Brass fittings

Glass-lined reactor systems ate used occasionally for halogenated resins to prevent corrosion of the reactor components. Copper and brass fitting should be avoided due to the significant induence on resin cute characteristics. 

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. 

Turner, M. E.., Further Studies on the Influence of Water Composition on the Dezincihcation of Duplex Brass Fittings , Proc. Soc. Water Treat. Exam., 14, 81 (1965) C.A., 63, 15984e Frade, G. and Lacombe, P., Influence of Intergranular Diffusion in the Kinetics of Dezincihcation of 70/30 Brasses Without Additions at 450-900 C , Compt. Rend., 260, 5022 (1965) C.A., 63, 5323c... 

Dezincification of brasses This may occur, particularly in stagnant or slowly-moving warm or hot waters relatively high in chloride and containing little carbonate hardness. Dezincification of a brasses is inhibited by the usual arsenic addition (see Fig. 4.12), but two-phase brasses are liable to severe attack in some waters . In such waters the use of duplex-structure brass fittings should be avoided. 

GC instruments are designed so that columns can be replaced easily by disconnecting a pair of brass fittings inside the oven. This not only facilitates changing to a different stationary phase altogether, but... 

Copper can be present in fuel systems in the form of heating coils, cooling coils, brass fittings, or bronze parts. Copper is quite resistant to corrosion by water but can be attacked by ammonia and sulfur compounds. Finished fuels usually do not contain ammonia unless the ammonia somehow carries over from refining process operations. Sulfur compounds such as hydrogen sulfide and possibly elemental sulfur are more frequently the cause of copper corrosion problems in fuel systems. 

Cast-iron or brass fittings or valves in hydrocarbon service... 

Dezincification of brass fittings occurs when the /1-phase is present. Dezincification is accelerated by high temperature, high chloride concentration, low flow-rates and differential aeration. Dezincification can be inhibited by the addition of 1% tin and 0.04% arsenic. 

Acid Pumps.—When an acid or other corrosive substance is to be handled by a pump no material should be used that is attacked by the substance. For this reason pumps may be constructed either wholly of brass, bronze, rubber or even stone ware, or wholly of iron or they may be merely bronze fitted, which means that certain working parts such as pistons, rods, pump pistons, etc., are made of bronze or bronze lined. In ordering bronze or brass-fitted pumps it should be clearly specified what parts should be made of bronze or brass. In an all-iron pump the pump cylinder is bored to size and has no lining. The valve seats and stems are made of malleable iron. 

If the size permits it in a brass fitted pump the piston rod should be split in the cross head, and the steam piston rod should be made of steel. Brass at the high temperature in the steam cylinder is too soft to wear well. 

At some point in construction, draw the wires into the box through the brass ports, then seal these ports with epoxy or silicone. Flow the epoxy or silicone into the brass fittings around the wires so that no gaps allow air to enter or leave the system. This can be a bit tricky and may take several times to get it tightly sealed. 

As stated earlier, brass is a good material for the transport of hydrogen and oxygen within a system, but it is extremely susceptible to corrosion from potassium hydroxide. This incompatibility is a draw back, but plated brass fittings,... 

Fig. 7.5 Details of piston seals (a) a piston honed to a mirror finish that is accurately cylindrical and machined to an interference fit to the cylinder, (b) a A ring of bronze or brass, fitting the chamfer of the piston and precisely fitting the diameter of the cylinder (this ring will deform somewhat to create the high-pressure seal above pressures of about 5 kbar), (c) a rubber O-ring which can seal pressures below 5 kbar (above this pressure elastomers tend to become brittle), (d) a backing ring of PTFE, (e) a circlip to prevent rings falling off when the piston is extracted, (f) an accurately machined 45° chamfer.

Schock MR, Neff CH. 1988. Trace metal contamination from brass fittings. J Am Waterworks Assoc 80 47-56. 

Sit-and-soak tests have been earned out with BS 7766 standard test water and with laboratory tap waters (composition of waters given in Table 4.3). Pipe rig experiments have been carried out with laboratory tap waters, and four materials have been tested copper, brass (eopper with brass fittings for pipe rigs), galvanized steel, and stainless steel. 

The total inner surface of the brass fittings is 128 cm 10 % which represents about 6.5 % of the total inner... 

Figure 4.3 Design of test rigs, (a) Pipe materials (copper, galvanized steel, stainless steel) (b) copper pipe with brass fittings...

Cu from Copper rig — — Cu from copper with brass fittings rig... 

Figure 4.9 Comparison of copper concentrations after 8-hours stagnation in copper rig and copper with brass fittings rig experiments...

For CRECEP, values between 5 and 10 ig were observed, but lead was also detected in the blank at the same level. In that case, a small, variable contamination by lead comes from materials before the rigs (a few centimetres of galvanized steel, and brass devices) and carmot be imputed to contamination from brass fittings. 

Table 4.10 Zinc concentrations in copper with brass fittings rig experiments at different stages... 

Figure 4.10 Copper with brass fittings rig experiments. Zine eoneentrations as function of stagnation time and operating time...

Reproducibility within each laboratory can be assessed by comparing copper concentrations from copper rigs and from copper rigs with brass fittings. For all laboratories, copper concentration curves overlap almost perfectly after the initial period where migration of zinc from brass fitting influence (reduce) the migration of copper. 

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