09-19 · 9 min read
Heat numbers and mill test certificates: reading the paperwork properly
A heat number is the identifier that links a finished component back to the melt from which it came, and the mill test certificate is the document that proves what that melt contained.…
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2026-09-18 · 8 min read
ASTM B564 explained: what the flange material specification actually covers
ASTM B564 is the material specification for nickel alloy forgings, including the blanks used to machine flanges, fittings and valve bodies. It defines chemistry, mechanical properties and…
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2026-09-17 · 8 min read
Positive material identification: the control that prevents mixed material
Positive material identification verifies that the installed alloy actually matches the specification. Portable X-ray fluorescence confirms most alloying elements in seconds but cannot…
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2026-09-16 · 8 min read
Duplex 2205 flanges to ASTM A182 F51: what the grade actually delivers
Duplex 2205 delivers roughly twice the yield strength of 316L and a PREN of 35 to 38 against about 26, at a price close to 316L once wall thickness reduction is counted. It is the default…
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2026-09-15 · 8 min read
ASTM B366 explained: the specification behind nickel alloy fittings
ASTM B366 is the specification for factory made wrought nickel and nickel alloy butt weld fittings: elbows, tees, reducers, caps and stub ends. It defines material, heat treatment and…
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2026-09-14 · 9 min read
Inconel 625 flanges to ASTM B564: properties, classes and ordering notes
An Inconel 625 flange is a forged nickel-chromium-molybdenum-niobium component supplied to ASTM B564, UNS N06625, dimensionally to ASME B16.5 or B16.47. Specify it when chlorides, sour gas…
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2026-09-13 · 9 min read
Super duplex 2507 for subsea and high chloride piping
Super duplex 2507 raises chromium, molybdenum and nitrogen above duplex 2205 to reach a PREN above 40, which is what makes it viable for warm brine, subsea manifolds and high velocity…
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2026-09-12 · 8 min read
Inconel 718 flanges and bolting: strength, hardness limits and sour service
Inconel 718 is the precipitation hardening nickel alloy to specify when the joint needs yield strength above 1000 MPa, relaxation resistance at elevated temperature, or compliance with NACE…
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2026-09-11 · 8 min read
Incoloy 825 for sulphuric and phosphoric acid piping
Incoloy 825 is the economic middle ground between 316L and the high molybdenum nickel alloys. Its 38 to 46 % nickel, 19.5 to 23.5 % chromium and 2.5 to 3.5 % molybdenum, stabilised with…
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2026-09-10 · 8 min read
Flange facing types: raised face, flat face, ring joint and tongue and groove
The facing decides how the gasket is compressed and therefore whether the joint seals. Raised face with a spiral wound gasket is the default for most process piping. Flat face is used with…
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2026-09-09 · 9 min read
Hastelloy C-276 flanges: the reference alloy for aggressive chemical duty
Hastelloy C-276 is the reference alloy when a stream contains reducing acids, oxidising contaminants and chlorides at the same time. With about 16 % molybdenum, 15.5 % chromium and 4 %…
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2026-09-09 · 9 min read
Welding duplex stainless flanges: keeping the phase balance
Duplex welding is about preserving the ferrite to austenite balance. Use an over alloyed filler such as ER2209 for 2205 or ER2594 for 2507, keep heat input within the qualified range,…
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2026-09-08 · 7 min read
Inconel 600 vs Inconel 625: which alloy for your piping?
