Page 53 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

PIPING

PIPING 2.3

TABLE 2.1 Galvanic Series of Metals and Alloys

Corroded end (anodic, or least noble)
Magnesium alloys
Zinc
Beryllium
Aluminum alloys
Cadmium
Mild steel, wrought iron
Cast iron, flake or ductile
Low-alloy high-strength steel
Nickel-resist, types 1 & 2
Naval bronze (CA464), yellow bronze (CA268), aluminum bronze (CA687), red bronze
(CA230), admiralty bronze (CA443), manganese bronze
Tin
Copper (CA102, 110), silicon bronze (CA655)
Lead-tin solder
Tin bronze (G & M)
Stainless steel, 12–14% chromium (AISI Types 410, 416)
Nickel silver (CA732, 735, 745, 752, 764, 770, 794)
90/10 Copper-nickel (CA706)
80/20 Copper-nickel (CA710)
Stainless steel, 16–18% chromium (AISI Type 430)
Lead
70/30 Copper-nickel (CA715)
Nickel-aluminum bronze
Inconel alloy 600
Silver braze alloys
Nickel 200
Silver
Stainless steel, 18 chromium, 8 nickel (AISI Types 302, 304, 321, 347)
Monel alloys 400, K-500
Stainless steel, 18 chromium, 12 nickel-molybdenum (AISI Types 316, 317)
Carpenter 20 stainless steel, Incoloy alloy 825
Titanium, Hastelloy alloys C & C276, Inconel alloy 625
Graphite, graphitized cast iron
Protected end (cathodic, or most noble)

Erosion Corrosion. This is caused by a wearing away of the pipe wall, usually as a result
of excessive fluid velocity or impingement by suspended solids.

Localized Corrosion
This takes place on small areas of the surface, usually at high rates, and takes various forms:

Stress-Corrosion Cracking. This type of corrosion is the physical deterioration and
cracking of the pipe wall caused by a combination of high operating temperature, tensile
stress on the pipe, and chemicals in the fluid stream.

Pitting. This is characterized by deep penetration of the metal at small areas of the sur-
face, concentrating in small cells, without affecting the entire surface.
Crevice Attack Corrosion. This occurs at junctions between surfaces (often called crud
traps) where a crack exists that allows an accumulation of a corroding agent.

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