Corrosion Resistant Seamless Pipe Special Alloys For Petrochemical Industry G-3 / UNS N06985

Corrosion resistant alloy seamless pipe Alloy G-3, UNS N06985 for oil-gas

1 PRODUCT

Corrosion resistant alloy seamless pipe Alloy G-3, UNS N06985 for oil-gas handling sulphuric and phosphoric acids at ambient and high temperature.

2 EQUIVALENT DESIGNATION

W. Nr. 2.4619, NiCr22Mo7Cu(DIN), NiCr22Fe20Mo7Cu2(ISO), Hastelloy® G-3, Inconel® Alloy G-3, VDM^® Alloy G-3, Nicrofer ® 4823 hMo

3 OVERVIEW

Alloy G-3 is a stabilized austenitic nickel-chromium-iron alloy with additions of molybdenum and copper. Some of the minor elements are controlled to yield increased resistance to heat- affected-zone (HAZ) corrosion and improved weldability. Alloy G-3 has excellent corrosion resistance to oxidizing chemicals and atmospheres. It is also resistant to reducing chemicals because of its nickel and copper contents. Nickel also provides the alloy with exceptional stress-corrosion-cracking resistance in chloride-containing environments. The high molybdenum provides very good resistance to pitting and crevice corrosion. The low carbon helps prevent sensitization, giving the alloy resistance to inter-granular corrosion.

Alloy G-3 is characterized by:

■ Very good resistance to a wide range of corrosive media under both oxidising and reducing conditions

■ Excellent resistance to crevice and pitting corrosion and to stress corrosion cracking

4 APPLICATION

Alloy G-3 is particularly suitable for handling reducing acids such as phosphoric and sulfuric. It is used in flue gas desulfurization systems (scrubbers), especially in quencher, damper, and outlet ducting areas. It can be used in other air pollution control systems in the chemical and pulp and paper industries. It is a good candidate for evaporators, heat- exchangers, tank liners, and other equipment in phosphoric acid manufacturing plants.

Alloy G-3 finds wide application in the chemical and petrochemical industry for components handling sulphuric and phosphoric acids at ambient and higher temperatures.

Typical applications are:

■ Vessels and equipment for the dissolution of waste nuclear fuel elements

■ Components for flue gas desulphurization systems

■ Equipment and components in sour gas service

■ Equipment for acetic acid manufacture

5 CHEMICAL COMPOSITION

6 PHYSICAL PROPERTIES

Density: 0.3 lb/in³ (8.3g/cm³)

Melting range: 1260-1343°C (2300-2450°F)

7 MECHANICAL PROPERTIES

Alloy G-3 displays good mechanical properties.

The following properties are applicable to Alloy G-3 in the solution treated condition and indicated size ranges.

Table 3 Minimum mechanical properties at room temperature.

8 CORROSION RESISTANCE

Alloy G-3 is highly resistant to corrosion in acids and alkalis under both oxidising and reducing conditions.

It exhibits very good resistance to mixed inorganic and organic acids, fluosilicic acid, contaminated nitric, sulphuric and phosphoric acid, hydrofluoric acid and flue gases below dew point.

The high molybdenum content ensures excellent resistance to crevice and pitting corrosion.

Alloy G-3 is virtually immune to chloride-induced stress corrosion cracking.

9 WORKING INSTRUCTION

Alloy G-3 is readily fabricated by usual industrial procedures. Hot and cold working, however, require high- power machines, owing to the high strength of the material. Forming operations are performed by standard procedures for nickel alloys.

Heating

It is very important that the workpiece be clean and free from any contaminant before and during heating.

Alloy G-3 may become embrittled if heated in the presence of contaminants such as sulphur, phosphorus, lead and other low-melting-point metals. Sources of contamination include marking and temperature-indicating paints and crayons, lubricating grease and fluids, and fuels.

Hot working

Alloy G-3 may be hot-worked in the range 1150 to 900°C (2100 to 1650°F). Cooling should be by water quenching or as fast as possible.

Solution treatment is required after hot working to ensure maximum corrosion resistance and optimum properties.

Cold working

Cold working should be carried out on solution-treated material. Alloy G-3 has a much higher work-hardening rate than austenitic stainless steel and the forming equipment must be adapted accordingly. When heavy cold working is performed, inter-stage annealing may become necessary. After cold reductions of more than 15%, final annealing is required before use.

