Fluorinea nd related compounds (e.g., chlorine trifluoride) are absorbed
into the PTFE resinw ith such intimate contact that the mixture becomes
sensitive to as ource of ignition, suchasi mpact.
The handling of 80% sodiumh ydroxide, aluminum chloride, ammonia,
and certain amines at high temperature may produce the same effect as
elemental sodium. Also,slow oxidative attack can be produced by 70% nitric
acid under pressure at 4888 F( 2508 C).
Refer to Table 4.18 for the compatibility of PTFE with selected corrodents
and Reference [1] for additional listings.
4.10.16 Tefzel
Tefzel (ETFE) is at rademark of DuPont. ETFE is am odified,p artially
fluorinated copolymero fe thylene andp olytetrafluoroethylene (PTFE).
Because it contains more than 75% by weight PTFE it has better resistance
to abrasion and cut-through than PTFE, while retaining most of the corrosionresistant properties.
The typical Tefzelc oating thickness is nominally 0.040 in. thick on all
interior surfaces and flange faces. Coating thickness from 0.020 to 0.090 in.
are available, dependingonapplication requirements and part geometry.For
coatings or linings appliedoncarbon steel or stainless steel, the continuous
service temperature rangeisfrom K 258 F(K 328 C) to 2258 F(1078 C).
Tefzel is inert to strong minerala cids, inorganic bases, halogens,a nd
strong metal salt solutions. Even carboxylic acids, aromatic and aliphatic
hydrocarbons, alcohols, ketones, aldehydes, ethers, chlorocarbons, and
classic polymer solventsh ave little effect on Tefzel. Ve ry strong oxidizing
acidsnear their boiling points, suchasnitric acid at high concentrations, will
effect ETFE to varying degrees as wills trong organic bases sucha sa mines
and sulfonic acids. Refer to Table 4.19 for the compatibility of ETFE with
selected corrodents and Reference [1] for additional listings.
4.10.17 Halar
Halar (ECTFE) is manufactured underthe trade name of Halar by Ausimont.
Ethylene–chlorotrifluoroethylene is a1 :1 alternating copolymero fe thylene
and chlorotrifluoroethylene. Thisc hemical structure gives the polymera
unique combination of properties. It possesses excellent chemical resistance
and, of allt he fluoropolymers, ECTFEr anks amongt he best for
abrasion resistance.
The resistance to permeation by oxygen, carbon dioxide, chlorine gas, or
hydrochloric acid is superior to that of PTFE or FEP,b eing1 0–100 times
better.W ater absorption is less than 0.1%.
Halar exhibits outstanding chemical resistance. It is virtually unaffected
by all corrosive chemicals commonly encountered in industry,i ncluding
strong mineral and oxidizing acids, alkalies, metal etchants, liquid oxygen,
ande ssentially allo rganic solvents except hota mines( e.g.,a niline
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into the PTFE resinw ith such intimate contact that the mixture becomes
sensitive to as ource of ignition, suchasi mpact.
The handling of 80% sodiumh ydroxide, aluminum chloride, ammonia,
and certain amines at high temperature may produce the same effect as
elemental sodium. Also,slow oxidative attack can be produced by 70% nitric
acid under pressure at 4888 F( 2508 C).
Refer to Table 4.18 for the compatibility of PTFE with selected corrodents
and Reference [1] for additional listings.
4.10.16 Tefzel
Tefzel (ETFE) is at rademark of DuPont. ETFE is am odified,p artially
fluorinated copolymero fe thylene andp olytetrafluoroethylene (PTFE).
Because it contains more than 75% by weight PTFE it has better resistance
to abrasion and cut-through than PTFE, while retaining most of the corrosionresistant properties.
The typical Tefzelc oating thickness is nominally 0.040 in. thick on all
interior surfaces and flange faces. Coating thickness from 0.020 to 0.090 in.
are available, dependingonapplication requirements and part geometry.For
coatings or linings appliedoncarbon steel or stainless steel, the continuous
service temperature rangeisfrom K 258 F(K 328 C) to 2258 F(1078 C).
Tefzel is inert to strong minerala cids, inorganic bases, halogens,a nd
strong metal salt solutions. Even carboxylic acids, aromatic and aliphatic
hydrocarbons, alcohols, ketones, aldehydes, ethers, chlorocarbons, and
classic polymer solventsh ave little effect on Tefzel. Ve ry strong oxidizing
acidsnear their boiling points, suchasnitric acid at high concentrations, will
effect ETFE to varying degrees as wills trong organic bases sucha sa mines
and sulfonic acids. Refer to Table 4.19 for the compatibility of ETFE with
selected corrodents and Reference [1] for additional listings.
4.10.17 Halar
Halar (ECTFE) is manufactured underthe trade name of Halar by Ausimont.
Ethylene–chlorotrifluoroethylene is a1 :1 alternating copolymero fe thylene
and chlorotrifluoroethylene. Thisc hemical structure gives the polymera
unique combination of properties. It possesses excellent chemical resistance
and, of allt he fluoropolymers, ECTFEr anks amongt he best for
abrasion resistance.
The resistance to permeation by oxygen, carbon dioxide, chlorine gas, or
hydrochloric acid is superior to that of PTFE or FEP,b eing1 0–100 times
better.W ater absorption is less than 0.1%.
Halar exhibits outstanding chemical resistance. It is virtually unaffected
by all corrosive chemicals commonly encountered in industry,i ncluding
strong mineral and oxidizing acids, alkalies, metal etchants, liquid oxygen,
ande ssentially allo rganic solvents except hota mines( e.g.,a niline
Corrosion of Linings and Coatings
134
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