Anti-corrosion High Temperature Centrifugal Fan

Overview

Temperature capability and corrosion resistance frequently conflict: 310S resists scaling well but is attacked by chlorides, while 316L resists corrosion but loses strength as temperature rises. The approach is to fix the material route from the medium first and then support it with lining and process measures.

Material Trade-offs

First establish whether the medium is oxidising or contains chlorides or sulphur, then trade off temperature capability against corrosion resistance.

Location	Combination	Basis
Impeller	316L, 310S or nickel alloy	Grade confirmed from medium and temperature
Casing lining	Ceramic fibre with corrosion resistant barrier	Addresses insulation and corrosion together
Shaft	Heat resistant alloy with thermal sleeve	Controls the shaft temperature gradient
Shaft seal	High temperature graphite or PTFE combination	Combines temperature capability and sealing
Fasteners	Heat resistant stainless steel	Prevents oxidation seizure

Construction and Operating Measures

Location	Combination	Basis
Dew point control	Operation above the acid dew point	Avoids condensation driven corrosion
Heat-up curve	Controlled heating with moisture removal	Protects lining and welds
Expansion joints	Divided according to thermal growth	Releases thermal stress
Lining anchoring	Anchors fix the insulation layer	Prevents detachment blocking the flow path
Temperature survey	Thermocouples with periodic measurement	Finds local hot spots early

Applications

Applications include sulphur bearing flue gas heat recovery, chloride bearing hot gas, hazardous waste incineration tail gas and metallurgical and chemical hot gas.

At the same temperature, oxidising and chloride bearing media can lead to opposite material conclusions, so temperature alone is not a sufficient basis for selection.

Start-up and shutdown are when the lining and welds are most likely to crack, so heating and cooling rates should be written into the operating procedure.

Acceptance and Verification

Standard	Title	Purpose
HG/T 20679	Design code for external anti-corrosion of chemical equipment and piping	Anti-corrosion design for chemical media
GB/T 4237	Hot rolled stainless steel plate, sheet and strip	Stainless impeller and casing material
GB/T 20878	Stainless and heat-resisting steels - Designation and chemical composition	High temperature and corrosion resistant grades
GB/T 3003	Refractory fibres and products	High temperature lining material and acceptance
GB/T 1236	Industrial fans - Performance testing using standardized airways	Air flow, pressure and efficiency testing

Please provide medium composition, medium temperature and dew point, dust load and air flow. Size and motor power are calculated for the actual duty.

FAQ

How do I balance temperature capability against corrosion resistance?

First determine the corrosion type from the medium: oxidising high temperature service tends towards high nickel chromium stainless steel such as 310S, while chloride bearing or reducing service requires avoiding high nickel grades and considering nickel alloys or a non-metallic lining. The answer follows the medium rather than the temperature alone.

When should 310S be avoided?

Its weakness is chloride resistance. In chloride bearing gas or dust it is prone to pitting and stress corrosion, so a more chloride resistant material or an isolating layer is required.

How is dew point corrosion prevented?

Three measures together: keep the operating temperature above the acid dew point, avoid condensation during shutdowns, and select materials for wet conditions rather than dry conditions. Missing any one of the three shortens service life.

Related pages: Non-standard fan range  high temperature fan range  Anti-corrosion fan range