Corrosion Control during Acid Cleaning of Heat Exchangers

Until the 1950s it was generally sufficient to clean new boilers or heat exchangers before commissioning by boiling out with alkali to remove traces of oil and grease and by subsequent flushing to remove debris. However, with the great increase in heat transfer ratings in recent years, it is shown that deposits a few thousandths of an inch in thickness can cause high internal tube temperatures which in turn can lead to corrosion of the tube metal. It is therefore obvious that the feed water quality must be very high and that it must be treated to maintain correct conditions in the heat exchanger. It is also essential to ensure that the plant enters service in a meticulously clean condition with the minimum layer of magnetite on the heating surfaces to ensure freedom from attack. The method which would be adopted at the present time to acid clean a new boiler is summarized together with precautions which should be taken. In addition, the necessity for laboratory trials before acid cleaning heat exchangers containing exotic materials is emphasized.

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Corrosion Control of Type 316L Stainless Steel in Sulfamic Acid Cleaning Solutions

CORROSION ◽

10.5006/1.3319152 ◽

2009 ◽

Vol 65 (7) ◽

pp. 491-500 ◽

Cited By ~ 4

Author(s):

J. R. Kish ◽

N. J. Stead ◽

D. L. Singbeil

Keyword(s):

Stainless Steel ◽

316L Stainless Steel ◽

Sulfamic Acid ◽

Corrosion Control ◽

Acid Cleaning ◽

Type 316L ◽

Type 316L Stainless Steel

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Corrosion inhibitors for acid cleaning of desalination heat exchangers: Progress, challenges and future perspectives

Journal of Molecular Liquids ◽

10.1016/j.molliq.2019.111760 ◽

2019 ◽

Vol 296 ◽

pp. 111760 ◽

Cited By ~ 4

Author(s):

I.B. Obot ◽

Abdelkader Meroufel ◽

Ikenna B. Onyeachu ◽

Abdulrahmane Alenazi ◽

Ahmad A. Sorour

Keyword(s):

Heat Exchangers ◽

Corrosion Inhibitors ◽

Future Perspectives ◽

Acid Cleaning

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Comparison of Acrylamide and Agar Gels by Freeze-Etching

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080456 ◽

1977 ◽

Vol 35 ◽

pp. 606-607

Author(s):

Russell L. Steere ◽

Eric F. Erbe

Keyword(s):

Electron Microscope ◽

Sodium Hydroxide ◽

Sodium Hypochlorite ◽

Chromic Acid ◽

Distilled Water ◽

Thin Sheets ◽

Acid Cleaning ◽

Agar Gels ◽

Freeze Etching ◽

Water Cut

Thin sheets of acrylamide and agar gels of different concentrations were prepared and washed in distilled water, cut into pieces of appropriate size to fit into complementary freeze-etch specimen holders (1) and rapidly frozen. Freeze-etching was accomplished in a modified Denton DFE-2 freeze-etch unit on a DV-503 vacuum evaporator.* All samples were etched for 10 min. at -98°C then re-cooled to -150°C for deposition of Pt-C shadow- and C replica-films. Acrylamide gels were dissolved in Chlorox (5.251 sodium hypochlorite) containing 101 sodium hydroxide, whereas agar gels dissolved rapidly in the commonly used chromic acid cleaning solutions. Replicas were picked up on grids with thin Foimvar support films and stereo electron micrographs were obtained with a JEM-100 B electron microscope equipped with a 60° goniometer stage.Characteristic differences between gels of different concentrations (Figs. 1 and 2) were sufficiently pronounced to convince us that the structures observed are real and not the result of freezing artifacts.

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High Resolution Stereography of Complementary Freeze-Fracture Replicas Reveals the Presence of Depressions Opposite Membrane Associated Particles of Split Membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066267 ◽

1971 ◽

Vol 29 ◽

pp. 442-443

Author(s):

Russell L. Steere

Keyword(s):

High Resolution ◽

Cardiac Muscle ◽

Electron Micrographs ◽

Chromic Acid ◽

Freeze Fracture ◽

Distilled Water ◽

Fine Scale ◽

Acid Cleaning ◽

Cleaning Solution

Complementary replicas have revealed the fact that the two common faces observed in electron micrographs of freeze-fracture and freeze-etch specimens are complementary to each other and are thus the new faces of a split membrane rather than the original inner and outer surfaces (1, 2 and personal observations). The big question raised by published electron micrographs is why do we not see depressions in the complementary face opposite membrane-associated particles? Reports have appeared indicating that some depressions do appear but complementarity on such a fine scale has yet to be shown.Dog cardiac muscle was perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (material furnished by Dr. Joaquim Sommer, Duke Univ., and VA Hospital, Durham, N.C.). Small strips were freeze-fractured in a Denton Vacuum DFE-2 Freeze-Etch Unit with complementary replica tooling. Replicas were cleaned in chromic acid cleaning solution, then washed in 4 changes of distilled water and mounted on opposite sides of the center wire of a Formvar-coated grid.

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Determination of creep mechanisms in various silicon carbides via TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143973 ◽

1986 ◽

Vol 44 ◽

pp. 484-487

Author(s):

C. H. Carter ◽

J. E. Lane ◽

J. Bentley ◽

R. F. Davis

Keyword(s):

Heat Exchangers ◽

Sintered Material ◽

Polycrystalline Material ◽

Chemical Vapor ◽

Graphite Substrate ◽

Second Phase ◽

Reaction Bonding ◽

Creep Mechanisms ◽

Porous Sic

Silicon carbide (SiC) is the generic name for a material which is produced and fabricated by a number of processing routes. One of the three SiC materials investigated at NCSU is Norton Company's NC-430, which is produced by reaction-bonding of Si vapor with a porous SiC host which also contains free C. The Si combines with the free C to form additional SiC and a second phase of free Si. Chemical vapor deposition (CVD) of CH3SiCI3 onto a graphite substrate was employed to produce the second SiC investigated. This process yielded a theoretically dense polycrystalline material with highly oriented grains. The third SiC was a pressureless sintered material (SOHIO Hexoloy) which contains B and excess C as sintering additives. These materials are candidates for applications such as components for gas turbine, adiabatic diesel and sterling engines, recouperators and heat exchangers.

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