Inconel 600 is a nickel-chromium alloy with no deliberate molybdenum addition, so it resists caustic, high temperature oxidation and chlorine bearing gases but pits readily in warm chloride…
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2026-09-07 · 9 min read
Titanium Grade 2 for seawater, chlorine and desalination piping
Titanium Grade 2 is commercially pure titanium with an oxide film that is stable in seawater at any practical temperature, which is why it is the reference material for desalination heat…
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2026-09-06 · 9 min read
ASME B16.5 pressure temperature ratings: how to read the tables
A pressure class is not a pressure rating. ASME B16.5 assigns each material group a maximum allowable working pressure that falls as temperature rises, so a Class 300 flange in one alloy…
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2026-09-05 · 8 min read
Inconel 601 and 617 for elevated temperature fittings and ducting
For metal temperatures above roughly 600 C, select on oxidation and creep rather than on pitting resistance. Inconel 601 gives outstanding oxidation and carburisation resistance to about…
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2026-09-05 · 8 min read
Crevice corrosion under gaskets and deposits: the hidden failure mode
Crevice corrosion occurs where a narrow gap prevents the fluid from refreshing, so the local chemistry becomes aggressive and the passive film breaks down. It starts at lower temperature…
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2026-09-04 · 8 min read
Monel 400 in seawater and hydrofluoric acid service
Monel 400 is a nickel copper alloy with about 63 % nickel and 30 % copper that performs exceptionally well in flowing seawater and in anhydrous hydrofluoric acid. It resists chloride stress…
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2026-09-03 · 7 min read
MSS SP-25 marking: the cheapest traceability you will ever buy
MSS SP-25 is the standard marking system for valves, flanges, fittings and pipe unions. It defines the required marks: manufacturer name or trademark, material designation, pressure class…
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2026-09-02 · 7 min read
Incoloy 800H vs 800HT: what the extra letters actually buy
Incoloy 800H and 800HT are not marketing variants of the same grade. 800H requires a controlled carbon content and a grain size of ASTM 5 or coarser to obtain elevated temperature allowable…
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2026-09-01 · 8 min read
Duplex 2205 vs 316L: the cost case, not just the corrosion case
Duplex 2205 costs more per kilogram than 316L but usually less per metre of installed pipe, because its 450 MPa yield strength against 170 MPa allows a thinner wall and lighter supports. It…
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2026-08-31 · 8 min read
Welding titanium: shielding, contamination and why colour matters
Titanium absorbs oxygen, nitrogen and hydrogen rapidly above roughly 400 C, and the resulting layer is brittle. A weld is therefore judged by colour: bright silver is acceptable, straw is…
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2026-08-30 · 7 min read
Inconel 690 for steam generator tubing and caustic service
Inconel 690 contains 27 to 31 % chromium against the 14 to 17 % of Inconel 600, and that change is the reason it became the standard steam generator tube alloy. High chromium raises…
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2026-08-29 · 7 min read
Long radius versus short radius elbows: what the difference costs you
A long radius elbow has a centre to end dimension of 1.5 times the nominal pipe size; a short radius elbow has 1.0 times. The difference is not cosmetic. Short radius elbows have higher…
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2026-08-28 · 7 min read
Incoloy 925 for sour oil and gas flanges and tubular components
Incoloy 925 is an age hardenable iron nickel chromium alloy with molybdenum, copper and titanium, developed for oil and gas components that need the corrosion resistance of Incoloy 825 plus…
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2026-08-28 · 8 min read
Erosion corrosion in elbows and tees: where velocity attacks first
Erosion corrosion removes the protective film mechanically, so the metal corrodes and is swept away repeatedly. It concentrates where flow changes direction or impinges on a surface, which…
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2026-08-27 · 7 min read
Concentric versus eccentric reducers: choosing by what settles out
A concentric reducer keeps the centreline straight; an eccentric reducer offsets one side so the top or bottom stays level. Use concentric reducers on vertical lines and on horizontal lines…
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2026-08-26 · 7 min read
Inconel X-750: the alloy behind high temperature fasteners and springs
Inconel X-750 is a precipitation hardenable nickel chromium alloy used where a fastener or spring must hold load at temperatures that would relax stainless steel. It is hardened by a…
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2026-08-25 · 9 min read
NACE MR0175 / ISO 15156 requirements for flanges in sour service
Sour service compliance is not a property of the alloy name. It is a combination of the correct UNS number, the correct heat treatment condition, a verified hardness limit and documented…
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2026-08-24 · 7 min read
Incoloy A-286: high strength bolting for elevated temperature joints
Incoloy A-286 is an age hardenable iron nickel chromium alloy used for high strength bolting where stainless studs creep and nickel alloy studs are not justified. It holds useful strength…
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2026-08-24 · 8 min read
