monel alloy Archives

4. Application of Monel alloy:
The A and E levels of M35-1, M35-2 and QQ-N2-88 are usually used to manufacture refined Monel alloy pumps,

buttefly valve stem shaft parts (6)

valves and accessories. The B-grade (3.5%Si) Monel alloy with the highest Si content is mainly used to manufacture shafts and wear-resistant rings that require good wear resistance due to its high strength, corrosion resistance and wear resistance. Class D (4.0% Si) Monel alloy is used to manufacture parts that require higher wear resistance and corrosion resistance.
Monel alloy valves have two types: integral and internal. The integral Monel alloy valve means that the valve shell and internal parts are all Monel, which is mainly used in the HF acid regeneration tower part of the alkylation unit of the refinery. Due to the high HF acid regeneration temperature (149°C) and high water content, an overall alloy valve is required. In addition, the overall Monel alloy valve is also used in the production of ashless additives for catalysts in refineries and high-concentration chlor-alkali systems in chlor-alkali plants. Situation.
The Monel alloy internal valve means that the valve housing is made of carbon steel or stainless steel, and the internal valve is made of Moenl alloy. The Monel alloy valve with carbon steel as the shell is mainly used in the low temperature area of the HF calculation system of the alkylation unit of the refinery. The use of carbon steel is good for low temperature (≤71°C) anhydrous hydrofluoric acid (HF) However, carbon steel will form a film on its surface due to corrosion when used in this working condition for a long time. If carbon steel is used in the valve sealing part, the film formed after corrosion will affect the sealing performance of the valve. It should be pointed out that the commonly used Cr13 type sealing material for carbon steel valves cannot resist the corrosion of HF acid, and the internal material is much cheaper for Monel alloy valves. The Monel alloy valve with carbon steel as the shell can also be used in working conditions such as sea water. The valve housing is made of stainless steel Monel alloy internal valve, which is used in ethylene, propylene, liquid oxygen, pure oxygen, sea water and other working conditions. The monolithic Monel alloy valve and Monel alloy internal valve used in the alkylation unit require a pressure level of CL300 from a safety point of view. The pressure level of Monel alloy internal valve for other working conditions is CL150 and CL300. Or PN116-614Mpa etc.
5. Melting and casting of monel alloy:
The smelting and casting technology of Monel alloy is the key to determine whether the qualified Monel alloy castings can be produced. Because Moenl alloy has developed dendrites, shrinkage cavities and porosity, the tendency of gas absorption (hydrogen absorption, oxygen absorption) is great, and it will Sulfurizing chemical reaction occurs with molding materials. From a safety point of view, Monel alloy valves are required to undergo radiographic inspection in accordance with Class A pipeline valves in highly toxic and dangerous media such as hydrofluoric acid, chlorine and hydrogen chloride gas. . Although the American standard points out that casting M35-1 can be welded, in fact its weldability is extremely poor, and the quality of repaired castings is difficult to guarantee. The density of M35-1 alloy is 8163t/m3 (at 20°C), the solidification shrinkage rate is 21mm/m, and the alloy melting point is 1315-1345°C. The Class A and Class E of M35-1, M35-2 and QQ-N2-88 are delivered as cast. Although there are many grades of cast Monel alloy, when used to cast Monel alloy valve castings, M35-1 in ASTMA494 is mainly used.
Cast Monel alloy and deformed Monel alloy have little change in chemical composition (Table 4), but this change satisfies its better deformability for deformation and gold, while it provides better casting for cast alloys. performance. This is the reason why cast Monel alloy grades are used when casting, and deformed Monel alloy grades are used when selecting rolling materials.
Table 4. Commonly used cast and deformed Monel alloy chemical composition of valves (%)

Grade name	chemical composition /%
Grade name	C	Mn	Si	P	S	Cu	Fe	Ni	others
M35-1	≤0.35	≤1.5	≤1.25	≤0.03	≤0.03	26-33	≤3.5	Ba
Monel400	≤0.30	≤2.0	≤0.5		≤0.024	Ba	≤2.5	63-70
MonelK500	≤0.25	≤1.5	≤0.5		≤0.01	Ba	≤2.0	63-70	Al2.5-3.5, Ti0.35-0.85

6. Conclusion
The current U.S. technical standards for Monel alloys include ASTM, SAE, AMS (American Aeronautical Standards Institute), MIL (U.S. Department of Defense Standards), ANSI, ASME and QQ (American Federal Standards). For the Monel alloy of the same grade, different technical specification systems are adopted, not only the representation method of the grade is different, but the number and content of the specification are not completely the same. Usually military products use MIL, QQ or AMS specifications, and civil products use ASTM and ASME specifications.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D.

Monel alloy for corrosion resistant valve
1. Introduction/overview of Monel alloy:
Monel alloy, cast nickel alloy, Hastelloy alloy, etc. are all materials for making special purpose valves. Monel alloy is a Ni-Cu alloy in nickel-based corrosion-resistant alloys. It was first developed by the US Nickel Company. Its typical composition is 70% Ni and 30% Cu. It is the most widely used nickel-based corrosion-resistant alloy.