Machinability

Alloy G-3 should be machined in the solution treated condition. The alloy’s high work-hardening rate should be considered; i.e. only low surface cutting speeds are possible compared with low-alloy standard austenitic stainless steels. Tools should be engaged at all times. Heavy feeds are important in getting below the workhardened skin.

10 HEAT TREATMENT

Annealing

Solution treatment should be carried out in the temperature range 1100 to 1150°C (2010 to 2100°F).

Water quenching after heating is essential for maximum corrosion resistance.

During any heating operation, the precautions outlined earlier regarding cleanliness must be observed.

Hardening

Alloy G-3 can be hardened by cold working.

11 TUBING SIZES

OD: 3-1/2 inch (88.9mm), 4 inch (101.6mm), 4-1/2 inch (114.3mm)

WT: 5.49mm - 16.00mm

Length: R1 (6.10 - 7.32m), R2 (8.53 - 9.75m), R3 (11.58 - 12.80m)

12 CASING SIZES

OD: 4-1/2 inch (114.3mm), 5 inch (127.0mm), 5-1/2 inch (139.7mm), 6-5/8 inch (168.28mm), 7 inch (177.8mm), 7-5/8 inch (193.68mm), 7-3/4 inch (196.85mm), 8-5/8 inch (219.08mm)

WT: 5.21mm - 22.22mm

Length: R1 (4.88 - 7.62m), R2 (7.62 - 10.36m), R3 (10.36 - 14.63m)

13 DIMENSION TOLERANCE

The following tolerances apply to the outside diameter, D, of pipe

Wall thickness: tolerance for pipe –12.5 %

Inside diameter: inside diameter, d, is governed by the outside diameter and mass tolerances.

14 HOT EXTRUSION PROCESS

Bar → Inspection → Peeling → Cutting → Boring → Chamfering → Inspection → Cleaning → Preheating → Induction heating → Broaching → Induction heating → Hot extruding → Heat treatment → Straightening → Saw cutting → Pickling → Inspection & repairing → CR(CD) → Deoil → Heat treatment → Straightening → Cut to length → Pickling → NDT (Eddy-current inspection, UT, Hydraulic pressure inspection)→Packing

15 FEATURE OF EXTRUDED SEAMLESS TUBE

Extrusion pipe production is completely different from skew rolling and roller rolling and has following characteristics

(1) Compared with other methods of tube process, extrusion method is characteristic of the metal in the process of forming through three-way compressive stress, which can be used to produce low plasticity steel and alloy, such as zirconium alloy, titanium alloy, Ni-Cr-Fe heat resistant alloy, etc for application of atomic energy industry and special chemical industrial. And good surface quality could be obtained.

(2) Extrusion method has great flexibility and mobility due to the simple die, easy to manufacture and replace.

(3) The specification range of tube produced by extruder is larger than other process.

(4) Compared with other methods of tube process, extrusion can get better quality, the mechanical properties of tube are more even, and the inner and outer surface of the tube is better than that of rolling.

16 HOT PERFORATION PROCESS

Bar → Inspection → Peeling → Cutting → Centering → Heating → Perforation → Pickling → End cutting → Inspection and repairing → CR(CD) → Deoil → Heat treatment → Straightening → Cut to length → Pickling → UDT (Eddy current inspection, UT, Hydraulic pressure inspection) → Packing

17 COMPETITIVE ADVANTAGE

(1) More than 50 years experience of research and develop in high temperature alloy, corrosion resistance alloy, precision alloy, refractory alloy, rare metal and precious metal material and products.
(2) 6 state key laboratories and calibration center.
(3) Patented technologies.
(4) Excellent performance when running in oil-gas well several tens of thousands of meters deep.

(5) We have terminal customers like Baker Hughes, Halliburton, China national offshore oil corporation LTD (CNOOC), etc.

18 STANDARD SPECIFICATION

Alloy G-3 is approved as a material of construction for pressure vessels under Section VIII of the Boiler and Pressure Vessel Code of the American Society of Mechanical Engineers.

Alloy G-3 is stated in NACE standard MR0175

Rod and bar: ASTM B581, ASME SB581, DIN 17752, ISO 9723

Plate, sheet and strip: ASTM B582, ASME SB-582, DIN 17750, ISO 6208

Seamless pipe and tube: ASTM B622, ASME SB622, ASTM B829, ASME SB829, DIN 17751, ISO 6207

Chemical composition: DIN 17744, ISO 9722

Wire: ISO 9724

Forging: ISO 9725

19 BUSINESS TERM