Operational guidelines and code of practice for stainless steel
Operational guidelines and code of practice for stainless steel
Operational guidelines and code of practice for stainless steel
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OGCP - Stainless Steel Products – DWI Ref 56.4.477 – APPENDIX<br />
use in the chemical <strong>and</strong> process plant industries.<br />
The ferritic <strong>stainless</strong> <strong>steel</strong>s are used in the more mildly corrosive environments, being <strong>of</strong>ten used in trim<br />
work <strong>and</strong> somewhat less dem<strong>and</strong>ing applications.<br />
The corrosion resistance <strong>of</strong> martensitic <strong>stainless</strong> <strong>steel</strong>s is similar to that <strong>of</strong> the ferritic types, whilst that<br />
<strong>of</strong> the precipitation hardening <strong>stainless</strong> <strong>steel</strong>s is claimed to be similar to the 304 (1.4301) austenitic type<br />
<strong>stainless</strong> <strong>steel</strong>.<br />
Duplex <strong>stainless</strong> <strong>steel</strong>s are alloys designed to have improved localised corrosion resistance, specifically<br />
to stress corrosion cracking, crevice <strong>and</strong> pitting corrosion.<br />
Corrosion attacks at the surface <strong>of</strong> a material. It is important there<strong>for</strong>e to ensure that the surface finish is<br />
suitable <strong>and</strong> that the surface is clean <strong>and</strong> uncontaminated (particularly from non-<strong>stainless</strong> <strong>steel</strong> contact).<br />
This enables the "inherent" corrosion resistance conferred by the additions <strong>of</strong> chromium, nickel,<br />
molybdenum etc. to be fully exploited.<br />
Benefits <strong>of</strong> <strong>stainless</strong> <strong>steel</strong>s<br />
In economic terms <strong>stainless</strong> <strong>steel</strong>s can compete with higher cost engineering metals <strong>and</strong> alloys based on<br />
nickel or titanium, whilst <strong>of</strong>fering a range <strong>of</strong> corrosion resisting properties suitable <strong>for</strong> a wide range <strong>of</strong><br />
applications. They have better strength than polymer products such as GRP. Stainless <strong>steel</strong>s can be<br />
manipulated <strong>and</strong> fabricated using a wide range <strong>of</strong> commonly available engineering techniques <strong>and</strong> are<br />
fully "recyclable" at the end <strong>of</strong> their useful life.<br />
In addition to their corrosion resistance, <strong>stainless</strong> <strong>steel</strong>s also <strong>of</strong>fer other useful properties, depending on<br />
their "family".<br />
The austenitics, in the fully annealed heat-treated condition, are:<br />
• Tough, with no brittle transition, down to cryogenic temperatures.<br />
• Para-magnetic with relative magnetic permeabilities around 1.05.<br />
The martensitic <strong>and</strong> precipitation hardening families are hardenable by heat treatment.<br />
The duplex <strong>stainless</strong> <strong>steel</strong>s are stronger than the austenitics in the annealed condition <strong>and</strong> so can be used<br />
in thinner sections to save weight <strong>and</strong> cost.<br />
The ferritics are lower cost <strong>stainless</strong> <strong>steel</strong>s.<br />
SCI©2002 33<br />
January 2002: Issue 1
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