Monel alloy not only has high strength and toughness, but also has excellent resistance to corrosion by reducing acid and strong alkali media and sea water, so it is usually used to manufacture and transport hydrofluoric acid (HF), salt water, neutral media, and alkali salts. And reducing acid medium equipment. Monel alloy is also suitable for dry chlorine, hydrogen chloride, high temperature chlorine (425°C) and high temperature hydrogen chloride and other media, but it is not resistant to corrosion by sulfur-containing media and oxidizing media (such as nitric acid, media with high oxygen content), and it is nickel It reacts violently with sulfur and oxygen and easily forms Ni3S2 and NiO.

2. Performance of Monel alloy:
Monel alloy is a Ni-Cu solid solution, where Cu is used as a non-oxidizing resist added to Ni, which improves the corrosion resistance of nickel alloys and acts as a strengthening alloy. The addition of C can improve the casting performance of the alloy, but only 0.15% of C can be dissolved in the alloy at room temperature, and the excess C will be precipitated as a graphite phase. Adding 1.5%-3.5% Fe can also improve the casting performance of the alloy. Adding Mn and Si can improve the mechanical properties of the alloy, especially the content of Si has an important influence on the mechanical and physical properties of the Monel alloy.

3. Classification of Monel alloy:
Monel alloys are classified into casting alloys and deformed alloys.
3.1 Deformation alloy: There are more than 10 types of deformed Monel alloys in the United States, such as Monel400, MonelC, Monel403, Monel404, Monel R2405, Monel406, Monel411, MonelK500, MonelK501 and Monel502. Because Monel has its own representation methods in different American standard systems, SAE and ASTM jointly developed ASTM2SAE unified digital system (unified numbt system2 UNS) in order to facilitate the use and unified management of calculations. In the United States’ UNS, nickel alloys have 5 grades of deformed Monel alloys, including solid solution hardened No5500 (Monel400), No4404 (Monel404) and No4405 (MonelR2405), and precipitation hardened NO5500 (MonelK500) and NO5502 (Monel502). ) Etc. (refer to Table 1). Among them, the deformed Monel alloy commonly used in the manufacture of corrosion-resistant valves is Monel400 and MonelK500.
Table 1. Chemical composition of deformed Monel alloy in United States UNS

Grade name	chemical composition/ %
Grade name	C	Si	Mn	S	Ni	Fe	others
NO4400(Monel400)	≤0.3	≤0.5	2	≤0.024	63-70	≤2.5	Cu base
No4404(Monel404)	≤0.15	≤0.1	≤0.1	≤0.024	52-57	≤0.5	Cu base, Al≤0.05
No4405(MonelR2405)	≤0.3	≤0.5	≤2.0	0.025-0.06	63-70	≤2.5	Cu base
No5500(MonelK500)	≤0.25	≤0.5	≤1.5	≤0.01	63-70	≤2	Cu base, Al213-3115,Ti0135-0185
NO5502(Monel502)	≤0.10	≤0.5	≤1.5	≤0.01	63-70	≤2	Cu base, Al215-315

3.2 Casting alloy: The American cast Monel alloy has five grades of M35-1, M35-2, M-30H, M-25S and M-30C in ASTM A494 (Table 2), which is in the US Federal Standard QQ-N2-88 There are also 5 cast Monel alloys (Table 3).
Table 2. Cast Monel alloy in ASTM A494:

grade name

chemical composition /%

mechanical properties

P.S

Compressive strength/Mpa

Tensile strength/Mpa

Elongation rate/%

M35-1(a)

≤0.35

≤1.5

≤1.25

≤0.03

26-33

≤3.5

≥450

≥170

≥25

M35-2

≤0.35

≤1.5

≤2.00

≤0.03

26-33

≤3.5

≥450

≥205

≥25

M-30H

≤0.30

≤1.5

2.7-3.7

≤0.03

27-33

≤3.5

≥690

≥415

≥10

M-25S

≤0.25

≤1.5

3.5-4.5

≤0.03

27-33

≤3.5

243-294(b)

M-30C(a)

≤0.30

≤1.5

1.0-2.0

≤0.03

26-33

≤3.5

1-3

≥450

≥225

≥25

125-130(b)

Notes:
1.Ba=balance, means the balance is all Ni content.
2. To remove the weldability, it should be M3521 or M230C
3. This table is a data parameter
4. HB minimum is 300
Table 3 QQ2N2288 cast Monel alloy:

QQ-N-288	chemical composition /%							mechanical properties
QQ-N-288	C	Si	Mn	Cu	Fe	Ni	Nb	Compressive strength/Mpa	Tensile strength/Mpa	Elongation rate/%	HB
A	≤0.35	≤2.0	≤1.5	26-33	≤2.5	62-68		≥448	≥224	≥25	125-150
B	≤0.30	2.7-3.7	≤1.5	27-33	≤2.5	61-68		≥689	≥455	≥10	240-290
C	≤0.20	3.3-4.5	≤1.5	27-31	≤2.5	≥60		≥825	≥550	≥10	250-300
D	≤0.25	3.5-4.5	≤1.5	27-31	≤2.5	≥60					≥300
E	≤0.30	1.0-2.0	≤1.5	26-33	≤2.5	≥60	1-3	≥448	≥221	≥25	125-150

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Valve material and valve standards-(8)- Monel alloy application

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