194
Fundamentals of Corrosion
ing. Unfortunately, the lower the crystallinity, the greater the likelihood of
permeation.
Resistance to stress cracking can be reduced by the absorption of substances that chemically resemble the polymer and will plasticize it. In addition, the mechanical strength will also be reduced. Halogenated chemicals,
particularly those consisting of small molecules containing chlorine or fluorine, are especially likely to be similar to the fluoropolymers and should be
tested for their effect.
The presence of contaminents in a fluid may act as an accelerator. For
example, polypropylene can safely handle sulfuric or hydrochloric acids, but
iron or copper contamination in concentrated sulfuric or hydrochloric acids
can result in the stress cracking of polypropylene.
6.3 Elastomeric Linings
Elastomers, sometimes referred to as rubbers, have given many years of service in providing protection to steel vessels. Each of these materials can be
compounded to improve certain of its properties. Because of this, it is necessary that a complete specification for a lining using these materials includes
specific properties that are required for the application. These include resilience, hysteresis, static or dynamic shear and compression modulus, flex
fatigue and cracking, creep resistance to oils and chemicals, permeability,
and brittle point, all in the temperature range to be encountered in service.
This will permit a competent manufacturer to propose the proper lining
material for the application.
Elastomeric linings are sheet-applied and bonded to the steel substrate.
The choice of bonding material to be used depends on the specific elastomer
to be installed. Repair of these linings is relatively simple. Many older vessels with numerous repair patches are still operating. The same general rules
apply for the design, fabrication, and preparation of the steel shell for lining
that apply for other sheet linings.
The most common elastomers used for lining applications, along with their
operating temperature range, are given in Table 6.3.
Elastomeric materials can fail as the result of chemical action and/or
mechanical damage. Chemical deterioration occurs as the result of a chemical reaction between an elastomer and the medium or by the absorption of
the medium into the elastomer. This attack results in the swelling of the elastomer and a reduction in its tensile strength.
The degree of deterioration is a function of the temperature and the concentration of the corrodent. In general, the higher the temperature and the higher
the concentration of the corrodent, the greater will be the chemical attack.
Elastomers, unlike metals, absorb varying quantities of the material they are
Fundamentals of Corrosion
ing. Unfortunately, the lower the crystallinity, the greater the likelihood of
permeation.
Resistance to stress cracking can be reduced by the absorption of substances that chemically resemble the polymer and will plasticize it. In addition, the mechanical strength will also be reduced. Halogenated chemicals,
particularly those consisting of small molecules containing chlorine or fluorine, are especially likely to be similar to the fluoropolymers and should be
tested for their effect.
The presence of contaminents in a fluid may act as an accelerator. For
example, polypropylene can safely handle sulfuric or hydrochloric acids, but
iron or copper contamination in concentrated sulfuric or hydrochloric acids
can result in the stress cracking of polypropylene.
6.3 Elastomeric Linings
Elastomers, sometimes referred to as rubbers, have given many years of service in providing protection to steel vessels. Each of these materials can be
compounded to improve certain of its properties. Because of this, it is necessary that a complete specification for a lining using these materials includes
specific properties that are required for the application. These include resilience, hysteresis, static or dynamic shear and compression modulus, flex
fatigue and cracking, creep resistance to oils and chemicals, permeability,
and brittle point, all in the temperature range to be encountered in service.
This will permit a competent manufacturer to propose the proper lining
material for the application.
Elastomeric linings are sheet-applied and bonded to the steel substrate.
The choice of bonding material to be used depends on the specific elastomer
to be installed. Repair of these linings is relatively simple. Many older vessels with numerous repair patches are still operating. The same general rules
apply for the design, fabrication, and preparation of the steel shell for lining
that apply for other sheet linings.
The most common elastomers used for lining applications, along with their
operating temperature range, are given in Table 6.3.
Elastomeric materials can fail as the result of chemical action and/or
mechanical damage. Chemical deterioration occurs as the result of a chemical reaction between an elastomer and the medium or by the absorption of
the medium into the elastomer. This attack results in the swelling of the elastomer and a reduction in its tensile strength.
The degree of deterioration is a function of the temperature and the concentration of the corrodent. In general, the higher the temperature and the higher
the concentration of the corrodent, the greater will be the chemical attack.
Elastomers, unlike metals, absorb varying quantities of the material they are