Galvanic corrosion when nickel alloys meet carbon steel
Joining a nickel alloy to carbon steel creates a galvanic cell in which the steel corrodes. The severity is controlled mainly by the area ratio: a small steel area coupled to a large nickel…
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2026-08-23 · 8 min read
Hydrostatic testing and non destructive examination of alloy fittings
Hydrostatic testing proves that a component holds pressure without leaking; it does not find most material defects. Non destructive examination finds the defects: ultrasonic testing for…
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2026-08-22 · 9 min read
Machining and welding Inconel 625 flanges: shop practice that works
Inconel 625 machines and welds well if you accept two rules: never let the tool rub, and never let the weld pool lose shielding. Most shop problems with 625 come from work hardening caused…
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2026-08-21 · 8 min read
Pipe schedules and wall thickness: choosing the wall that the duty needs
A schedule number is a shorthand for a wall thickness series, not a measure of strength. For the same nominal size, wall thickness increases with schedule number, but the actual thickness…
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2026-08-20 · 7 min read
Hastelloy C-22 vs C-276: choosing between the two workhorse C alloys
Both alloys solve aggressive chemical duty, but they are balanced differently. C-22 has higher chromium and lower tungsten, giving better resistance to oxidising media and improved thermal…
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2026-08-20 · 7 min read
Pickling, passivation and iron contamination control
Free iron embedded in the surface of stainless or nickel alloy components rusts, breaks the passive film and initiates pitting. Pickling removes the iron and the underlying depleted layer…
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2026-08-19 · 8 min read
PREN and critical pitting temperature: use both, trust neither blindly
PREN is a fast screening calculation, not a design method. It ranks alloys by chromium, molybdenum and nitrogen content but ignores nickel, microstructure and the real environment. Critical…
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2026-08-18 · 8 min read
Inconel 625 vs Hastelloy C-276: a selection method, not a preference
Choose Inconel 625 when the dominant risk is chloride pitting, crevice corrosion or sour service, and choose Hastelloy C-276 when the stream contains reducing acids or mixed acids at…
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2026-08-18 · 9 min read
Material selection for sour service: an H2S decision path
Sour service selection starts with the environment, not the alloy. Establish the hydrogen sulphide partial pressure, pH, chloride content, temperature and whether elemental sulphur is…
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2026-08-17 · 7 min read
Post weld heat treatment of nickel alloys: when to specify and when to avoid
Most nickel alloy weldments are placed in service without post weld heat treatment, and that is usually correct. Solid solution alloys such as Inconel 625 gain nothing from stress relief…
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2026-08-16 · 7 min read
Hastelloy B-2 and B-3: the hydrochloric acid specialists
Hydrochloric acid defeats chromium bearing alloys because chloride breaks down the passive film. The nickel molybdenum alloys answer this with about 28 % molybdenum and almost no chromium.…
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2026-08-15 · 8 min read
Inconel 718 vs Inconel 625 for flanges, fittings and bolting
Pick Inconel 718 when the joint is strength limited and Pick Inconel 625 when it is corrosion limited. 718 reaches roughly 1030 MPa yield after ageing against 414 MPa for annealed 625, but…
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2026-08-15 · 8 min read
Flange leak troubleshooting: a checklist that finds the real cause
Most leaking alloy flanges are not material failures. They are bolting problems, gasket problems, alignment problems or assembly problems. Work through the joint in order: confirm the…
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2026-08-14 · 8 min read
ASME B16.47 large diameter flanges: series A versus series B
Above NPS 24, flanges are covered by ASME B16.47 in two non interchangeable series. Series A derives from MSS SP-44 and is generally thicker and heavier with fewer, larger bolts. Series B…
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2026-08-13 · 7 min read
Solution annealing and sensitisation: what the heat treatment actually achieves
Solution annealing dissolves carbides and other second phase particles into the matrix and a rapid quench freezes that structure in place, giving uniform corrosion resistance. Sensitisation…
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2026-08-12 · 9 min read
How to choose a flange material for corrosive service
Choose flange material in five steps: define the actual fluid chemistry rather than the nominal one, identify which failure mode governs the joint, shortlist alloys using pitting resistance…
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2026-08-12 · 8 min read
Sigma phase in super duplex: how it forms and how to prevent it
Sigma phase is an iron chromium molybdenum intermetallic that precipitates in duplex and super duplex stainless steel between roughly 600 and 900 C. A few percent by volume is enough to…
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2026-08-11 · 7 min read
ASTM A182 duplex flange grades: F51, F53 and F55 decoded
ASTM A182 assigns F numbers to forged stainless grades. F51 is duplex 2205, F53 is super duplex 2507 and F55 is super duplex with added tungsten and copper. They are not interchangeable:…
