Materials

B7 and B7M shall be heat treated by quenching in a liquid medium and tempering. For B7M fasteners, the final heat treatment, which may be the tempering operation if conducted at 1150 ¡ãF [620 ¡ãC] minimum, shall be done after all machining and forming operations, including thread rolling and any type of cutting.

ASTM A193 Grade B7 is a standard material specification for chromium-molybdenum alloy steel fasteners for use in high tensile, high temperature and special purpose applications.

Grade B7 is a heat-treated chromium-molybdenum alloy steel with minimum tensile requirement of 100 ksi, yield of 75 ksi and maximum hardness of 35 HRC.

The material is made up of carbon, manganese, phosphorus, sulfur, silicon, chromium and molybdenum in the composition.

The term “bolting material” as used in this specification covers, rolled, forged or strain hardened bars, bolts, washers, screws, studs and stud bolts.

ASTM A320 L7 washers are specially engineered for LOW temperature performance. These fasteners are commonly used for valves, flanges, fittings, and pressure vessels.

ASTM specifications recommend a minimum Charpy impact value for ASTM A320 L7 Stud Bolts to be 20-ft-lbf @ -150F. The Charpy impact test determines the total amount of energy that is absorbed by a material during fracture, thereby indicating the material¡¯s notch toughness.

The ASTM A320 Grade L7 specification covers stainless steel bolting materials for low temperature service. This standard cover rolled, forged, or strains hardened bars, bolts, screws, studs, and stud bolts used for pressure vessels, valves, flanges, and fittings.

It has high strength and excellent corrosion resistance in various acidic and alkaline environments, especially suitable for reducing conditions. It also has good ductility and thermal conductivity.

Alloy 400 is a solid solution alloy that can only be hardened by cold working.

The Monel 400 alloy is also known as super alloy monel. This alloy is available in some standard shapes such as hexagon, round, tube, pipe, plate, strip, sheet and wire.

ASTM A193 Grade B7 specification covers requirements for high tensile alloy steel bolting material for use in high temperature or high-pressure service and other special purpose applications.

It is a standard specification defining typical chemical composition, mechanical properties, hardness requirement, preferential heat treatment, product marking, certification and other requirements, suitable for bolting used in pressure vessel service, valves, flanges and fittings. ASTM A193 defines both SI (Metric) and inch-pound units.

Grade B7 is a heat-treated chromium-molybdenum low-alloy steel with minimum tensile strength requirement of 125 ksi (860 Mpa), yield 105 ksi (720 Mpa), and maximum hardness of 35HRC.

Although there are several variations of the Hastelloy nickel alloy, Hastelloy C-276 is by far the most widely used.

INCONEL alloy C-276 (UNS N10276/W.Nr. 2.4819) is known for its corrosion resistance in a wide range of aggressive media.

The high molybdenum content imparts resistance to localized corrosion such as pitting.

The low carbon minimizes carbide precipitation during welding to maintain resistance to intergranular attack in heat-affected zones of welded joints.

It is used in chemical processing, pollution control, pulp and paper production, industrial and municipal waste treatment and the recovery of ¡°sour¡± natural gas.

Applications in air pollution control include stack liners, ducts, dampers, scrubbers, stack-gas re-heaters, fans and fan housings.

In chemical processing, the alloy is used for components including heat exchangers, reaction vessels, evaporators and transfer piping.

INCONEL C-276 alloy has excellent resistance to a wide variety of chemical process environments, including strong oxidizers such as ferric and cupric chlorides, hot contaminated media (organic and inorganic), chlorine, formic and acetic acids, acetic anhydride, and seawater and brine solutions.

It is used in flue gas desulfurization systems because of its excellent resistance to sulfur compounds and chloride ions encounted in most scrubbers.

C-276 alloy has excellent resistance to pitting and to stress-corrosion cracking. It is also one of the few materials that withstands the corrosive effects of wet chlorine gas, hypochlorite, and chlorine dioxide.

INCONEL alloy C-276 is designated as UNS N10276 and Werkstoff Nr. 2.4819. It is listed in NACE MR0175 for oil and gas service.

Hastelloy C-276 also has exceptional resistance to pitting, stress-corrosion cracking and oxidizing atmospheres, as well as excellent resistance to multiple different chemical environments.

The high molybdenum content of Hastelloy?* C276 provides the alloy with its excellent resistance to pitting and crevice corrosion.

Hastelloy C-276 is a nickel-molybdenum-chromium alloy with excellent corrosion resistance in severe environments.

The high nickel and molybdenum contents make the nickel steel alloy especially resistant to pitting and crevice corrosion in reducing environments while chromium conveys resistance to oxidizing media.

Hastelloy X pipe bend is widely used for a variety of chemical processing parts, including retorts, pyrolysis tubing, and muffles due to its exceptional resistance to stress-corrosion cracking.