Category Archives for Materials

Stacks Material

Stack design and materials selection are based on strength, oxidation resistance, and acid attack from condensing acids in the flue gas. Most stacks are built of carbon steel. They may have an internal refractory lining when flue gas temperatures are … Continue reading

18. May 2018 by sam
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Tube Supports Material

Maximum tube support temperatures for various materials are summarized in Table 8 of API-560. Intermediate tube supports exposed to radiant heat and full firebox temperature are usually made of HH or HK alloy, the cast versions of 25-12 and 25-20 … Continue reading

18. May 2018 by sam
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Outlet Headers Material

Hydrogen and ammonia plant reforming furnaces operate at outlet temperatures in excess of 1500°F. Outlet headers are usually built of Incoloy 800H, since this is one of the few alloys with sufficient strength and ductility for the service. Outlet headers … Continue reading

18. May 2018 by sam
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Holding Members and Screws Material

To avoid failures, be sure they conform to Specification HTR-MS-203. Failure of holding members and screws has historically been a serious problem in header-type furnaces. If not strong enough, they bend or distort under the severe mechanical loads needed to … Continue reading

18. May 2018 by sam
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Seal Weld Dissimilar Metal Joints Material

Where a transition from one tube material to another must be made in a header-type furnace, the connecting header may be the same as either of the two tube materials. But when a transition is made from ferritic (carbon steel … Continue reading

18. May 2018 by sam
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Return Bends and Headers Material

Return bends are typically made of the same material as tubes. They should be wrought, not cast, due to the poorer mechanical properties and greater likelihood of defects in castings. Avoid longitudinal welds in return bends. In fired heaters using … Continue reading

18. May 2018 by sam
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Metallurgical Problems

A variety of metallurgical considerations influence selection of tube materials. Those described below can be controlled by proper selection of tube material. They may be difficult or impossible to control when the wrong tube material has been used. Graphitization. This … Continue reading

18. May 2018 by sam
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Fin Materials

Oxidation, Corrosion, and Temperature Considerations. On extended surface (finned or studded) tubes, the fin or stud material is chosen largely on the basis of oxidation resistance. Because fin temperature will often approach flue gas temperature, higher alloys are usually required … Continue reading

18. May 2018 by sam
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Tubes Materials – Internal Corrosion

Corrosion Allowance. Besides choosing a corrosion-resistant tube material, you need for it to be thick enough to compensate for the degree of corrosion you expect. Usual practice is to design tubes to last at least 10 years. Typical corrosion allowances … Continue reading

18. May 2018 by sam
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Tubes Materials

The major factors to consider when selecting tube materials are cost, strength, internal corrosion, and external oxidation. Temperature limits imposed by strength and external oxidation tend to be about the same for any given tube material, but the temperature limits … Continue reading

18. May 2018 by sam
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