Brass specifications

Attack on metals can be a function of fuel components as well as of water and oxygen. Organic acids react with cadmium plating and 2inc coatings. Traces of H2S and free sulfur react with silver used in older piston pumps and with copper used in bearings and brass fittings. Specification limits by copper and silver strip corrosion tests are requited for fuels to forestall these reactions. 

Steel, copper, and brass fiber may have a variety of aspect ratios, shape, ie, straight versus curved fibers and cross-sectional geometry, surface roughness, and chemical compositions. Fibers having tight specifications in terms of cleanliness, chemical composition, and aspect ratio ate necessary. The fibers are usually machined from larger metallic forms. 

Metal or metal oxides may be added to perform specific functions. Brass chips and copper powder are frequently used in heavy-duty organics where these metaUics act as scavengers to break up undesirable surface films. Zinc chips used in Class A organics contribute significantly to recovery of normal performance following fade. Aluminum is also used. Most of these inorganic materials tend to detract from antinoise properties and mating surface compatibihty. 

Corrosion also occurs as a result of the conjoint action of physical processes and chemical or electrochemical reactions (1 3). The specific manifestation of corrosion is deterrnined by the physical processes involved. Environmentally induced cracking (EIC) is the failure of a metal in a corrosive environment and under a mechanical stress. The observed cracking and subsequent failure would not occur from either the mechanical stress or the corrosive environment alone. Specific chemical agents cause particular metals to undergo EIC, and mechanical failure occurs below the normal strength (5aeld stress) of the metal. Examples are the failure of brasses in ammonia environments and stainless steels in chloride or caustic environments. 

Virtuallv evety alloy system has its specific environment conditions which will prodiice stress-corrosion cracking, and the time of exposure required to produce failure will vary from minutes to years. Typical examples include cracking of cold-formed brass in ammonia environments, cracking of austenitic stainless steels in the presence of chlorides, cracking of Monel in hydrofluosihcic acid, and caustic embrittlement cracking of steel in caustic solutions. 

Certain conditions, ultimately dictated by economics, make the substitution of more resistant materials a wise choice. Stainless steels (not sensitized) of any grade or composition do not form tubercles in oxygenated water neither do brasses, cupronickels, titanium, or aluminum. However, each of these alloys may suffer other problems that would preclude their use in a specific environment. 

Sampie Specifications 1 in. (2.5 cm) outer diameter, admiralty brass tubes... 

A specific corrodent. One of the unusual and interesting features of SCC is the specificity of the corrodent. A particular alloy system is susceptible to SCC only when exposed to certain corrodents, some or all of which may be unique to that particular alloy system. For example, austenitic stainless steels (300 series) are susceptible to cracking in chloride solutions but are unaffected by ammonia. Brasses, on the other hand, will crack in ammonia but remain unaffected by chlorides. The corrodent need not be present at high concentrations. Cracking has occurred at corrodent levels measured in parts per million (ppm). 

Sample Specifications 1 in. (25 mm) outer diameter, 30 ft (9 m) long, inhibited admiralty brass... 

Sample Specifications h in. (13 mm) outside diameter, admiralty brass... 

In any specific environment, only certain alloys are affected. Substitution of more resistant materials does not always necessitate major alloy compositional changes. Adding as little as a few hundredths of a percent of arsenic, for example, can markedly reduce dezincification in cartridge brass. Antimony and phosphorus additions up to 0.1% are similarly efficacious. 

Sampie Specifications % in. (1.9 cm) outer diameter, CDA 442 uninhibited brass tubing... 

When possible, avoid coupling materials having widely dissimilar galvanic potentials. If this cannot he avoided, make use of favorable area ratios by giving the active metal a large exposed area relative to the noble metal. For example, copper or copper-based alloy tubes may be joined to a steel tube sheet. Because of the favorable area ratio in this case, a relatively inexpensive steel tube sheet may be intentionally substituted for a bronze or a brass tube sheet if thickness specifications allow for a small amount of galvanic corrosion of the steel. 

Sampie Specifications 15 in. (38.1 cm) diameter aluminum ring the ring has a rectangular cross section measuring 1 x 2 in. (214 x 5 cm) the ring is fitted with a series of brass inlet and outlet nozzles... 

Gelb-guss, m. yellow brass, -harz, n. yellow resin yellow rosin, -heit, /. yellowness, -holz, n. fustic, specif, old fustic 3 dlowwood. 

Where an under-slung condenser has been specified, the provision of a basement to the engine room offers the attraction of compactness at the expense of enhanced civil works, while alternatively, the specification of pannier condensers can obviate the need for a basement and will simplify the foundation design, but will considerably increase the floor area requirements. The condensing plant itself consists essentially of banks of tubes through which cooling water flows and around which exhausted steam from the turbine is condensed to form a vacuum. Such tubes have traditionally been made of brass, but where severe corrosion conditions exist, cupro-nickel is sometimes used. 

Many of the alloys of copper are more resistant to corrosion than is copper itself, owing to the incorporation either of relatively corrosion-resistant metals such as nickel or tin, or of metals such as aluminium or beryllium that would be expected to assist in the formation of protective oxide films. Several of the copper alloys are liable to undergo a selective type of corrosion in certain circumstances, the most notable example being the dezincification of brasses. Some alloys again are liable to suffer stress corrosion by the combined effects of internal or applied stresses and the corrosive effects of certain specific environments. The most widely known example of this is the season cracking of brasses. In general brasses are the least corrosion-resistant of the commonly used copper-base alloys. 

Only certain specific environments appear to produce stress corrosion of copper alloys, notably ammonia or ammonium compounds or related compounds such as amines. Mercury or solutions of mercury salts (which cause deposition of mercury) or other molten metals will also cause cracking, but the mechanism is undoubtedly differentCracks produced by mercury are always intercrystalline, but ammonia may produce cracks that are transcrystalline or intercrystalline, or a mixture of both, according to circumstances. As an illustration of this, Edmundsfound that mercury would not produce cracking in a stressed single crystal of brass, but ammonia did. 

Table III presents integral excess entropies of formation for some solid and liquid solutions obtained by means of equilibrium techniques. Except for the alloys marked by a letter b, the excess entropy can be taken as a measure of the effect of the change of the vibrational spectrum in the formation of the solution. The entropy change associated with the electrons, although a real effect as shown by Rayne s54 measurements of the electronic specific heat of a-brasses, is too small to be of importance in these numbers. Attention is directed to the very appreciable magnitude of the vibrational entropy contribution in many of these alloys, and to the fact that whether the alloy is solid or liquid is not of primary importance. It is difficult to relate even the sign of the excess entropy to the properties of the individual constituents.

Electronic specific heat of a brasses, 131 Electrostatic interaction, 391 Energy, of binding, 34 matrix, 271... 

---