BUNA "N"
Buna "N" is commonly referred to as a nitrile rubber, and is ASCO's standard synthetic elastomer for accomplishing resilient-type seating or sealing. It has excellent compatibility for most air, water and light oil applications. It has a useful temperature range of 0F. ( - 18°C.) to 180°E (82°C.).

NEOPRENE
Neoprene is principally used as an external seal in refrigeration applications. It is also utilized for oxygen service. It has a useful temperature range of 0°E ( - 18°C.) to 180°E (82°C. ).

ETHYLENE PROPYLENE
Ethylene propylene is selected for applications which are above the Buna "N" temperature range such as handling hot water and steam. Ethylene propylene has an extremely wide range of fluid compatibility but has the distinct disadvantage that it cannot be used with petroleum-based fluids or fluids so contaminated (such as lubricated air). It has a useful temperature range of—10°E ( - 23°C.) to 300°E ( 149°C. ).

Viton(R)*/FLUOREL,** ETC.
Viton(R) is a fluorocarbon elastomer which was primarily developed for handling hydrocarbons such as jet fuels, gasolines, solvent, etc., which normally caused detrimental swelling to Buna "N". Viton(R) has a high temperature range similar to ethylene propylene but has the advantage of being somewhat more resistant to "dry heat." Viton(R) has a rather wide range of chemical compatibility. It has a useful temperature range of 0°E ( - 18°C.) to 350°E (177°C.).

TEFLON
Teflon and teflon with fillers are considered more of a plastic than a resilient-type material. They are virtually unattached by any fluid. Their temperature usage has ranged from discs for cryogenic valves to discs for steam valves. They are not easily fabricated and are known to have "cold flow" characteristics which may contribute to objectionable leakage particularly on gases.


Material Selection Guide

Carbon Steel

Carbon Spring Temper Steel
SAE 1070-1090 high carbon blue tempered and polished spring steel is a standard material for both rings and springs. It is the lowest cost material and best suited for applications that have a protected environment, as carbon steel corrodes if not lubricated or atmospherically sealed. Additional corrosion protection can be added with a special finish. Products are supplied with an oil dip finish providing adequate protection for shipment and shelf storage. Carbon steel is highly magnetic and is typically blue in color.

Stainless Steels

302 Stainless Steel
302 is the standard stainless steel for retaining rings. This widely used material is specified because of its combination of corrosion resistance and physical properties. 302 obtains its spring temper condition by cold working. Though it is categorized as being a nonmagnetic stainless, 302 becomes slightly magnetic as a result of cold working. It is not hardenable by heat treatment. 302 has a silver-gray color.

316 Stainless Steel
316 is also a standard material for retaining rings. Nearly identical in physical properties and heat resistance to 302, 316 provides additional corrosion resistance, particularly against pitting, due to its molybdenum chemical content. 316 is generally used in food, chemical and sea water applications. 316 has lower magnetism than 302. This stainless grade is also not hardenable by heat treatment. 316 has a silver-gray color.

17-7 PH/C Stainless Steel
Similar in corrosion resistance to type 302, this alloy is a standard for wave springs. Spring properties are achieved by precipitation hardening. As a Result, the material may be subjected to a temperature of 650° F without a loss of spring properties. 17-7 PH C/CH-900 exhibits magnetism similar to high carbon steel. After precipitation hardening, 17-7 has a blue to brown color, although atmosphere controlled heat treatments provide a bright color.

Super Alloys

Inconel X-750
This nickel-chromium alloy is used most commonly in high temperature and corrosive environments. Two tempers exists, the most common Inconel X-750 is precipitation heat treated to a spring temper condition. In this state, it has temperature resistance to 700° F. The National Association of Corrosion Engineers (NACE) approves this hard temper to Specification MR-01-75 (Rc 50 maximum) for spiral retaining rings and wave / compression springs. #1 temper has a lower tensile strength but provides temperature protection to 1000° F. Both spring temper and #1 temper may be heat treated in either an open air or atmosphere controlled furnace. Open air heat treatment may produce oxidation which often results in a black ash residue. An atmosphere controlled environment eliminates oxidation and produces a component with no residue. Rings and springs manufactured from Inconel have a blue / silver-gray color and exhibit no magnetism.

A286 Alloy
In applications up to 1000° F, this alloy exhibits similar properties to Inconel X-750 spring temper. Its spring temper condition is obtained by precipitation hardening. This material exhibits no magnetism and has a blue / silver-gray color.

Elgiloy
Known for its excellent resistance to corrosive environments, elevated temperature resistance and high strength. Elgiloy exhibits no-magnetism and is blue / brown in color as a result of heat treatment.

Coppers

Beryllium Copper Alloy #25
This alloy produces excellent spring properties due to a combination of low modulus of elasticity and high ultimate tensile strength. The alloy gains its physical properties by precipitation hardening. Beryllium copper is non-magnetic. Its electrical conductivity is about 2-4 times as great as phosphor bronze.

Phosphor Bronze, Grade A
Phosphor bronze offers electrical conductivity and fair spring properties. It is purchased in spring temper condition to maximize spring characteristics. Phosphor bronze is hardenable only by cold working. This material is nonmagnetic.


TYPE 316 STAINLESS STEEL
Type 316 is a molybdenum-bearing grade. This addition gives the better overall corrosion resistance properties than type 304 and higher creep strength at elevated temperatures. Type 316 gives useful service at room temperature in sulphuric acid of concentration of lower than 15% and higher than 85%. It also resists chloride attack and is often selected for use in marine atmospheres.

Type 316L with its .03 maximum carbon content is used in applications where it is not possible to anneal after welding and where maximum corrosion resistance is required.

Corrosion Resistance: Good resistance to a wider range of chemicals than type 304. Highly resistant to the complex sulphur compounds used in pulp and paper processing. Also resists attack of marine and corrosive industrial atmospheres.

Heat Resistance: Good oxidation resistance in intermittent service to 1600°F and in continuous service to 1700°F. Continuous use of 316 in 800 – 1575°F range not recommended but often performs well in temperatures fluctuating above and below this range. Type 316L is more resistant to carbide precipitation and can be used in the above temperature range.

Heat Treatment: Annealing – heat to 1850 - 2050°F and cool rapidly. These grades cannot be hardened by thermal treatment.

Welding: Good characteristics suited to all standard methods. Use Type 316, 316L filler rods or electrodes depending on application. Welded sections in Type 316 require post-weld annealing for maximum corrosion resistance. This is not required if Type 316L is used.

TYPICAL APPLICATIONS: The list of applications for this general-purpose grade is very extensive and includes, Pulp & Paper Equipment Dairy & Brewery Heat Exchangers Fittings, Food Applications Pharmaceutical Equipment Photographic Developing Equipment, Exterior Architectural Components in marine coastal areas Dyeing equipment



 

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