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2026-08-10 · 8 min read
Inconel 625 weld overlay: the economical way to buy corrosion resistance
Weld overlay puts a 3 to 6 mm layer of Inconel 625 on a carbon steel flange so the wetted surface behaves like solid alloy while the load bearing section stays cheap and strong. It is the…
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2026-08-09 · 7 min read
Storage and handling of alloy flanges: protecting the investment
Most pre installation damage to alloy components is caused by handling, not by manufacture. Protect the sealing face, keep the material separated from carbon steel, avoid chloride exposure,…
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2026-08-08 · 7 min read
316L, 316Ti and 317L: choosing within the molybdenum stainless family
316L is the general purpose molybdenum stainless grade, 316Ti adds titanium stabilisation for service in the sensitising range, and 317L raises molybdenum and chromium for better pitting…
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2026-08-06 · 7 min read
Monel K-500: age hardened strength with Monel corrosion resistance
Monel K-500 adds about 2.7 to 3.5 % aluminium and 0.35 to 0.85 % titanium to the Monel 400 base, so it can be age hardened to roughly three times the yield strength of Monel 400 while…
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2026-08-04 · 8 min read
Titanium Grade 5 (Ti-6Al-4V) vs Grade 2: strength versus corrosion
Grade 5, Ti-6Al-4V, is the high strength titanium alloy with roughly double the yield strength of commercially pure Grade 2. Grade 2 is the corrosion and formability reference. Specify…
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2026-08-02 · 7 min read
Nickel 200 vs Nickel 201: the caustic service decision
Nickel 200 and Nickel 201 are commercially pure wrought nickel differing mainly in carbon: 0.15 % maximum for 200 and 0.02 % maximum for 201. That difference decides the temperature limit.…
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2026-07-30 · 7 min read
904L stainless steel for sulphuric acid piping
904L is a high alloy austenitic stainless steel with about 20 % chromium, 25 % nickel, 4.5 % molybdenum and 1.5 % copper. The copper addition is what gives it useful resistance to sulphuric…
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2026-07-28 · 8 min read
Inconel 625 vs 316L for marine piping: when the upgrade pays
Inconel 625 costs several times more per kilogram than 316L, so the decision is never about alloy price alone. Use 316L for low temperature, flowing, well aerated sea water with regular…
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2026-07-26 · 7 min read
254SMO vs 904L: two different answers to chloride problems
Both are super austenitic stainless steels, but they are optimised differently: 254SMO carries 6 % molybdenum and nitrogen for a PREN above 43 and outstanding chloride resistance, while…
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2026-07-22 · 7 min read
Stabilised stainless steel: when 321 and 347 beat 304H and 316H
321 is stabilised with titanium and 347 with niobium. Both bind carbon so chromium carbides cannot form at grain boundaries, which keeps welded components resistant to intergranular attack…
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2026-07-18 · 7 min read
17-4PH and 15-5PH: precipitation hardening stainless for strength
17-4PH and 15-5PH are martensitic precipitation hardening stainless steels hardened by a single low temperature age. Condition H900 gives the highest strength with lower toughness, while…
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2026-07-14 · 7 min read
310S and 253MA: austenitic grades for elevated temperature service
310S is the high chromium, high nickel austenitic grade for oxidation resistance to about 1150 C in air, while 253MA adds nitrogen, rare earth elements and a carefully balanced composition…
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2026-07-10 · 7 min read
How to read nickel alloy fitting markings (ASTM B366, ASME B16.9, MSS SP-25)
A compliant nickel alloy fitting carries five pieces of information: manufacturer symbol, material grade or UNS number, wall thickness or schedule, nominal size and heat number, together…
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2026-07-10 · 7 min read
Titanium Grade 7 and Grade 12: closing the crevice and reducing acid gaps
Grade 7 adds about 0.15 % palladium and Grade 12 adds about 0.8 % nickel and 0.3 % molybdenum to commercially pure titanium. Both raise resistance to crevice corrosion and to reducing acid…
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2026-06-25 · 7 min read
ASME B16.9 elbow dimensions explained: LR, SR, angles and tolerances
Every ASME B16.9 elbow dimension derives from one number: the radius. A long radius elbow has a centreline radius of 1.5 times nominal pipe size, so its 90° centre-to-end dimension equals…
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2026-06-05 · 7 min read
Duplex 2205 vs super duplex 2507: choosing the right duplex grade
Super duplex 2507 costs roughly 30 to 50 % more than 2205 but delivers about 30 % higher yield strength and a PREN above 40 against roughly 35. Choose 2507 when chloride concentration,…
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2026-05-20 · 8 min read
Inconel 718 heat treatment explained: solution anneal and double ageing
Inconel 718 develops its 1275 MPa tensile strength from gamma double prime Ni3Nb precipitates formed during a two-step ageing cycle. The standard aerospace route is solution anneal at…
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Nickel alloy flanges and pipe fittings: technical knowledge

Technical knowledge: nickel alloy flanges and pipe fittings

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