6.4.8 Operation
Linedv essels should be properly identifiedw heni nstalled with the
allowable operating characteristicso ft he liner posted to avoid damage to
the liner during clean-up or repair operations.Most failures from this cause
result while vessels are being cleaned or repaired. If live steam is used to clean
the vessel,allowable operating temperatures may be exceeded. If the vessel is
solvent-cleaned, then chemical attackmay occur.
6.5E lastomeric Linings
Elastomers, sometimes referred to as rubbers, have given manyy ears of
service in providing protection to steel vessels. Each of these materials can
be compounded to improve certain,o fi ts properties. Because of this, it is
necessary that ac ompletes pecification for al iningu singt hese materials
include specificproperties that are required for the application. These include
resilience, hysteresis, static or dynamic sheera nd compression modulus,
flex fatigue and cracking, creep resistance to oils and chemicals, permeability,
and brittle point, all in the temperature ranget ob ee ncountered in service.
This will permit ac ompetent manufacturer to propose the proper lining
material forthe application.
Elastomeric liningsa re sheet-applied and bondedt ot he steel substrate.
Choice of bonding material to be used is dependendo nt he specific
elastomer to be installed. Repair of these linings is relatively simple. Many
older vessels with numerous repair patches are still satisfactorily operating.
The most common elastomers used for liningapplications along with their
operating temperature range are shown in Table 6.2.
Elastomeric materials can fail as the result of chemical actiona nd/or
mechanical damage.Chemical deterioration occurs as the resultofachemical
reaction between an elastomer and the medium or by the absorption of the
medium into the elastomer.Thisattackresults in the swellingofthe elastomer
and areduction in its tensile strength.
The degree of deterioration is af unction 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 quantitieso ft he material
they areincontactwith, especially organic liquids.This can result in swelling,
cracking, and penetration to the substrate of an elastomeric lined vessel.
Swelling can cause softening of the elastomer,and in alined vessel,introduce
high stressesa nd failure of the bond. If an elastomeric lining has high
absorption, permeationw ill probably result. Some elastomers, sucha st he
fluorocarbons, are easily permeatedb ut have very little absorption. An
approximation of the expectedpermeation and/or absorption of an elastomer
can be based on the absorption of water.This data is usually available.
Sheet Linings
295
CAT8247—CHAPTER 6—6/10/2006—12:28—SRIDHAR—XML MODEL B–pp. 287–402
Linedv essels should be properly identifiedw heni nstalled with the
allowable operating characteristicso ft he liner posted to avoid damage to
the liner during clean-up or repair operations.Most failures from this cause
result while vessels are being cleaned or repaired. If live steam is used to clean
the vessel,allowable operating temperatures may be exceeded. If the vessel is
solvent-cleaned, then chemical attackmay occur.
6.5E lastomeric Linings
Elastomers, sometimes referred to as rubbers, have given manyy ears of
service in providing protection to steel vessels. Each of these materials can
be compounded to improve certain,o fi ts properties. Because of this, it is
necessary that ac ompletes pecification for al iningu singt hese materials
include specificproperties that are required for the application. These include
resilience, hysteresis, static or dynamic sheera nd compression modulus,
flex fatigue and cracking, creep resistance to oils and chemicals, permeability,
and brittle point, all in the temperature ranget ob ee ncountered in service.
This will permit ac ompetent manufacturer to propose the proper lining
material forthe application.
Elastomeric liningsa re sheet-applied and bondedt ot he steel substrate.
Choice of bonding material to be used is dependendo nt he specific
elastomer to be installed. Repair of these linings is relatively simple. Many
older vessels with numerous repair patches are still satisfactorily operating.
The most common elastomers used for liningapplications along with their
operating temperature range are shown in Table 6.2.
Elastomeric materials can fail as the result of chemical actiona nd/or
mechanical damage.Chemical deterioration occurs as the resultofachemical
reaction between an elastomer and the medium or by the absorption of the
medium into the elastomer.Thisattackresults in the swellingofthe elastomer
and areduction in its tensile strength.
The degree of deterioration is af unction 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 quantitieso ft he material
they areincontactwith, especially organic liquids.This can result in swelling,
cracking, and penetration to the substrate of an elastomeric lined vessel.
Swelling can cause softening of the elastomer,and in alined vessel,introduce
high stressesa nd failure of the bond. If an elastomeric lining has high
absorption, permeationw ill probably result. Some elastomers, sucha st he
fluorocarbons, are easily permeatedb ut have very little absorption. An
approximation of the expectedpermeation and/or absorption of an elastomer
can be based on the absorption of water.This data is usually available.
Sheet Linings
295
CAT8247—CHAPTER 6—6/10/2006—12:28—SRIDHAR—XML MODEL B–pp. 287–402